Employment 3. Topographical Anatomy of Temporal Region. Topographical Anatomy of the Lateral Facial Region of the Head. Surgical Anatomy of the Parotid Gland, the Parapharyngeal Space. The Facial Nerve Branches, the Parotid Duct. Incisions in Case of Purulent Parotitis. Topographical Anatomy of Facial Deep Region. The Anatomical Basement and Technique of Block Anesthesia of Trigeminal Nerve Branches. Operations in Case of Chronic Frontitis and Maxillitis.

 

 

INTERIOR OF THE SKULL

SKULL CAP

The inner aspect of the skull has a top part or skull cap and a floor or base. The skull cap is concave and presents depressions for the convolutions of the cerebrum and many furrows for the branches of the meningeal vessels. Along the midline is a longitudinal groove, narrow in front at the frontal crest, where it begins, but broader behind. This lodges the superior sagittal sinus, and its margins afford attachments for the falx cerebri. Bordering the sagittal groove, granular pits are seen which increase with age and occasionally are of sufficient depth to pass through the diploe to the outer table. They lodge and are eroded by the arachnoid granulations. In addition there are numbers of minute nutrient foramina.

BASE OF THE SKULL AND THE CRANIAL FOSSAE

The base of the skull on its inner surface shows a natural subdivision into 3 cranial fossae: anterior, middle and posterior. Since the anterior fossa is on a higher plane than

 

FIG. The upper surface of the base of the skull. The anterior fossa is on a higher plane than the middle fossa, and the middle is higher than the posterior; in this way three terraces are formed.

 

the middle, and the middle is higher than the posterior, there is a natural tendency toward the formation of 3 terraces. The anterior cranial fossa is limited posteriorly by the posterior edges of the lesser wings of the sphenoid and in the median part by the anterior edge of the optic groove of the sphenoid. It lodges the frontal lobes of the brain and the olfactory bulbs and tracts. The floor of the fossa is depressed in its median part, where it constitutes the roof of the nasal cavity. The median part is formed by the cribriform plate of the ethmoid bone, through which the crista galli, or cock's comb, rises. It is an upward continuation of the nasal septum and gives attachment to the anterior end of the falx cerebri. The foramen caecum is a small pit found directly in front of the crista. In early life the superior longitudinal sinus communicates with the veins of the nose through this foramen, but in the adult it is usually closed, hence its name—caecum (blind). The cribriform plate is perforated like a sieve by numerous olfactory nerves, which are clothed in an arachnoid sheath and arise from the olfactory cells in the nasal mucosa. At the side of the cribriform plate the anterior and the posterior ethmoidal foramina are found. They mark the medial ends of two short canals that lead from the orbital cavity and open at the side of the cribriform plate; they transmit the anterior and the posterior ethmoidal arteries and the anterior ethmoidal nerve. The anterior ethmoidal artery and nerve, after passing through the foramina, run on the cribriform plate and then descend into the nose through the nasal slit which is found at the side of the front of the crista galli. Anterolateral to the median area, the roof of the frontal sinus and the roof of the orbit are found. Fractures of the anterior fossa may involve the cribriform plate and be accompanied by lacerations of the meninges and the mucous membrane of the roof of the nose. Such an injury gives rise to epistaxis, accompanied or followed by a discharge of cerebrospinal fluid. There may result some loss of smell due to laceration of the olfactory nervfcs as they pass upward from the nose and, if dural injury is present, it affords a route whereby infection can travel to the intracranial region from the nose. Meningitis or abscess in the frontal lobe may be a sequela of this type of fracture. If the cribriform plate does not heal after fracture and if a dural laceration remains unrepaired, there may be a continuous discharge of cerebrospinal fluid from the nose, known as cerebrospinal rhinorrhea. When the fracture involves the orbital plate of the frontal bone, subconjunctival hemorrhage is a characteristic feature, and the hemorrhage may seep within the orbit, producing an exophthalmos. The frontal sinus may also be involved. The middle cranial fossa is shaped like a butterfly, having a small median and two lateral expanded concave parts. The median part is formed by the upper surface of the body of the sphenoid. The sella turcica is the saddle-shaped area that accommodates the pituitary gland. Anteriorly is the ridge known as the tuberculum sellae, on either side of which is an anterior clinoid process. Immediately anterior to this process the optic foramen is situated at the end of the optic groove. The posterior part of the sella turcica is formed by the crest of the dorsum sellae, ending laterally in the posterior clinoid process The lateral part of the floor of the middle cranial fossa is formed by the greater wing of the sphenoid, the upper aspect of the petrous part of the temporal and a portion of the squamous part of the temporal bone. These lateral parts lodge the temporal lobes of the brain. The superior orbital fissure transmits to the orbital cavity the oculomotor, the trochlear, the ophthalmic division of the trigeminal and the abducens nerves, some filaments from the cavernous plexus of the sympathetic system and the orbital branch of the middle meningeal artery. From the orbital cavity this fissure also transmits the ophthalmic veins and a recurrent branch of the lacrimal artery to the dura mater.On either side of the sella is the carotid groove for the internal carotid artery. Three foramina run almost parallel with this groove. These are, from anterior to posterior and from medial to lateral: the foramen rotundum for the passage of the maxillary nerve, the foramen ovale for the mandibular nerve, the accessory meningeal artery and the lesser petrosal nerve, and the foramen spinosum for the passage of the middle meningeal vessels and a recurrent branch of the mandibular nerve. Medial to the foramen ovale is the foramen lacerum, a short, wide canal rather than a foramen, its lower part being filled by a layer of fibrocartilage. Its upper and inner parts transmit the internal carotid artery, which is surrounded by a plexus of sympathetic nerves. The petrous portion of the temporal bone forms a large and important part of the floor of the fossa. The highest part of this bone is known as the arcuate eminence and marks the position of the superior semicircular canal. Lateral to the eminence and immediately adjoining the squamous portion of the bone, the tegmen tympani is found. This is a very thin plate of bone which roofs the tympanic antrum, the tympanic cavity and the auditory tube. The important relationship of the thin tegmen tympani intervening between the inferior surface of the temporal lobe of the brain and the tympanic cavity cannot be overemphasized. This bone is the only barrier which exists between a diseased middle ear and the membranes of the brain or the brain itself. The hiatus for the greater superficial petrosal nerve is a small slit seen lower down on the anterior surface and about midway between the apex of the petrous temporal and the side of the skull. It communicates with the facial canal in the interior of the bone and transmits a slender nerve from which it takes its name. This nerve has its origin from the facial in the substance of the temporal bone and runs in a medial direction forward to the foramen lacerum. The trigeminal impression is found at the upper aspect of the apex of the petrous temporal and is represented by a slightly hollowed-out area. In it is lodged the trigeminal ganglion, which extends forward over the upper and the lateral parts of the foramen lacerum. The middle fossa is the commonest site of fracture of the skull because of its position and because it is weakened by numerous foramina and canals. Frequently, the tegmen tympani is fractured, and the tympanic membrane torn. Then blood and cerebrospinal fluid are discharged from the external auditory meatus and appear at the ear. The facial and the auditory nerves may be involved. At times the walls of the cavernous sinus are lacerated, and cranial nerves 3, 4 and 6, which lie in relation to its lateral wall, may also be injured. Fractures involving the middle cranial fossa may also pass through the sphenoid bone or the base of the occipital bone and cause bleeding into the mouth. The posterior cranial fossa is the largest and deepest of the cranial fossae and lodges the hind brain (cerebellum, pons and medulla oblongata). Its floor is formed by the basilar, the condylar and the squamous parts of the occipital bone; its lateral wall, by the posterior surface of the petrous and the medial surface of the mastoid part of the temporal bone. The foramen magnum is the most prominent feature of the fossa. At the anterolateral boundary of the foramen the anterior condylar canal is found which transmits the hypoglossal nerve. This nerve arises by several roots of origin, and the canal is frequently divided into two parts by a small bar of bone. The foramen magnum transmits a number of structures, the most important being the medulla oblongata, the meninges, the vertebral arteries and the ascending parts of the accessory nerves. This foramen marks the lowest part of the posterior cranial fossa.

The clivus is the broad, sloping surface that exists between the anterior margin of the foramen magnum and the root of the dorsum sellae; it is related to the pons and the medulla oblongata. The internal auditory meatus is found at the posterior aspect of the petrous temporal and runs laterally into the bone. Through it pass the motor and the sensory roots of the facial nerve, the auditory nerve, the internal auditory branch of the basilar artery and the auditory vein which joins the inferior petrosal sinus. The jugular foramen is situated between the lateral part of the occipital and the petrous part of the temporal bone. It is a large aperture with irregular margins and transmits three sets of structures. At times small spicules of bone project from its margin and may divide it partly or completely into corresponding compartments. The anteromedial compartment transmits the inferior petrosal sinus and a meningeal branch of the ascending pharyngeal artery. The middle compartment transmits the glossopharyngeal, the vagus and accessory nerves. The posterolateral compartment is larger than the other two and transmits the sigmoid sinus as it becomes the internal jugular vein, and a meningeal branch of the occipital artery. The inferior petrosal sinus, which passes through the anterior part of the foramen, becomes the internal jugular vein immediately outside of the skull. The transverse groove begins at the side of the internal occipital protuberance and sweeps around the cranial vault to the lateral end of the upper margin of the petrous temporal. It then joins the sigmoid groove, which curves downward and descends along the side wall of the skull and extends in a medial direction to end at the jugular foramen. The right transverse groove is wider than the left because it usually receives the sagittal sinus. The mastoid foramen is an aperture of variable size which leads from the exterior of the skull into the sigmoid groove on the side wall of the posterior cranial fossa. Through it a mastoid vein and the mastoid emissary vein and the mastoid branch of the occipital artery pass. The aqueduct of the vestibule (aqueductus vestibuli) is found about Vi inch lateral to the internal auditory meatus. Fractures of the posterior fossa are probably more important than such injuries in the other fossae, since it is here that a small fissure fracture may prove to be fatal. The bone is thin in places and, since there is no outlet for the escape of blood or cerebrospinal fluid as in the anterior and the middle fossae, these fractures may be overlooked. Some days after the injury, blood may be noted over the mastoid process. Fractures of the base of the skull involving the hypoglossal canal may be manifested by paralysis of one side of the tongue.

 

Facial region of the Head

EMBRYOLOGY At the anterior end of the embryo an opening called the stomodeum appears during the latter part of the first month of intra-uterine life. The face is formed from five processes surrounding this opening: one frontonasal, two maxillary and two mandibular processes. The mandibular processes grow medially, fuse and unite in the midline, forming the lower jaw or mandible. When a failure of fusion of these processes occurs, a fissure of the lower lip results. The fusion of the upper processes converts the single stomodeal orifice into the cheeks, the whole upper lip except the philtrum (the vertical groove in the middle of the upper lip), most of the upper jaw and the palate. The appearance of an olfactory pit divides the frontonasal process into a medial and two lateral nasal processes. The medial process forms the septum of the nose, the philtrum and premaxilla; the lateral processes form the side of the nose but take no part in the formation of the upper lip. By imperfect fusion various defects result, such as harelip, macrostoma, microstoma, cleft palate, etc.

SKIN, BLOOD AND NERVE SUPPLY

 Skin. The skin of the face is thin, vascular, movable and abundantly supplied with sebaceous and sweat glands. The absence of deep fascia in the anterior aspect of the face permits muscles arising from the bone to be inserted directly into the skin. The glands situated in the skin lie in immediate relationship to the subjacent loose areolar tissue, and it is the presence of this loose tissue, unsupported by deep fascia, that permits therapid spread of edema. Over the lower part of the nose, however, the skin is firmly bound to the underlying cartilage, and inflammations here are extremely painful. The skin over the chin resembles the integument of the scalp in that it is very dense and adherent to the parts beneath. Because of its mobility and vascularity, the skin of the face is especially adaptable to plastic operations and sound healing. The "dangerous area" of the face is triangular and bounded by lines that join the root of the nose with the angles of the mouth. The venous drainage from this area enters the angular vein, which communicates with the cavernous sinus via the superior ophthalmic vein. Therefore, boils or carbuncles in this region may produce a cavernous sinus thrombosis.

Blood Supply. The blood supply of the face is free, and anastomoses are numerous. The arterioles have a rich supply of sympathetic vasomotor nerves from the superior cervical ganglion, and because of this, blushing and blanching occur readily in emotional states. The main artery of the face is the facial (external maxillary), which is a branch of the external carotid. It appears at the base of the jaw immediately in front of the masseter muscle, passes upward in a tortuous manner toward the angle of the mouth and the side of the nose, and terminates near the inner canthus of the eye, where it anastomoses with the nasal branch of the ophthalmic artery. It crosses the lower jaw, the buccinator muscle, the upper jaw and the levator angulis oris; it is covered superficially by the platysma, the risorius, the zygomaticus major and minor and the levator labii superioris. In its lower part the artery rests directly on the mandible and is covered only by skin and the risorius muscle. Leaving the mandible, it travels on the surface of the buccinator and a little higher is crossed by the zygomaticus major muscle. In the interval between these two muscles it is covered only by skin and superficial fascia. Its accompanying veins lie behind it on the masseter. The cervical branch of the facial nerve enters the face superficial to the artery. A rich anastomosis occurs between the vessels of the two sides, and an additional anastomosis exists between the facial artery and the arteries which accompany the cutaneous branches of the 5th nerve on the face (ophthalmic and internal maxillary arteries). The facial artery supplies superior and inferior labial arteries which pass medially in the upper and the lower lips; they are situated in the submucous tissue about XA inch from the mucocutaneous junction, where their pulsations can be felt easily. Each anastomoses with its fellow of the opposite side and forms an arterial ring around the lips. During operations these vessels may be controlled by grasping the lip between the fingers and the thumb. The superior labial artery supplies a small branch to the nasal septum. Because of the marked vascularity, extensive areas of facial skin, torn in lacerating wounds, often retain their viability and may be sutured back into place. The anterior facial vein is the companion vein of the facial artery. It is formed near the inner angle of the eye by the union of the supra-orbital and supratrochlear veins and passes behind the artery, taking a less tortuous but more superficial course. It makes three important connections: with the diploic veins through the frontal diploic veins; with the pterygoid plexus through the deep facial veins; and with the cavernous sinus through the superior ophthalmic vein. The vein itself terminates in the internal jugular vein. The important relationship between this vessel and the "dangerous area" of the face has been stressed.

Nerves. The nerves of the face are branches of the facial, which supplies the muscles of expression, and the trigeminal, which supplies the integument and the muscles of mastication. The entire skin of the face, with the exception of the area over the lower half of the ramus of the mandible, which is supplied by the great auricular nerve, is innervated by the 3 divisions of the trigeminal nerve. Since the face is developed from 3 rudiments, the frontonasal, the maxillary and the mandibular processes, each possesses its own sensory nerve. These nerves make up the 3 divisions of the trigeminal: the ophthalmic, the maxillary and the mandibular. The ophthalmic, or first division of the trigeminal nerve, has 5 cutaneous branches:

(1) The supra-orbital nerve leaves the orbit through the supra-orbital notch or foramen about 2 finger-breadths from the median line. It divides into lateral and medial branches which supply the central portion of the upper eyelid, and then ascends to innervate the skin of the forehead and the scalp as far back as the vertex. It is accompanied by the supraorbital branch of the ophthalmic artery.

(2) The supratrochlear nerve emerges about one fingerbreadth from the median plane and supplies the medial part of the upper eyelid and a small area of the forehead above the root of the nose.

(3) The infratrochlear nerve emerges from the orbit above the

112 HEAD: Face medial palpebral ligament and supplies a small area of skin around the upper eyelid and the adjacent part of the nose.

(4) The external nasal nerve emerges on the face at the lower border of the nasal bone and supplies the skin of the nose as far down as its tip.

(5) The lacrimal nerve supplies the lateral part of the upper eyelid and the corresponding part of the conjunctiva. At times a nasociliary division of the ophthalmic nerve is described; it has been referred to in this text as the infratrochlear

or the external nasal nerve. The maxillary, or second division of the trigeminal nerve, has the following branches:

(1) The infra-orbital nerve, a direct continuation of the maxillary, emerges from the

infra-orbital foramen, passes under cover of the levator labii superioris and is accompanied by a small artery. It divides into terminal branches: the palpebral for the

lower lid, nasal for the posterior part of the nose, labial for the upper lip, and buccal

for the cheek.

(2) The zygomaticojacial nerve appears through the foramen of the same name as a twig and supplies the skin over the bony prominence of the cheek.

(3) The zygomaticotemporal nerve passes through the foramen of the same name,

pierces the temporal fascia near the zygomatic bone and supplies the skin of the

anterior part of the temple.

The mandibular, or third division of the trigeminal nerve, has 3 branches which reach the skin:

(1) The mental nerve emerges through the mental foramen and is situated deep to the depressor anguli oris; it sends its terminal branches to the lower lip, the chin and the skin over the body of the mandible.

(2) The buccal nerve appears at the anterior border of the ramus of the jaw below the

level of the parotid duct and travels almost to the angle of the mouth. It supplies the

skin over the cheek, and the branches that pierce the buccinator supply the mucous

membrane of the cheek.

(3) The auriculotemporal nerve is accompanied by the superficial temporal artery and passes under cover of the parotid gland. As its name implies, it supplies cutaneous branches to the auricle and the temporal region, but it also supplies the modified skin which lines the external auditory meatus and cover the outer surface of the tympanic membrane. The terminal branches on the scalp may reach as high as the vertex.

The mandibular nerve supplies the skin over the lower jaw but extends onto the external ear and upward to the side of the head. The branches of the 5th nerve which appear on the face communicate with branches of the 7th. For this reason a lesion in the territory of the 5th may cause a reflex spasm involving the facial muscles and producing a so-called facial tic. These conditions are treated best by removing the irritating cause, but they may require temporary interruption of the reflex arc by crushing the 7th nerve where it leaves the stylomastoid foramen. Trigeminal neuralgia is manifested by acute pain in the parts supplied by branches of the 5th nerve and may be due to carious teeth, sinus disease or irritative lesions within the cranium. In some cases of intractable neuralgia where all sources of possible peripheral irritation have been removed, it may be necessary either to resect nerves where they leave their bony canals or inject them with alcohol. If a lesion completely involves the 5th nerve, an extensive anesthesia of the same side of the face results which extends exactly to the midline. The muscles of mastication of the same side are also paralyzed, but the buccinator, which is supplied by the 7th nerve, remains intact. If only the 1st and the 2nd divisions of the 5th nerve are severed, the loss is entirely sensory, but if the 3rd division is cut, there is a sensory loss as well as a paralysis of mastication.

The facial nerve, supplying motor branches to the muscles of expression, also sends fibers to the stapedius, the stylohyoid, the posterior belly of the digastric, the scalp muscles, the auricle and the face, including the buccinator and the platysma; it provides secretory fibers to the salivary glands and sensory (taste) fibers to the tongue and the palate. Developmentally, the 7th is the nerve of the hyoid arch; therefore, it supplies all the muscles derived from it. It leaves the skull at the stylomastoid foramen, turns forward, laterally and slightly downward, then enters the parotid isthmus and passes be- tween fhe superior and the deep lobes of the gland. It lies superficial to the external carotid artery and the posterior facial vein and may be injured in operations in this region or on the parotid gland. The terminal branches of the nerve appear at the margins of the parotid and spread like the rays of an open fan or a goose's foot (pes anserinus). The 5 terminal branches are: (1) The temporal branch appears at the upper border of the gland and runs upward and forward to supply the facial muscles above the zygoma and the frontalis muscle. (2) The zygomatic branch emerges from the anterior border of the parotid abovethe parotid duct and supplies the muscles below the eye. (3) The buccal branch passes below the duct and supplies the buccinatorand the orbicularis oris; it communicates with the buccal branch from the mandibular division of the trigeminal nerve. (4) The mandibular branch emerges still lower and supplies the muscles of the chin and the lower lip. (5) The cervical branch appears at the lower end of the parotid, passes within a fingerbreadth of the angle of the jaw between the platysma and the deep fascia, supplies the platysma and then sends twigs up to the muscles of the lower lip. Coleman believes that there is a complicated and intricate intermingling of the various branches of the facial nerve so that the fibers meant for one group find their way toanother.

 

CLINICAL AND SURGICAL CONSIDERATIONS

Trigeminal Neuralgia. Trigeminal neuralgia (tic douloureux, facial neuralgia) is a neuralgia of the 5th cranial nerve which is associated with severe pain along one or more of its divisions. Some surgical measures have been adopted to alleviate or cure the condition,among them alcohol injection into the nerve or into the gasserian ganglion and, ifthis fails, division of its sensory route. Most authorities have abandoned operations on theganglion, since good results are obtained by section of the sensory root. The first division of this nerve is rarely at fault, but involvements of the 2nd and the 3rd divisions are frequent.

Injection of the Maxillary Nerve. Injectionof the maxillary nerve should be done where the nerve emerges from the foramen rotunduminto the pterygopalatine fossa. Two points should be marked the first is marked in the angle between the anterior border of the coronoid process and thelower border of the zygomatic arch; the second is marked in the angle between the upper border of the zygoma and its frontal process. Then these two lines are joined by a straight line, and a needle is inserted at the first point and passed upward and inward at an angle of 45° with the horizontal. The needle is kept in the direction of the line constructed and passes behind the mandible to enter the pterygopalatine fossa. It will strike the bone which forms the margin of the foramen rotundumabout 2 or 3 inches from the surface. The injection, first of procaine and then of alcohol, is made at this point.

Injection of the Mandibular Nerve This is done at the foramen ovale. The needle is inserted at the center of and under the zygomatic arch and then directed slightly forward. It will strike the outer lamella of the pterygoid process. Then the needle is withdrawn slightly and directed backward, where it will enter the foramen ovale. Injection of the Gasserian (Semilunar) Ganglion This is made through the foramen ovale and is done in the following way: a mark is made on the skin of the face about 3 cm. to the side of, and a similar distance above, the angle of the mouth. An imaginary line is drawn from this proposed point of entrance to the pupil, and a second line is drawn from this point to the auricular tubercle of the same side. The needle is introduced and advanced toward the center of the zygomatic arch in the plane joining the point of entry of the needle to the pupil when the patient is viewed from the front. The needle strikes the infratemporal bony plane and then is withdrawn gently and pushed up in a more posterior direction; this is continued until, when viewed from the front, the needle is in the plane of the first line and, when viewed from the side, in the plane of the second line. It then enters the foramen ovale and there will encounter the ganglion. Division of the sensory root of the 5th nerve was perfected by Frazier. A vertical incision is made which divides the skin, the temporal fascia and the underlying muscle. The periosteum is incised and detached from the temporal bone by means of a periosteal elevator; a burr hole is made through the temporal bone and enlarged with bone forceps. The dura is separated from the base of the skull, and a retractor elevates the brain from the base of the middle fossa. The middle meningeal artery is exposed, cut and ligated as it emerges into the middle fossa through the foramen spinosum. The dura is stripped until the 3rd division of the 5th nerve and the edge of the foramen ovale are exposed; the sheath of the nerve is incised and gently pushed upward and backward until the gasserian ganglion is seen. A small flap of arachnoid is turned downward, exposing the fan-shaped fibers of the sensory root. The sensory fibers are drawn outward, exposing the motor root. The sensory root is divided behind the ganglion.

 

 

FIG. Injection of the maxillary and the mandibular nerves: (A) direction of needle for the injection of the maxillary and the mandibular nerves (B) injection of the mandibular nerve.

 

 

MUSCLES

The facial muscles are placed around the orifices of the eye, the ear, the nose and the mouth and act as sphincters or dilators

 

 

FIG. Injection of the gasserian ganglion.

 

All are innervated by the 7th (facial) nerve. It is extremely difficult to memorize this confusing group; hence, it is best to locate two landmarks around which the muscles are arranged. The two landmarks are the two orbicularis muscles, namely, the orbicularis oculi and the orbicularis oris. Two muscles are associated with the nose, two muscles with the zygoma, two are levators of the lip, two are at the angle of the mouth, two are placed at the lower lip, and the two remaining muscles are associated with the chin and the cheek.

 Orbicularis Oculi. This muscle has 3 parts, namely, the orbital, the palpebral and the lacrimal. The orbital portion passes in circular form from the medial palpebral ligament and the adjacent part of the frontal bone across the forehead, the temple, the cheek and back to the medial ligament where it started. Since these fibers have no lateral attachments, they draw the lids medially. They are responsible for the "crow's feet" usually seen at the lateral angles of the eye. The palpebral portion, arising from the medial palpebral ligament, which is a short fibrous cord stretched horizontally from the medial commissure of the eyelids to the adjoining part of the maxilla, curves laterally in both eyelids. The fibers of this part are inserted into the lateral palpebral raphe and are located within the lid proper and in front of the palpebral fascia.

 

 

FIG. Division of the sensory root of the trigeminal nerve.

 

They usually act involuntarily and close the lids in sleeping and in blinking. The lacrimal part (Homer's muscle, tensor tarsi) is made up of fibers which pass medially behind the tear sac and attach to the posterior lacrimal crest, keeping the lids closely applied to the eyeballs. This part of the orbicularis oculi can also contract independently of the other two portions, and by this independent action wrinkles the skin around the eye, giving partial protection from light or wind. Those fibers which insert into the skin of the eyebrow draw it down as in frowning and also draw the eyebrows closer together, producing one or more vertical furrows in the middle of the forehead. Orbicularis Oris. This sphincter muscle of the mouth forms the greater part of the substance of the lips. Its fibers encircle the oral aperture and extend upward to the nose and downward to the groove which is situated between the lower lip and the chin. Many of its fibers are derived directly from the buccinator; others from the depressors and the elevators of the angles of the mouth. This complex arrangement makes possible the varied movements of the lips, such as, pressing, closing, pursing, protruding, inverting and twisting. Muscles Associated With the Nose. These two muscles are the procerus and the compressor nares. The procerus muscles unite. They arise from the fascia covering the lower parts of the nasal bones, broaden and insert into the skin between and above the eyebrow. Their fibers interlace with the frontal bellies of the occipitofrontalis.

 

 

FIG. The muscles of the face.

 

 

FIG.The parotid gland: (A) superficial relations, (B) the most common pattern formed by the fine branches of the facial nerve.

 

By their contraction they draw down on the skin of the root of the nose and produce transverse wrinkling. The compressor nares muscle originates from the side of the bony aperture of the nose and spreads out as a fan-shaped muscle just above it. It joins its fellow of the other side, thus forming a sling across the bridge of the nose. It compresses the nostril, and its action is especially well demonstrated in the crying of infants. (Two other muscles, the dilator naris and the depressor septi nasi, are also found in this area but are small and clinically unimportant.)

Muscles Associated With the Zygomatic Area. These two muscles are the zygomaticusminor and the zygomaticus major.The zygomaticus minor arises from the zygomatic bone and is closely related to the lateral margin of the levator labii superioris. This is a mere muscular slip and is often absent. The zygomaticus major is both longer and thicker than the minor and runs obliquely from the zygomatic bone to the angle of the mouth. The major has been referred to as the "smiling muscle." Lip Elevators. These two muscles are the levator labii superioris alaeque nasi and the levator labii superioris. The levator labii superioris alaeque nasi is a small muscle lying along the attachment of the nose; it divides and inserts into the ala and the upper lip. It aids in dilation of the nostril and elevates the upper lip. The levator labii superioris muscle is thin, fairly wide and descends from the infraorbital margin into the upper lip. It is overlapped by the orbicularis oculi.

Muscles Associated With the Angle of the Mouth. These two muscles are the levator anguli oris (caninus) and the depressor anguli oris (triangularis). The levator anguli oris lies deep to the levator superioris; it arises from the upper jaw below the infra-orbital foramen, inserts partly into the skin of the angle of the mouth and blends with the orbicularis oris. It also lies deep to the zygomatic major. The depressor anguli oris muscle is placed superficially. It is triangular in shape, its base corresponding to its insertion in the neighbourhood of the angle of the mouth.

 

 

FIG. Deep relations of the parotid gland: (A) the ramus of the mandible has been cut across transversely, showing the superficial and deep lobes of the gland connected by the isthmus; (B) venous pattern commonly found in the gland substance.

 

Muscles Associated With the Lower Lip. These two muscles are the risorius and the depressor labii inferioris. The risorius lies horizontally opposite the angle of the mouth but may be continuous with the posterior fibers of the platysma or may arise independently from the fascia covering the masseter muscle. Its fibers converge at the angle of the mouth, where they are inserted into the skin. By drawing the angle of the mouth in a lateral direction, the muscle plays a large part in the production of a smile and has been referred to as the "grinning muscle." The depressor labii inferioris muscle is short and wide, lies in front of the depressor anguli and is overlapped by it. Its medial groove meets and decussates with that of its fellow above the transverse groove on the lip, leaving a triangular space which is filled by the mentalis.

Muscles Associated With the Chin and the Cheek. The mentalis muscle passes from the lower incisor downward to the skin over the chin. When it contracts, it raises the skin over this area, thereby accentuating the transverse fold. The buccinator muscle is situated more deeply and forms the fleshy stratum of the cheek. Its fibers pass horizontally forward to the angle of the mouth. The mucous membrane of the cheek and the lips lines its inner surface. The muscle arises from the alveolar margins of both upper and lower jaws external to the molar teeth and more posteriorly from the pterygomandibular raphe. The uppermost and lowermost fibers pass directly into the upper and the lower lips, respectively; but the middle fibers decussate, the upper half running into the lower lip and the lower half into the upper lip. At the angle of the mouth the muscle blends with the orbicularis oris. It retracts the mouth angle and therefore is considered as the antagonist of the orbicularis oris. Since the buccinator is supplied by the facial nerve, it is not classified as a muscle of mastication; however, it is used during mastication to press the cheek against the teeth and to prevent the food from escaping into the vestibule of the mouth. It also aids in the action of blowing and sucking. The buccopharyngeal fascia is a thin sheet that clothes the surface of the buccinator muscle and extends  ackward to cover the constrictor muscles of the pharynx. The parotid duct on its way to the vestibule of the mouth pierces this fascia, the buccinator and the mucous membrane of the mouth. The buccal fat pad, also referred to as the suctorial pad, is situated on the buccinator muscle. It is a mass of fat, encapsulated in fascia, which lies on the muscle partly tucked in between the buccinator and the masseter. The buccal nerves, small vessels and the parotid duct pierce it. It thickens the cheek and helps to reduce atmospheric pressure during sucking. It is much larger in infants than in adults, and the rounded fullness of a baby's cheek is largely due to it.

PAROTID REGION Although the parotid gland may be considered as a constituent of the neck, its relations to the face are more numerous and of greater practical importance.

PAROTID GLAND The parotid gland is the largest of the salivary glands; it fills the parotid space and sends a process forward over the masseter muscle. Its fibrous capsule sends septa into the interior of the gland, dividing it into lobules and making removal difficult at times. In this respect it differs from the submaxillary gland, which is loosely enveloped and easily shelled out. In front of the styloid process and from the medial surface of the gland is a pharyngeal prolongation which is closely related to the wall of the pharynx and to the great vessels in the parapharyngeal space. The fascial septum separating this aspect of the gland from the carotid sheath may be broken through by pathologic erosions or malignant tumors as well as sharp instruments. The parotid gland has the following relationships: superficially, it is covered by skin, superficial fascia lymph glands, fibrous capsule and branches of the great auricular nerve. The upper border is in contact with the external auditory meatus and the temporomandibular joint; abscesses of the gland  may perforate into either of these structures. The anterior border is grooved by the masseter, the ramus of the mandible and the internal pterygoid muscle. The posterior border is in contact with the mastoid process and the sternocleidomastoid muscle. The lower border overlaps the internal and the external carotid arteries and the internal jugular vein. The deep surface is in contact with the digastric and the styloid muscles, the internal and the external carotid arteries, and the 9th, the 10th, the 11th and the 12th cranial nerves. Confusion still exists concerning the relationship between the facial nerve and the parotid gland In 1912 Gregoire described a superficial and a deep lobe of the parotid gland joined by an isthmus that was situated above the facial nerve. In 1917 McWhorter also described two lobes, but, in his opinion, the isthmus lay between the main divisions of the nerve. In 1945 McCormack, Cauldwell and Anson confirmed this work. In 1948 McKenzie stated that there were several isthmuses connecting the superficial and the deep lobes of the parotid gland. The branches of the facial nerve passed between these isthmuses so that the superficial and the deep lobes of thegland could be joined at various locations.

 

 

FIG. Some of the variations between the parotid gland and the facial nerve. A. The two parotid lobes are united by an isthmus. B. The lobes are united above. C. A combination of a and b D. No division into superficial and deep lobes. The nerve courses through the "one-lobed" parotid gland.

 

It is difficult to determine which of these views is correct, and the surgeon working in this area will have to keep the various patterns in mind as he performs surgery on the parotid gland. The socia parotidis is an accessory part of the parotid gland which lies immediately above its duct and on the masseter muscle. The fibrous capsule of the parotid is derived from the investing layer of deep cervical fascia which splits at the lower pole of the gland to ensheath it. The deeper of these two layers passes under the gland and attaches to the base of the skull; the superficial layer passes anterior to the masseter muscle and attaches to the lower border of the zygomatic arch. This layer has been referred to as the parotideomasseteric fascia and accounts for the intense pain caused by inflammatory swellings of the gland. That part of the fascia which connects the styloid process to the angle of the mandible has been called the stylomandibular ligament and separates the parotid and the submaxillary glands.

 Nerve and Blood Supply. The  uriculotemporal nerve is a sensory branch of the mandibular division of the 5th, which supplies the skin in front of the ear. Its course is as follows: ascending upward through the temporal region to the vertex of the skull, the nerve emerges from the upper border of the parotid, crosses the root of the zygoma between the external ear and the condyle of the jaw and divides into its temporal branches. It may be compressed by tumors or swellings in the parotid gland and produce exquisite pain radiating over the temple as high as the vertex. The 7th or facial nerve, emerging from the stylomastoid foramen, divides into its two main branches, which embrace the isthmus of the parotid gland. From here these branches redivide and radiate from the border of the gland in the form of a goose's foot (pes anserinus). This has been discussed elsewhere. Although veins are variable, they follow a fairly constant course in the substance of the parotid gland. The posterior facial vein aids in the formation of two other veins—the external jugular and the common facial. At its lower end and while in the parotid, the posterior facial divides into an anterior and a posterior branch. The anterior branch joins the anterior facial vein to form the common facial, and the posterior joins the posterior auricular to form the external jugular vein. The external carotid artery ascends from under cover of the digastric and the stylohyoid muscles and comes into relationship with the posteromedial surface of the parotid. Here it gives rise to a-posterior auricular artery and then enters the gland, passing from the posteromedial to its anteromedial surface. At the back of the neck of the mandible it divides into internal maxillary and superficial temporal branches. The superficial temporal artery arises under cover of the parotid gland, emerges at its upper border, accompanied by a corresponding vein and the auriculotemporal nerve. It ascends across the root of the zygoma, where its pulsations may be felt readily; it continues upward on the temporal fascia and divides into anterior and posterior branches, which supply the scalp. In addition to many small branches which supply the parotid gland, the auricle and the facial muscles, the superficial temporal supplies a transverse facial artery which runs forward on the masseter muscle, emerges at the anterior border of the gland and continues parallel with and above the parotid duct. The lymph glands of the parotid region may be divided into two groups: a superficial, which is superficial to the parotid sheath and constitutes the preauricular group draining the temporal and the frontal regions of the scalp, the outer portion of the eyelid and the outer aspect of the ear. A deeper group makes up the parotid group, which is scattered through the gland substance and drains the upper and posterior parts of the nasopharynx, the soft palate and the middle ear. These relationships are important because swellings of the parotid gland may be confused with enlarged and infected lymph glands in this region.

Parotid (Stensen's) Duct. The duct of the parotid gland begins at the anterior part, passes forward on the masseter muscle about one fingerbreadth below the zygoma and is accompanied by the transverse facial artery above and the buccal branch of the facial nerve below. It bends abruptly around the anterior border of the masseter, pierces the substance of the buccinator muscle, runs obliquely forward between the buccinator and the mucous membrane of the mouth and opens on a papilla opposite the upper 2nd molar tooth. It may be felt best when the jaws are clenched, because it then can be rolled against the tense masseter muscle. The duct is about 2 ½ inches long and 1/8 inch in diameter, its orifice being its narrowest part. The bend the duct makes

 

 

FIG. Parotidectomy: (A) Incision which also may be utilized for preliminary ligation of the external carotid artery. (B) Mobilization of the superficial lobe. The numbers indicate the order in which this dissection takes place. (C) Division of the isthmus. The operation may end at this stage if only the superficial lobe is involved, or it may be continued by putting traction on the isthmus and removing the deep lobe. The branches of the facial nerve are visualized and protected.

 

around the anterior border of the masseter may be so sharp that the buccal segment remains at right angles to the masseteric part. This should be kept in mind if a probe is passed along the duct from the mouth. Its course can be marked by the middle third of a line which joins the lobule of the ear to the midpoint between the red margin of the upper lip and the ala of the nose.

 

SURGICAL CONSIDERATIONS

PAROTIDECTOMY Most authorities believe that mixed tumors of the parotid gland are potentially malignant and, therefore, should be subjected to complete extirpation. In total parotidectomy, a long incision is made in front of the ear and as close as possible to the cartilage. The inferior end of this incision turns around the lobule, extends to the mastoid process and then downward along the anterior border of the sternocleidomastoid muscle. Bailey is of the opinion that one of the first steps should be the ligation of the external carotid artery, which makes the operation easier and safer. The anterior skin flap is reflected forward to the mandible. The submaxillary salivary gland within its capsule is utilized as a landmark, and the posterior belly of the digastric is identified. Mobilization of the superficial parotid lobe is the next step and is accomplished best by commencing at the anterior extremity of its lower border. Sistrunk has advised isolating the inframandibular branch of the facial nerve first as it passes along the angle of the jaw, but many surgeons have found difficulty in locating the nerve before the gland has been properly freed. The anterior extremity of the lower border is considered a safe area and is an excellent place to commence dissection. After freeing this corner, a new dissection is started at the extreme posterior end of the upper border of the gland. The ear is retracted backward, and a cleavage plane is found which allows the gland to be dissected upward and forward. In this location the temporal artery is found, but if the external carotid has been ligated, the temporal can be dissected up with the parotid gland or left in situ, whichever is easier. The dissection continues along the upper border, and the gland is lifted from the zygomatic arch. At this stage a sharp lookout is kept for the uppermost part of the pes anserinus. It is important to preserve the upper branches that go to the orbital region. These lie on the masseter muscle, and once the correct cleavage plane is found, there is no great difficulty, since the nerves have a tendency to adhere to the muscle rather than the gland. As the dissection continues along the anterior border, Stensen's duct and at times the socia parotidis are freed from the masseter. In the middle region the mid-portions  of the pes are seen and freed as far as possible.The antero-inferior border of the gland which was mobilized as the first step is now grasped and retracted upward. Dissection then proceeds toward the mastoid process, using the digastric muscle as a guide. At this step the main trunk of the facial nerve usuallycan be identified. With this under vision and the gland mobilized on all sides, the isthmus and its limitations can be made out by vision or palpation. Then the free superficial lobe is retracted forward, and the isthmus is divided from behind forward. This having been done, the facial nerve and its divisions will usually become apparent. Stensen's duct is divided, if this has not been done already. The facial nerve can be held aside by fine retractors or ligatures passed beneath it, and the deep lobe is removed by separating it from the great vessels of the neck and the pharyngeal wall. Sometimes bleeding occurs from the large tributaries of the jugular vein during this stage and it may become necessary to ligate the jugular. The surgeon must remember that this is only one of many technics described. The various anatomic descriptions of this region resulted in different surgical approaches. Eddey has presented an operation in which he described three isthmuses of the parotid gland, stating that the facial nerve is completely surrounded by glandular tissue. Riessner uses the so-called "upper branch" of the facial nerve as a safe guide for parotid gland removal. Many other technics can be studied by anyone interested in the surgery of this area.

PAROTID ABSCESS A parotid abscess may be drained through an incision (Blair) which commences about 1 inch anterior to the ear and is carried downward behind and below the angle of the jaw. This is deepened through the capsule of the gland, and then the parenchyma can be opened by blunt dissection. The deep part of the gland may be drained by lifting the lower pole forward. It may become necessary to drain the space between the masseter and the superficial lobe of the gland, and this too can be accomplished through the same incision. Some surgeons have advised the use of a horizontal incision for the drainage of such an abscess.

 

 

FIG. The 6 muscles of mastication. (A) Viewed from left side; the zygomatic arch and part of the mandible have been removed. The temporal muscle has been cut for the purpose of exposing the pterygoid muscles. (B) Viewed from below

 

 

FIG. The internal maxillary artery. The vessel is divided into 3 parts by the external pterygoid muscle. Part I is known as the mandibular portion; Part II, the pterygoid; and Part III, the pterygopalatine portion. The branches of each part are numbered and

represented.

 

VESSELS AND NERVES

Internal Maxillary Artery. This artery arises from the external carotid opposite the neck of the mandible and under cover of the parotid gland. It passes forward deep to the neck of the bone and superficial to the sphenomandibular ligament. Between the mandible and the sphenomandibular ligament it is accompanied by its vein and lies superficial to the inferior alveolar (dental) nerve. It goes upward and forward superficial to the external pterygoid between it and the temporal muscle, or deep to the external pterygoid, between it and branches of the mandibular division of the 5th nerve. It then passes medially between the two heads of the pterygoid and through the pterygomaxillary fissure into the pterygopalatine fossa, to end in its numerous terminal branches. The external pterygoid muscle divides the maxillary artery into three parts. The first is known as the mandibular portion; it lies between the neck of the mandible and the sphenomandibular ligament, taking a horizontal course forward nearly parallel with and a little below the auriculotemporal nerve. In this location it is imbedded in the parotid gland and usually crosses in front of the inferior alveolar nerve. The second part is called the pterygoid portion, and here the artery may lie lateral or medial to the external pterygoid muscle. This part of the artery usually runs obliquely forward and upward under cover of the ramus of the mandible and passes on the superficial surface of the muscle. The vessel then passes between the two heads of origin of this muscle and enters the pterygopalatine fossa. Part three of the vessel, the pterygopalatine portion, lies in the pterygopalatine fossa in relation to the sphenopalatine ganglion. The branches which arise from the first part of the artery are associated with foramina; those which come from the second part are associated with muscles, and the branches of the third part are again associated with foramina. The branches of the first part of the internal maxillary artery are: 1. The deep auricular artery, which passes to the external auditory meatus. 2. The anterior tympanic, which enters the pterotympanic fissure to the middle ear. 3. The middle meningeal, which arises from the upper border of the maxillary bone and runs upward and deep to the external pterygoid muscle. As it ascends it is embraced by the two heads of the auriculotemporal nerve; it enters the middle cranial fossa through the foramen spinosum and upward and forward on the squamous temporal and great wing of the sphenoid bone toward the antero-inferior angle of the parietal bone, where it divides into anterior and posterior branches. The anterior branch travels upward across the great wing of the sphenoid toward the pterion and then on the parietal bone behind the coronal suture near the motor cortex. The posterior branch passes upward and backward on the squamous temporal to the middle of the lower border of the parietal bone and then breaks up into its terminal branches. 4. The accessory meningeal, also referred to as the small meningeal artery, has a similar course and may be a branch of the above-mentioned vessel; it enters the middle cranial fossa through the foramen ovale and supplies the dura mater and the trigeminal ganglion. 5. The inferior alveolar (dental) artery passes downward behind the inferior alveolar nerve and between the sphenomandibular ligament and the mandible. It supplies a mylohyoid branch and then enters the mandibular foramen to supply the teeth and the lower jaw. Its terminal branch appears on the face accompanied by the mental nerve. There are 4 branches of the second portion of the internal maxillary artery: 1. The masseteric artery passes laterally through the mandibular notch to the masseter muscle and also supplies the mandibular joint. 2. The deep temporal has 2 branches, anterior and posterior, which ascend between the temporalis muscle and the pericranium; they supply the muscle and anastomose with the middle temporal artery. 3. The pterygoid arteries are irregular in number and origin and supply the pterygoid muscles. 4. The buccinator (buccal) artery travels forward with the buccal nerve between the internal pterygoid and the jaw to supply the buccinator muscle, the skin and the mucous membrane of the cheek. The 6 branches of the third portion of the internal maxillary artery are: 1. The posterosuperior alveolar, which descends over the posterior surface of the maxilla, sends branches to the gums, the buccinator muscle, through the bone to the molars, the premolars and the maxillary sinus. 2. The infra-orbital artery, really a continuation of the parent trunk, is accompanied by the maxillary nerve through the infraorbital canal, appearing on the face beneath the levator labii superioris. In the canal it sends branches to the orbit and an anterior dental branch which accompanies the nerve and supplies the front teeth. On the face it supplies the lacrimal sac and the medial angle of the orbit.

 

 

FIG. The lingual and the inferior alveolar (dental) nerves.

 

3. The greater palatine artery passes through the greater palatine canal with the nerve of the same name, then along the hard palate in a groove about 1/2 inch from the teeth, and finally through the lateral incisive foramen to the nose. 4. The pharyngeal artery is very small and passes backward through the pharyngeal canal accompanied by the pharyngeal nerve. It is distributed to the upper part of the pharynx and the auditory tube. 5. The artery of the pterygoid canal (Vidian) passes backward along the pterygoid canal with its corresponding nerve. It is distributed to the upper part of the pharynx and to the auditory tube, sending a small branch into the tympanic cavity which anastomoses with the other tympanic artery. 6. The sphenopalatine artery enters the nasal cavity through the sphenopalatine foramen and supplies the mucous membrane of the nasal cavity, the adjacent sinuses and the pharynx. At the back part of the superior meatus it supplies posterior lateral nasal branches which spread forward over the conchae and the meatus, anastomosing with the ethmoidal arteries and nasal branches of the descending palatine artery. It ends on the nasal septum as posterior septal branches which anastomose with the ethmoidal arteries and the septal branches of the superior labial. One branch descends in a groove on thevomer to the incisive canal and anastomoses with the descending palatine artery.

Pterygoid Venous Plexus. This rich network of veins is located around the lateral pterygoid muscle; veins corresponding to the maxillary artery empty into it. From its posterior end a maxillary vein passes backward to unite with the superficial temporal, forming the posterior facial vein. The plexus makes the following communications: with the cavernous sinus through the foramen ovale; with the anterior facial through the deep facial vein; with the inferior ophthalmic veins through the inferior orbital fissure.

Mandibular Division of the Trigeminal Nerve. In the parotid region this plays an important role. It leaves the skull through the foramen ovale in the greater wing of the sphenoid bone and differs from the other two divisions in that it is a mixed nerve. The sensory part arises from the gasserian ganglion, and the motor part is the motor root of the 5th nerve. The two roots pass through the foramen ovale and almost immediately unite into one trunk which is covered by the external pterygoid muscle. It lies on the surface of the tensor palati (veli palatina) muscle, which separates the nerve from the auditory (eustachian) tube and the nasopharynx. The middle meningeal artery lies lateral to and a little behind it. The trunk divides into anterior and posterior divisions. The undivided trunk gives off a recurrent nerve and the nerve to the internal pterygoid muscle. The recurrent nerve (nervus spinosus) passes back into the foramen spinosum and supplies the dura and the mastoid air cells. The nerve to the internal pterygoid muscle is self-explanatory. From the anterior division, mainly muscular, are derived the deep temporal, the masseteric, the external pterygoid and the long buccal branches. From the posterior division, mainly sensory,are derived the auriculotemporal, the inferior dental (alveolar) and the lingual nerves. Although the anterior division of this nerve gives off muscular branches to the temporal, the masseter and the external pterygoid muscles, the long buccal nerve is essentially sensory; it passes down between the two  eads of the external pterygoid muscle, pierces the anterior part of the temporal muscle, traverses the suctorial fat pad, and then branches outward to the skin of the face and inward to the mucous membrane of the cheek.

Auriculotemporal Nerve. This nerve has been discussed elsewhere. It is a sensory branch of the mandibular nerve which forms an anastomosis with the facial nerve and otic ganglion. It emerges from the upper border of the parotid and crosses the root of the zygoma between the external ear and the condyle of the jaw, where it divides into its temporal branches. This nerve is sometimes resected in persistent neuralgias and is easily found where it crosses the zygoma, lying between the ear and the temporal artery. By means of its communication with the otic ganglion, secretory fibers result;these supply the parotid gland; hence, the rationale for division of it in an attempt to close a parotid fistula. Auricular branches of this nerve pass to the upper ear and the external auditory meatus. Referred pain from these branches may be so severe that the ear drum may be opened unnecessarily when one of the molar teeth is at fault.

Lingual Nerve. This nerve passes downward deep to the external and on the surface of the internal pterygoid muscle. In this part of its course it is in front of the inferior alveolar nerve and is joined by the chorda tympani (7th nerve), which contains taste fibers that are carried by the lingual to the anterior two thirds of the tongue. As the nerve continues downward and forward it lies between the mandible and the internal pterygoid, and farther forward is under cover of the mucous membrane of the mouth on the superior constrictor and the stvloglossus muscles. It passes forward between the mylohyoid and the hyoglossus and arrives between the sublingual gland and the genioglossus muscle, where it crosses the submandibular duct and supplies the gums and the anterior two thirds of the tongue. One should not be confused between taste and sensation if one recalls that the lingual nerve supplies the anterior two thirds of the tongue with its sensory fibers, but this nerve carries fibers from the facial nerve by way of the chorda tympani, which supply taste fibers to the same region of the tongue. Resection of the lingual nerve is at times necessary for the relief of intense pain which is associated with carcinoma of the tongue.

Inferior Alveolar (Dental) Nerve. This nerve passes downward deep to the external pterygoid muscle but superficial to the sphenomandibular ligament and is accompanied by the dental vessels. Immediately before entering the mandibular foramen it gives off the nerve to the mylohyoid muscle; this descends in a groove on the deep surface of the mandible in company with the mylohyoid vessels.

 

 

FIG. The temporomandibular joint: (A) lateral view, right side; (B) exposure of the joint and the articular disk, following removal of the temporomandibular ligament and part of the condyle of the mandible; (C) medial view, showing the stylomandibular and the sphenomandibular ligaments.

 

This nerve reaches the posterior edge of the mylohyoid, passes superficial to that muscle and ends by supplying the mylohyoid and the anterior belly of the digastric. In the inferior dental canal it sends branches to the roots of the lower teeth and gums. The nerve finally emerges through the mental foramen as the mental nerve.

TEMPOROMANDIBULAR JOINT The temporomandibular (temporomaxillary, mandibular) is a synovial joint that is formed by the head of the mandible with the articular fossa and the eminence of the temporal bone. The articulating surfaces are completely separated by an articular disk which divides the joint cavity into an upper and a lower chamber. The joint is surrounded by a lax capsule which envelops the bony articular surface and furnishes attachment to the interposed cartilage. The laxity of this capsule enables free joint movements. Over its lateral aspect the capsule is markedly thickened and strengthened by the temporomandibular ligament (external lateral ligament), which stretches from the zygoma and the tubercle at its root to the lateral and the posterior surfaces of the neck of the mandible. The ligament is covered by the upper part of the parotid gland and is in relation to the superficial temporal vessels. The articular disk is attached around its circumference to the capsular ligament. However, there is an exception to this attachment, since the disk receives part of the insertion of the external pterygoid muscle in front. The lower disk surface is concave to fit into the head of the mandible, but its upper surface undulates to fit the fossa and the eminence. The disk can become loose or detached and, as it slips back and forth, may produce an audible click (clicking jaw). At times it may become detached at one end and is then apt to double on itself, in which event it becomes impacted between the joint surfaces and causes locking; the symptoms may become so discomforting and embarrassing that removal of the disk is necessary. Two accessory ligaments described as bands and giving additional ligamentous support to the joint are the sphenomandibular and the stylomandibular. The sphenomandibular ligament (internal lateral ligament) lies on a deeper plane than the joint, distinct from the medial part of the articulation, and is a thin and fairly long band stretching from the spine of the sphenoid bone to the edge and the margins of the mandibular foramen Medially, its upper part is separated by fat from the wall of the nasopharynx, and its lower part lies on the internal pterygoid muscle. Laterally, it is related to the mandibular joint, and the mandible is separated from the ligaments, from above downward, by the auriculotemporal nerve, the external pterygoid muscle, the maxillary vessels and the inferior dental vessels and nerves. Although these structures separate the ligament from the joint, the chorda tympani nerve lies deep to the ligament. The stylomandibular ligament is a thickened part of the cervical fascia that covers the deep surface of the parotid gland. It extends from the styloid process to the posterior border and angle of the mandible and separates the parotid from the submandibular gland. The synovial membrane is in two separate parts, since it has two separate cavities to line. The upper synovial cavity is the more extensive because of the greater size of the articular fossa of the temporal bone. The membrane, although reflected onto the articular disk, disappears from this part in the adult. The construction of the temporomandibular joint permits a wide range of movements. Elevation is produced by the masseter, the internal pterygoid and the temporalis muscles; depression by the digastric, the mylohyoid, the geniohyoid and the platysma, protrusion by the pterygoids, the anterior part of the temporalis and fibers of the masseter; retraction by the posterior fibers of the temporalis and the deeper fibers of the masseter. Grinding movements are produced by the pterygoids of opposite sides acting alternately.

 

 

FIG. Anterior dislocation of the mandible. The condyle has been drawn over the articular eminence into the zygomatic fossa by the contraction of the external pterygoid. Then the mandible is drawn upward and fixed in place by masseter, internal pterygoid and temporalis muscles.

 

The construction of the joint permits a forward dislocation, either unilateral or bilateral, which can occur when the mouth is widely opened. Such dislocations have occurred during a blow struck on the lower front teeth, or during laughing, yawning, vomiting and also in the dentist's chair. When the mouth is opened widely, the condyles and the interarticular fibrocartilage glide forward. Normally, the condyles should not reach as far as the summit of the articular eminence, but when the mouth is opened widely all parts of the capsule except the anterior are made tense, and if at this time the external pterygoid muscle contracts vigorously, the condyle is drawn over the articular eminence onto the zygomatic fossa and the interarticular cartilage remains behind. As soon as it reaches its new position, it is drawn up immediately by

FIG. Sagittal section through the upper lip. The 5 layers which constitute each lip are shown.

 

FIG. Alveolar abscesses and their possible paths of invasion. In the upper jaw, the infection may spread to the external bony plate, into the mouth, the nasal cavity or the maxillary sinus. In the lower jaw, abscesses may burrow between periosteum and soft tissue, or between periosteum and bone, and then discharge on the neck, between the jaw and the chin; pus may also find its way to the floor of the mouth, resulting in Ludwig's angina.

 

the internal pterygoid, the temporal and the masseter muscles and is thereby spastically fixed in place.

 

 

FIG. The venous drainage of the teeth and possible paths of extension of a thrombophlebitis. The veins of the upper jaw drain in two directions: the anterior drains into the anterior facial vein, and the posterior into the pterygoid plexus. Following a tooth extraction, these infections may travel to the pterygoid or the pharyngeal plexus. Pterygoid plexus infections can extend to the inferior ophthalmic veins or through the foramina lacerum and ovale. In cavernous sinus thrombosis following anterior teeth infections, the thrombophlebitis usually spreads from the anterior facial vein through the orbit via the ophthalmic veins, usually the superior.

 

 

FIG. Infections about the face and the mouth: (A) the 3 muscular fascial spaces, (B) approach to abscesses above and below the geniohyoid muscle.

 

PRACTICAL CONSIDERATIONS

THREE MUSCULAR FASCIAL SPACES AND ONE VASCULAR VISCERAL SPACE

Coller and Yglesias have emphasized the fact that the fasciae in this region are attached to periosteum, enclose facial muscles and form closed spaces. In this way the spaces are separated from cervical fascial spaces, and infections do not spread into the neck but remain limited. However, the fasciae which surround the viscera and the vessels are continuous between the face and neck so that infections may travel from one to the other. These authors have described three muscular fascial spaces and one vascular visceral space.

Space of the Body of the Mandible. This fascial space exists between the superficial and the deep divisions of the middle muscular fascia. It has an important bearing on infections of this bone and, because of the fascial attachment, osteomyelitis of the body of the mandible is prevented from spreading either superficially or deep. An infection in this location may do one of three things: discharge into the mouth, spread to the masticator space, or remain localized. The space is drained through the mouth by means of an incision that goes through the gingival mucous membrane of the vestibule or by an incision through the skin along the inferior border of the body of the bone.

Masticator Space. The second space is occupied by the ramus of the mandible. It is bounded externally by the masseter, internally by the pterygoids and superiorly by the temporal muscle. Infections in this space may travel upward either to the so-called superficial or to deep temporal spaces. The temporal spaces may be drained by incisions that are carried through the skin, the subcutaneous tissue and the temporal fascia. If the malar bone or the zygoma are involved, resection of either may be necessary.

Parotid Space. This is the third fascial space of the face. It is occupied by the parotid gland. Drainage of this space can be accomplished by an incision that is made in front of the ear and passes downward behind and below the jaw. The external surface of the parotid is thus exposed without injury to the facial nerve if the dissection is kept external to the glandular substance. If it is desirable to drain the space between the masseter muscle and the superficial part of the parotid gland, a horizontal incision is made at the level of and parallel with the superior border of the mandible.

Visceral Vascular Fascial Space. This is the lateral pharyngeal space. It is bounded anteriorly by the medial wall of the masticator space, laterally by the parotid space, posteriorly by the carotid sheath and medially by the submaxillary gland. Since this is not one of the enclosed facial fascial spaces, infection may travel and involve the internal carotid artery, producing severe hemorrhage, or it can produce septic thrombosis of the internal jugular vein. Drainage may be external through the parotid space or internal through the lateral pharyngeal wall. Infection in this space can spread readily to the viscerovascular spaces of the neck and the mediastinum.

UPPER AND LOWER LIP INFECTIONS Infections in the upper lip should not be incised or squeezed. Many surgeons advocate ligation of the angular vein, but this is still a moot question. If pus is present, some advise drainage. Meningitis and the occurrence of cavernous sinus thrombosis should always be kept in mind.

Infections in the lower lip are less dangerous than those of the upper. Cavernous sinus thrombosis rarely occurs from infections in this region because the veins lie at a deeper level and are more efficiently splinted by muscle and bone. Two anatomic spaces are formed in the floor of the mouth. The superficial space lies between the genioglossus and the geniohyoid muscles and is divided into two compartments by a median fascial septum. The second space lies at a deeper level and is situated between the geniohyoid and the mylohyoid muscles. It, too, is divided in the middle by a fascial septum. Ludwig's angina constitutes involvement of these spaces, with elevation of the tongue and inflammation of the mucous membrane over the involved area. If the infection is unilateral, the tongue is pushed to the opposite side, but if bilateral, it is pushed upward toward the roof of the mouth. The treatment of Ludwig's angina consists of early drainage instituted in the involved space; hence, it is important to determine whether the abscess is below or above the geniohyoid. If the abscess is below this muscle, the region under the chin is prominent, and an incision should be made through the skin, the subcutaneous tissue and the mylohyoid muscle into the abscess cavity. If the swelling is diffuse, the incision should follow the lower border of the mandible in order that both sides of the fascial septum or both sides of this space can be dealt with properly. If the infection is situated above the geniohyoid muscle, it usually points under the tongue and then can be drained through the floor of the mouth, the incision passing through the mucous membrane and the genioglossus muscle. Both sides of the fascial septum should be explored.

 

 

FIG. The palatine tonsil and its relations, shown in sagittal section.

 

 

FIG. The relations of the palatine tonsil to its capsule and the surrounding structures.

 

PHARYNX TONSILS The term "tonsil" usually applies to the faucial or palatine tonsils. The tonsillar region, although anatomically located in the anterolateral pharynx and properly belonging to it, is considered as an intermediate area between the buceal cavity and the oral division of the pharynx. The tonsils are two masses of lymphoid tissue placed in the fossa tonsillaris and located on the surface at a point a little above the angle of the mandible. They lie between the palatoglossal and the palatopharyngeal arches, above the back part of the tongue and below the soft palate. Each tonsil has two surfaces (medial and lateral), two borders (anterior and posterior), and two poles (superior and inferior). The medial surface is free and can be seen through the mouth when the tongue is depressed. It faces inward and presents from 12 to 30 rounded or slitlike openings called the tonsillar crypts. Tiny plugs of food, debris or pus often fill and identify these openings. This surface is covered with mucous membrane in the form of squamous epithelium which invades the substance and lines the crypts. The lateral is the attached surface. It is covered by a fascia derived from the pharyngeal aponeurosis, which is referred to as the capsule of the tonsil. This is attached laterally by loose areolar tissue to the inner surface of the superior constrictor of the pharynx. Lateral to the superior constrictor are the ascending palatine, the pharyngeal and the tonsillar arteries; the medial pterygoid muscle is situated lateral to these. One or more veins descend over the lateral surface of the capsule. The superior constrictor separates the tonsil from the facial artery at that point where the artery begins to arch downward.

 

FIG. The blood supply of the tonsil.

 

Poles. The upper pole of the tonsil invades the lateral surface of the soft palate, and the lower is continuous with the lingual tonsil. Borders. The anterior border is in contact with the palatoglossus muscle, and the posterior with the palatopharyngeus muscle. The blood supply of the tonsil is very profuse, the main vessel being the tonsillar artery, a branch of the facial (external maxillary). This vessel enters the tonsil from its lateral aspect and near its lower pole. Other small vessels aid in the blood supply, anastomosing freely with one another. They are the ascending palatine (facial), dorsalis linguae (lingual), greater palatine (maxillary) and the ascending pharyngeal arteries.

FIG. Tonsillectomy.

 

The veins form a plexus which surrounds the capsule, pierce the superior constrictor and end in the pharyngeal plexus, which is a tributary of the internal jugular vein. The lymphatics leave the gland, pierce the superior constrictor and end in the superior deep cervical chain. One gland is situated below the posterior belly of the digastric andthe angle of the jaw. It lies on the carotid artery in the angle formed by the junction of the common facial with the internal jugular vein and has been referred to as the jugulodigastric gland (tonsillar gland of Wood). This may be enlarged not only in non-specific infections, but by the tubercle bacillus when it gains entrance by way of the tonsil. The nerve supply to the tonsil is derived from the glossopharyngeal nerve and the pharyngeal plexus.

SURGICAL CONSIDERATIONS

Tonsillectomy and Peritonsillar Abscess. When a tonsil is removed, its capsule should remain attached to it. This exposes the constrictor muscle and not the aponeurosis of the pharynx. Therefore, the capsule is removed with the tonsil because it is firmly blended with that organ. In tonsillectomy, traction on the gland pulls it forward without dragging the pharyngeal wall and the internal carotid artery. This is explained by the laxity of the tissue which exists between the gland and the superior constrictor. However, in patients who have suffered repeated attacks of quinsy, this lax tissue may be replaced by dense adhesions. Tonsillar hemorrhage following surgery is the result of bleeding from the tonsillar vessels proper, since the possibility of injuring the internal carotid is most remote and the external carotid lies still farther externally. In tonsillectomy , after proper exposure with a mouth gag and tongue depressor, a tenaculum is applied to the palatal pole, and traction made downward and medially. This maneuver makes visible the interval between the tonsil and its anterior pillar. A sharp dissector enters this space along the anterior pillar and incises just beneath the mucous membrane which covers the tonsil. Retraction of the anterior pillar with blunt dissection will expose the bluewhite capsule. If sharp dissection is preferred, the point of the scissors is applied toward the tonsil side, and an attempt is made toremain in the avascular cleavage plane. The tonsil is freed down to its lingual pole. A snare is then applied as low as possible on its base, tightened, and the base divided. A retractor is applied to the anterior pillar for the purpose of inspection, and pledgets of gauze or cotton are introduced for hemostasis by pressure. If active arterial bleeding is present, the severed artery is grasped and tied with a fine suture. In the treatment of peritonsillar abscess, an imaginary line should be drawn from the base of the uvula to the last molar of the same side. An incision is made at the junction of the anterior one third with the posterior two thirds along the arcus palatinus. This incision is spread with forceps, and the pus is allowed to flow out. Some surgeons advocate entering the tonsillar fossa with a curved sharp-pointed forceps. The approach between the tonsil and the anterior pillar seems to be an easier method of draining the supratonsillar fossa.

 

 Trigeminal Nerve.

 This is the thickest of the cranial nerves and has a wide distribution. It has a large sensory root upon which the semilunar (gasserian) ganglion is situated, the ganglion resting in a fossa on the superior surface of the petrous

 

 

FIG. The trigeminal nerve and the semilunar (gasserian) ganglion. The lateral wall of the orbit has been removed, and the maxillary sinus has been opened.

 

 

FIG. Diagram of the trigeminal nerve and the semilunar (gasserian) ganglion.

 

glion on the sensory. The nerve provides the sensory supply to the face and the anterior half of the scalp and sends motor branches to the four muscles of mastication (except the buccinator) and to four other muscles: tensor palati, tensor tympani, mylohyoid and anterior belly of the digastric. There are five ganglia on the 5th nerve: the semilunar on the nerve trunk, the ciliary on the ophthalmic division, the sphenopalatine on the maxillary division, the otic on the mandibular division, and the submaxillary (Langley's) also on the mandibular division. All these ganglia, with the exception of the semilunar, receive motor, sensory and sympathetic fibers.The semilunar (gasserian) ganglion, the sensory ganglion of the 5th nerve, occupies a space between the outer and the inner layers of dura known as the cave of Meckel (cavum trigeminale), which is in reality a diverticulum of the inner layer of dura. There are two layers of dura above and two layers below the ganglion, the two layers being fused. The foramen which transmits the middle meningeal artery is on the outer side of the ganglion and must be encountered before the ganglion is reached by the temporal route. The cavernous sinus and the internal carotid artery are found medially. The motor root makes no connections with the ganglion but passes through the foramen ovale and on the outside of the skull joins the mandibular division. Posterior to the cave the superior petrosal sinus is located as it widens to join the cavernous sinus. The sphenoparietal sinus is found anteriorly as it joins the cavernous sinus. Because of these relationships, the ganglion should be approached through the middle region of the outer aspect of the cave. The ophthalmic is the smallest division of the 5th nerve. After giving off a small twig to the dura mater, it passes forward in the lateral wall of the cavernous sinus and enters the orbit through the superior orbital fissure. In the fissure it splits into three branches: frontal, nasociliary and lacrimal. The lacrimal and the frontal branches enter the orbit above the muscles; the nasociliary passes between the two heads of the lateral rectus. The lacrimal nerve travels along the lateral part of the orbit and supplies the lacrimal gland, the conjunctiva and the skin of the upper eyelid. The frontal nerve divides into supraorbital and supratrochlear nerves that lie beneath the roof of the orbit. The supraorbital nerve reaches the scalp after passing through the supra-orbital notch (foramen) and then divides into medial and lateral branches that supply the scalp. The supratrochlear nerve runs above the pulley of the superior oblique muscle. The frontal nerve supplies the mucous membrane of the frontal sinus, the skin of the upper eyelid, the scalp and the forehead. The nasociliary nerve leaves the orbit by the anterior ethmoidal foramen and then changes its name to the anterior ethmoidal nerve. It passes over the cribriform plate of the ethmoid bone and enters the nose through the nasal slit. In the nose it gives off a medial branch to the nasal septum and a lateral branch which reaches the face after passing between the nasal bone and the upper cartilage. This nerve supplies the skin on the lower part of the nose. The branches of the nasal nerve in the orbit are the twigs to the ciliary ganglion, the ciliary nerves to the eyeball and the infratrochlear nerve. The ciliary ganglion is a small reddish body, situated between the lateral rectus and the optic nerve; it receives a sensory root from the nasociliary branch of the ophthalmic, a motor root from the lower division of the oculomotor, and a sympathetic nerve from the plexus around the internal carotid artery. It gives off from 12 to 14 short ciliary nerves which supply the muscles and the iris. The maxillary division of the trigeminal nerve resembles the ophthalmic in that it is purely sensory. It leaves the middle cranial fossa through the foramen rotundum and reaches the pterygopalatine fossa. After crossing the fossa the nerve leaves by way of the inferior orbital fissure to occupy the inferior orbital groove and canal. It appears on the face at the infra-orbital foramen as the infra-orbital nerve^ here it divides into the following terminal branches: a small meningeal branch to the dura mater; two ganglionic branches to the sphenopalatineb ganglion; zygomatic branches to the orbit through the inferior orbital fissure, which divides into the zygomaticotemporal and zygomaticofacial; posterior superior alveolar to the molar teeth; infra-orbital, which supply the three molars, the canine and the incisors; and facial, which supply the lower eyelids (palpebral), the side of the nose (nasal) and the upper lip (labial). The sphenopalatine ganglion (Meckel) is associated with the maxillary division of the 5th nerve. The sensory roots of the ganglion arise from the maxillary division of the trigeminal nerve, and the motor and the sympathetic fibers from the nerve of the pterygoid canal (Vidian). The branches of the ganglion are orbital (secretomotor fibers to the lacrimal gland), pharyngeal, nasal and palatine. The mandibular nerve is the largest division of the trigeminal. It consists of a sensory portion derived from the trigeminal ganglion, and a motor root. These two portionspass separately through the foramen ovale but rejoin immediately to form a common trunk. After giving off a meningeal branch, the nervous spinosus, which enters the cranium through the foramen spino sum, the trunk furnishes a twig to the medial pterygoid and divides into anterior and posterior divisions. The anterior division consists mainly of motor fibers and divides into deep temporal nerves, the nerves to the masseter, the lateral pterygoid nerves and the buccal nerve. The posterior division gives off the two roots of the auriculotemporal and divides into the lingual and the inferior alveolar nerves. The only motor fibers in this division are those that form the mylohyoid branch of the inferior alveolar. The anterior division has been referred to as the lingual division, and the posterior has often been called the inferior dental. As both of these divisions run downward they are concealed by the external pterygoid muscle and the ramus of the mandible and are distributed to the tongue, the gums, the lower teeth and the muscles of mastication. The lingual nerve travels forward to the anterior two thirds of the tongue, to which it is distributed. The inferior alveolar nerve, larger than the lingual, enters the mandibular canal through the mandibular foramen, passes through the ramus and the body of the mandible and distributes its branches to the lower teeth. Two ganglia—the otic and the submaxillary—are associated with the mandibular division of the 5th nerve. The otic is very small and difficult to find; it lies immediately below the foramen ovale in front of the middle meningeal artery and sends muscular branches to the tensor tympani and the tensor palati. The submaxillary (Langley's) ganglion is also associated with the mandibular division, lying on the outer surface of the hyoglossus muscle and joining the lingual nerve. Although the 5th nerve is mainly sensory, it may be tested by utilizing its motor branches to the masseter muscle. When the nerve is involved the masseter will not protrude on the affected side if the patient clenches his teeth.

 Facial Nerve. This nerve is seen when the cerebellum is removed. It is the motor nerve to the face and contains no cutaneous branches. Leaving the brain at the lower border of the pons and accompanying the auditory 8th nerve into the internal auditory meatus, it passes through the temporal bone and leaves the skull through the stylomastoid foramen. In the temporal bone it gives off the great superficial petrosal nerve, which sends sensory fibers to the mucous membrane of the soft palate and secretory fibers to the mucous glands; the nerve to the stapedius muscle; and the chorda tympani, which passes through the tympanic cavity, joins the lingual nerve and thus supplies taste and sensation fibers to the anterior two thirds of the tongue and secretory fibers to the submaxillary and sublingual glands. At the exit from the stylomastoid foramen the facial nerve gives off the posterior auricular nerve and a branch which divides into two twigs supplying the stylohyoid muscle and the posterior belly of the digastric. The posterior auricular nerve ascends behind the ear and supplies the posterior and the superior auricular muscles and the occipital belly of the occipitofrontalis. Having given off its branches in the temporal bone and at the exit from the stylomastoid foramen, the facial nerve supplies its terminal branches to the face. Here it divides into two main divisions: a temporofacial and a cervicofacial. A controversy exists at present as to whether the facial nerve runs through the parotid gland or whether it passes around the isthmus of the gland, thus being "sandwiched" between the so-called superficial and deep lobes of the gland.

 

FIG. The facial nerve. It divides into two divisions: the temporofacial and the cervicofacial. These give rise to the 5 terminal branches which form the pes anserinus (goose's foot).

 

The two divisions break up into a nerve plexus which has been called the pes anserinus (goose's foot). These terminal nerves forming the plexus emerge at the anterior border of the parotid gland and radiate over the side of the face in a fanlike manner. The temporofacial division gives rise to 2 terminal branches: temporal and zygomatic. A temporal branch appears at the upper border of the gland and supplies the frontalis muscle and the facial muscles which are situated above the zygoma. The zygomatic branches are divided into a smaller upper branch, which passes forward from the upper anterior border of the parotid to the zygomatic bone and supplies the adjoining facial muscle, and a lower zygomatic branch, which appears at the anterior border of the gland and runs with the transverse facial vessels to the muscles of the upper lip and the nose. The cervicofacial division gives rise to the buccal, the mandibular and the cervical branches. The buccal branch appears at the anterior border of the gland and supplies the buccinator and the orbicularis oris muscles. The mandibular branch supplies the

lower lip and the chin. The cervical branch appears at the lower border of the gland and supplies the platysma and the depressors of the lower lip. Intracranial lesions of the facial nerve are characterized by involvement of only the lower half of the face; cranial lesions may result from middle-ear diseases or fractures of the face or the skull. Extracranial lesions result in facial paralysis, as seen in Bell's palsy, in which condition the involved side of the face is flat and expressionless; the patient is unable  to whistle, blow out his cheeks, wrinkle his forehead or show his teeth. In its course the facial nerve makes connections with the auriculotemporal and the great auricular nerves.

PARANASAL SINUSES The paranasal sinuses are irregular air spaces or diverticula originating from buds of mucous membrane that sprout from the nasal cavities and grow into the diploic layer of certain bones. Each sinus takes its name from the bone in which it is situated: maxillary (antrum of Highmore), frontal, ethmoid and sphenoid. These sinuses are enclosed in compact bone. They communicate with the nasal cavities with which their mucous membranes are continuous and are filled with air. They communicate with the nasal cavities by means of narrow orifices that may become occluded because of congested mucous membrane. Like the mucous lining of the nose, the membrane lining the sinuses is covered with ciliated epithelium. The anatomy of the paranasal sinuses is somewhat inconstant, since there is no definite constancy in their size, shape and type. Under normal conditions during respiration there is an interchange of air between them.

MAXILLARY SINUS (ANTRUM OF HIGHMORE) This maxillary sinus is the largest of the paranasal sinuses and is the first to appear. Although it begins to develop about the 4th month of intra-uterine life, it continues to grow in the adult, acquiring its maximum development in the 2nd or the 3rd decade. The sinus varies considerably in size in different individuals, but the following have been given as the average dimensions: anteroposterior, 1 and 1/4 inches; transverse, 1 inch; vertical, 1 and ½ inches. Situated in the interior of the superior maxilla, the base of this  pyramidal cavity is formed by the lateral wall of the nasal cavity, and the apex extends to the zygomatic process; its roof is formed by the orbital wall, which is frequently ridged by the infra-orbital canal, and its floor by the alveolar process.

 

 

FIG. Paranasal sinuses: (A) surface projection of the sinuses, (B) sagittal section (semidiagrammatic), showing the 4 paranasal sinuses.

 

 

FIG. Normal x-ray appearance of the paranasal sinuses in a lateral projection: (1) frontal sinuses, (2) ethmoid cells, (3) sphenoid sinus, (4) maxillary sinuses, (5) anterior clinoid processes of the sella turcica, (6) posterior clinoid processes of the sella turcica, (7) sella turcica.

 

In front the pyramid is bounded by the facial surface of the superior maxilla and behind by the zygomatic surface of the same bone. This sinus lies lateral to the lower half of the nasal cavity in front of the pterygopalatine and the infratemporal fossae, below the orbit and above the molar teeth. The infra-orbital nerves and vessels lie in the roof of the sinus, and their branches to the incisor, the canine and the premolar teeth descend in the anterolateral wall. This nerve produces infra-orbital facial pain when the maxillary sinus is diseased.

 

 

FIG. X-ray projection for the upper half of the orbit, showing an effusion in the right maxillary and the frontal sinuses. These should be compared with the normal sinuses on the left side: (1) right frontal sinus, obliterated by effusion; (2) left frontal sinus, normal appearance; (3) roof of the orbit; (4) lesser wing of the sphenoid; (5) sphenoidal fissure; (6) greater wing of the sphenoid; (7) right maxillary sinus, obliterated by effusion; (8) left maxillary sinus, normal appearance; (9) zygoma.

 

The floor formed by the alveolar margin is about 1/2 inch below the nose, and in it are seen elevations produced by the roots of some of the upper teeth, the most usual being the 1st and the 2nd molars. It is possible that all true maxillary teeth (canine to the "wisdom") may be in relation to it. At times the roots actually project into the sinus, but as a rule they produce a bulge into the floor and are separated from the cavity by a thin layer of spongy bone. This relationship between teeth and sinus explains the production of maxillary disease by infected teeth and also the establishment of drainage for an empyema of the sinus by removal of one of these teeth. The floor of the sinus is not smooth, since it presents incomplete septa that form pockets in which inflammatory products may stagnate. Such pockets may be inaccessible to treatment and must be handled individually. The nerves and the vessels to the molar teeth descend in the lower part of the posterior wall of the antrum. The sinus drains into the infundibulum of the middle meatus of the nose by means of a maxillary ostium; this opening varies from a tiny slit to a complete replacement of the floor of the infundibulum. The maxillary sinus is more frequently the site of disease than are any of the other accessory sinuses. Infection may take place through the upper molar alveoli and by way of the nose. Tumors of the antrum are not too uncommon; hence, knowledge of the surrounding anatomy is important. A malignant tumor may grow rapidly and by pressure upward can encroach upon the eyeball; growth downward may involve the palate and loosen the teeth; inward extension would obstruct the nostril, and backward involvement would invade the pharynx. Such growths should be treated by excision of the superior maxilla.

Surgery. Acute nasal infections that are severe or have a tendency to persist may extend to the maxillary sinus as well as to any of the other sinuses. Carious teeth projecting into the sinus cavity may also be the cause of such infections, or extension from adjacent sinuses (frontal, sphenoid and ethmoid) can be the inciting agent. If pus is present in the maxillary sinus, it may be visible at the middle meatus. Of all the nasal sinuses, the maxillary is the easiest to irrigate. This can be done by one of four methods: by entering the natural opening (ostium) or by perforating the nasoantral wall directly beneath the inferior turbinate. Since the natural opening is placed at too high a level for pus to escape, it may remain stagnant. Therefore, it becomes necessary to explore or drain the antrum via another route. A needle is introduced through the nostril and is passed outward and backward. It pierces the bone under cover of the inferior turbinate (inferior nasal concha) and enters the sinus at a much lower level than the natural orifice of the cavity. The sinus may also be entered through the region of a tooth which is at fault after that tooth has been extracted and a hole drilled upward through its socket and into the sinus. This dental approach was used for many years in empyema of the antrum, but unfortunately infections recurred from the mouth. This, plus insufficient drainage, has resulted in its being discarded by some authorities. Another approach to the maxillary sinus —by many believed to be the best—is that which passes through the outer oral wall. The head is turned to the sound side, and the lip is retracted upward and backward. An incision is made over the roots of the teeth from the canine to the 2nd molar, and the periosteum is divided in the same line and separated from the bone. The facial wall of the antrum is opened by means of a small chisel, and the interior is curetted. Drainage into the nares may be instituted by removing the anterior part of the inferior turbinate.

FRONTAL SINUSES The frontal sinuses, bilaterally placed cavities of variable extent situated anteriorly between the two plates of the frontal bone, have been considered as extensions of the anterior ethmoid cells. The anterior wall of each sinus is responsible for the prominence of the forehead, which is situated above the eyebrow. Although not present at birth and not usually recognizable until the 7th year of life, this sinus may appear as early as the age of 2 years. It is separated from its fellow by a complete bony septum which is often deviated to one side so that one sinus is larger. The septum thins as the sinuses grow and at times may even disappear by absorption. This sinus is about 1 inch in both height and width but may be much wider and considerably higher and has been known to extend backward between the two tables of the roof of the orbit. In its peripheral parts there are small partitions that form loculae and produce an irregular outline. The sinus presents a posterosuperior wall, an anterior wall and a floor. The posterosuperior wall is thin, contains no diploe and separates the sinus from the meninges and the frontal convolutions of the brain. The anterior wall looks onto the forehead and contains diploe. Because of the presence of these diploe, infectious processes involving the bone (osteomyelitis) spread more readily in this wall than in the posterior. The floor in the frontal sinus separates it from the orbit, the nose and the anterior ethmoid sinuses. The sinus opens into the nose via the infundibulum, a narrow canal that passes between the anterior ethmoid air cells. The sinus then opens into the hiatus semilunaris. Due to the close relationship of sinuses and their openings, an infection in one sinus can, and usually does, spread to another. Therefore, it is not uncommon for an opening of the maxillary sinus to receive pus from the frontal and the anterior ethmoid cells as it travels along the hiatus semilunaris.

 

 

FIG. Surgery of the maxillary sinus: (A) via the natural opening, (B) through the naso-antral wall, (C) the outer oral wall approach, (D) dental approaches.

 

The maxillary sinus thus becomes involved and produces its usual symptoms, which may divert attention from the true source of the infection (frontal or anterior ethmoid sinus disease). A fracture over the frontal sinus can be depressed without injuring the cranial contents, but such fracture may be associated with emphysema of the surrounding tissues due to communication with the nose. Inflammation of the mucous lining of the frontal sinus may be secondary to an infection in the nose; conversely, when pus forms within this sinus, it may drain into the nasal fossa. If the communication with the nose is blocked because of swelling of the lining membrane, it may give rise to serious complications by destroying the internal table and infecting the cranial contents; it may even perforate the wall of the orbit and produce serious eye complications. An early diagnosis of the presence of pus in the frontal sinus calls for opening into the sinus by trephining over the supra-orbital margin.

Extranasal and Intranasal Approaches. Interference with the normal ventilation or drainage of the frontal sinus is usually associated with marked edema in the region of the middle meatus, and the middle turbinate becomes tightly compressed against the lateral wall.

 

 

FIG. Extranasal approach to a diseased frontal sinus.

 

A deviation of the nasal septum also aggravates the condition, and if the inflammatory process becomes purulent, empyema of the sinus results. When the frontal duct is open, pus passing along the semilunar hiatus may involve the opening of the maxillary sinus and produce a sinusitis here. Since the anterior ethmoidal cells open with the frontal duct into the infundibulum of the semilunar hiatus, these cells too may become involved in frontal sinus disease. Osteomyelitis or abscess of the frontal bone may result and can terminate in meningitis. An intranasal operation for sinus disease is utilized by some and is described under surgery of the ethmoid cells.

The extranasal or external approach is usually performed in the following way the eyebrow is shaved, and an incision is made, beginning at the temporal end, extending to the middle of the root of the nose and then curving downward to the base of the nasal bone. The soft parts are freed from the bone, and then two incisions are made in the periosteum. The first is placed just above and parallel with the supra-orbital margin; the second passes over the frontal process of the maxillary bone. These two incisions do not meet. The frontal sinus is opened, thoroughly curetted, and its floor removed. The frontal process of the frontal bone and as much of the lacrimal bone as is necessary are removed through the second incision. This gives access to the ethmoid cells, and the ethmoid sinus is curetted. The operation also permits access to the anterior wall of the sphenoid sinus. Drainage is instituted by means of a tube that is placed in the upper wound, carried under the bridge of the bone through the nose and out at the nostril.

SPHENOID SINUS The sphenoid sinus, a large cavity situated in the body of the sphenoid bone, is divided into right and left halves by a complete bony septum usually bent to one side. Each half has been referred to as a sphenoid sinus, and each has its own opening. The sinus may be limited to the anterior part of the bone, but usually occupies the whole of its body, extending into the wings of the sphenoid, the pterygoid process and even into the basilar process of the occipital bone. Formation of the sinus begins in the 5th month of intrauterine life as a recess of the nasal cavity but does not extend into the body of the sphenoid until the 7th year. Both sinuses have important relationships above, below, in front and laterally. Above the sphenoid sinus, the pituitary body and the optic nerve are found, the nerve at times forming a ridge inside the sinus. This close relationship causes the optic nerve to be involved in sphenoid sinusitis, giving rise to sudden loss of vision (retrobulbar neuritis). The sinus is bounded below by the nose. In front, the wall of the sinus separates it from the ethmoid air cells, and laterally the cavernous sinuses containing the internal carotid artery and the 6th nerve are located. The abducens, the oculomotor and the trochlear nerves, and the ophthalmic and the maxillary divisions of the trigeminal nerve may be involved in disease of the sphenoid sinus, which is considered a "danger spot" in the skull because of these important surrounding structures. Each half of the sinus has an orifice of its own that opens into the highest meatus, the spheno-ethmoid recess.

Surgery. The sphenoid sinuses may be drained by an external route as described in operations involving the frontal sinuses, or through a nasal route. In the nasal route the posterior half of the middle turbinate is removed, and a small hook or curette is introduced upon the anterior superior wall of the nasal cavity. The point of this curette is carried downward and then turned forward and outward toward the eye of the involved side. It is firmly pressed into the posterior ethmoid labyrinth and then drawn forward and downward. The posterior wall of the labyrinth is entirely broken down. The sphenoid sinus is located, entered, and  its anterior wall removed.

ETHMOID SINUSES (CELLS) There are from 8 to 10 very thin-walled intercommunicating cavities occupying the greater part of the ethmoid labyrinth and known as the ethmoid sinuses. The boundaries of these sinuses are completed by the frontal, the palatine, the sphenoid bones and the superior maxilla. They have been divided arbitrarily into  three sets: anterior, middle and posterior. The anterior ethmoid sinuses open into the middle meatus on the floor of the hiatus semilunaris; the middle ethmoid sinuses open into the middle meatus on the surface of the bulla ethmoidalis; the posterior, into the superior meatus. Above the ethmoid sinuses are the meninges and the frontal convolutions in the anterior cranial fossa; in the front is the frontal sinus; behind is the sphenoid; below, the nose; and laterally, the orbit. The ethmoid cells in each labyrinth may vary from 4 large cells to 17 small ones, the average  number being 9. These spaces are separated from their surrounding structures by extremely thin plates of bone (lamina papyracea); because of this, infection may spread to the surrounding parts quite readily. This explains why ethmoiditis is the most common cause of orbital cellulitis. The relations of the ethmoid air sinuses to the cranial cavity are more extensive than those of the frontal and the sphenoid; hence, meningitis, subdural abscess, cerebral abscess and sinus thrombosis may complicate ethmoiditis. It should be recalled that the frontal sinus has been considered as one of the anterior ethmoid cells.

Nasal Approach. Acute inflammation of the ethmoid cells at times is associated with acute rhinitis (common cold) and diseases of the frontal and the maxillary sinuses. The diseased ethmoid sinus can be opened and drained externally by procedures that have been described for frontal sinus drainage, but more frequently the nasal route is used. A curette is introduced into the nasal cavity through the vestibule and carried to the anterior attachment of the middle turbinate. This is pressed firmly downward from the orbit and removes the anterior aspect of the turbinate. The curette is carried through the turbinate, the hiatus semilunaris removed, and entrance gained to the anterior.

 

FIG. Surgery of the sphenoid and the ethmoid sinuses: (A) nasal approach to the ethmoid sinuses (cells); (B) nasal approach to the sphenoid sinus.

 

Facial and Head Nerve Blocks

Surgery of the head is rarely performed with regional anesthesia alone, but facility with blockade of the nerves of the head is useful in many diagnostic and therapeutic pain procedures.

Sensory fibers to the posterior scalp arise from the upper cervical roots and course upward over the occiput as the greater and lesser occipital nerves. These nerves can be blocked superficially on the posterior scalp or more centrally by blockade of the deep cervical plexus. The anterior portion of the scalp and the face are innervated by the branches of the trigeminal nerve. The three main branches of this cranial nerve are the ophthalmic, maxillary, and mandibular. These produce (respectively) the three main terminal sensory nerves of the face: the supraorbital, the infraorbital, and the mental. These nerves can be blocked at their superficial foramina or more centrally just beyond their trifurcation and exit from the skull. The trigeminal nerve arises from the base of the pons and sends its sensory fibers to the large gasserian (or semilunar) ganglion on the superior margin of the petrous bone just above the foramen ovale. Direct alcohol neurolysis of this ganglion for total trigeminal ablation has been practiced in the past. The risks of intracranial spread of the neurolytic solution are significant. Radiofrequency ablation by a neurosurgeon using fluoroscopic guidance is more com­mon today. The three branches of the ganglion depart the skull through separate exits. The uppermost ophthalmic nerve enters the orbit through the sphenoidal fissure. Its main branch, the frontal nerve, bifurcates into the supraorbital and supratrochlear nerves. The former exits the superior border of the orbit at the supraorbital notch, while the latter departs the orbit more medially. The middle branch of the trigeminal, the maxillary nerve, is also purely sensory, but it is somewhat larger than the ophthalmic nerve. It exits the skull through the foramen rotundum and crosses the sphenomaxillary fossa medial to the lateral pterygoid plate to reenter the bone of the floor of the orbit in the infraorbital canal. In the fossa, it gives off the sphenopalatine branches medially to the pharynx and the orbital and posterior dental branches.

Occipital Nerve Block

The greater and lesser branches of the occipital nerve emerge from under the muscles at the level of the nuchal ridge on the posterior scalp. They can be easily blocked by a subcutaneous ridge of anesthetic solution.

 

The anterior dental branches arise from the main trunk while in the canal. The infraorbital nerve that finally emerges from the infraorbital foramen just below the eye branches into the palpebral, nasal, and labial nerves. The mandibular branch is the largest branch of the ganglion, and it exits the skull through the foramen ovale. It lies just posterior to the lateral pterygoid plate of the sphenoid bone. It contains the only motor fibers of the trigeminal, the branches to the muscles of mastication. These nerves are carried by an anterior branch that separates from the nerve just after its exit from its cranial foramen. The poste­rior branch gives off an early auriculotemporal nerve that provides sensory innervation to the auricular and temporal regions of the lateral scalp. The main trunk continues as the inferior alveolar nerve to the lower jaw. Its terminal branch is the mental nerve, which exits the mental foramen to supply the lower lip and jaw. All three of the main trunks lie deep and are well protected by the skull, the mandible, and the zygomatic arch. The terminal branches are superficial, and their foramina are relatively easily identified.

 

Trigeminal Nerve, Sagittal View

Each of the three main branches of the trigeminal nerve exits the skull through its own foramen and provides sensory innervation of the face and jaw.

 

Conveniently, the three external foramina lie in the same sagittal plane.

Indications Surgical indications for anesthesia of any of these pathways are rare. Performance of cranial burr holes on the debilitated patient can be done with occipital nerve blocks and field infiltration. Generally, anesthesia of the branches of the trigeminal nerve is used only in attempts to diagnose and treat pain complaints. Occasionally, a patient with tic douloureux involving a branch of the trigeminal nerve will respond to block of the nerve with local anesthetic or a neurolytic agent. Incapacitating pain of malignancy also can be relieved by a neurolytic block, although the advent of radiation, chemother-

 

Terminal Branches of the Trigeminal Nerve

Each of the three terminal branches (the supraorbital, infraorbital, and mental) exits its respective bony canal in the same sagittal plane, approximately 2.5 cm from the midline. The infraorbital canal is'angled slightly cephalad, while the mental canal can be entered if the needle is directed medial and slightly caudad.

 

apy, and radiofrequency ablation techniques has made this requirement rare. Occipital nerve block is occasionally useful in relieving some headaches, but it is rarely an adequate long-term therapy.

Drugs. Any of the local anesthetics in lower concentrations are appropriate for facial or head blocks. Bupivacaine 0.25% is probably best for diagnostic blocks, since its longer duration may help differentiate some physiologic pain complaints from those of psychological origin and may help the patient who is considering a neurolytic procedure. Alcohol is the preferred neurolytic agent for facial blocks, but this therapy is usually reserved for patients who are not candidates for radiofrequency ablation.

Occipital Nerve Block

The greater and lesser occipital nerves emerge from under the muscles of the neck on each side to become superficial at the level of the nuchal line, the prominent ridge of bone extending from the mastoid to the external occipital protuberance.

1.      The patient is asked to sit with the head flexed toward the chest.

2.      The external occipital protuberance is palpated, and an "X" is marked on the involved side at this level just lateral to the insertion of the erector muscles of the neck (usually 2.5 cm laterally from the midline).

3.  After wiping the skin with an alcohol swab, a 23-gauge needle is inserted at the "X" and is advanced gently until it contacts the bone. It is withdrawn slightly, and a ridge of 3 cc of local anesthetic is injected under the mark and on either side of it.

4.      If lesser occipital nerve block is also desired, the needle is then angled anteriorly and laterally along the skull, and the subcutaneous injection is extended from this area forward to the area of the mastoid process. A total of 6 to 8 cc will usually suffice.

5.      Care is taken not to advance the needle under the angle of the occiput toward the foramen magnum.

6.      If anesthesia of the entire scalp is desired, the subcutaneous wheal is carried around the entire circumference of the scalp, but it is angled so that it crosses above the ear on each side and extends at this same level anteriorly.

Facial Anesthesia

The three terminal sensory branches of the trigeminal nerve can be blocked at their respective foramina. For all three blocks, the patient lies supine with the head slightly elevated.

1.  For the supraorbital nerve, the supraorbital notch is palpated along the superomedial rim of the orbit, usually 2.5 cm from the midline. Paresthesias should be elicited in the notch if a neurolytic agent is to be injected, but, for simple anesthesia, 2 cc can be injected in the area. For medial (supratrochlear) anesthesia, a line of superfiial infiltration at the level of the orbital rim should be continued medially to cross the midline. The infraorbital nerve exits its foramen just below the inferior orbital rim and at the same distance from the midline as the supraorbital notch (approximately 2 cm from the lateral border of the nose). The foramen can be palpated directly or discovered with a gentle, exploring 23-gauge needle. The needle should be introduced through a skin wheal 0.5 cm below the anticipated level of the opening, since the canal angles cephalad from this point. Once the foramen is identified, 2 cc of local anesthetic is injected at the orifice. If a neurolytic agent is used, paresthesias are necessary and 1 cc alcohol is sufficient.

3. The mental nerve canal of the mandible also lies 2.5 cm from the midline, usually about midway between the upper and lower borders of the mandible. Again, the opening usually can be palpated directly, but it can be marked with an approximate "X" and explored for gently with a 23-gauge needle. The canal angles medially and inferiorly such that needle insertion should not be perpendicular to its opening but should start 0.5 cm above and 0.5 cm lateral to the orifice. Injection of 2 cc of anesthetic in the foramen will anesthetize the nerve. If a neurolytic agent is used, paresthesias are again necessary and smaller quantities are sufficient. In older patients, resorption of the mandibular bone will cause the foramen to lie relatively more superiorly along the mandible.

Maxillary Nerve Block

When tic douloureux or neuralgia of the middle division (presenting as both facial and upper dental pain) requires more proximal block, the maxillary nerve is blocked in the sphenopalatine fossa.

1.      The patient lies supine with the head turned slightly away from the side to be blocked.

2.      The zygomatic arch is identified and marked. The patient is then asked to open and close the mouth slowly while an index finger explores the upper border of the mandible. The mandibular notch will be felt moving up and down anterior to the temporomandibular joint at the midpoint of the zygoma. An "X" is marked over the notch at its deepest point.

3.      After aseptic preparation, a skin wheal is raised at the "X."

4.      A 7.5-cm needle is introduced through the "X" and directed 45 degrees cephalad and slightly anterior, aiming at the imagined position of the back of the globe of the eye itself.

5.      When the pterygoid plate is contacted, the needle is withdrawn and redirected slightly anteriorly. When the needle succeeds in passing anterior to the pterygoid plate, the nerve lies about 1 cm deeper. Paresthesias to the nose or upper teeth confirm the appropriate location.

6.      If paresthesias are not obtained, anesthesia can be achieved by injecting 5 cc into the fossa 1 cm deep to the plate. For a neurolytic block, a paresthesia is essential, and 1 cc alcohol will suffice. Alcohol injection is painful, and the head must be secured by an assistant during the injection to prevent movement. Sedation or analgesia is appropriate after localizing paresthesias are obtained.

 

 

 

Lateral View of Major Branches of the Trigeminal Nerve

The maxillary and mandibular branches emerge from the skull medial to the lateral pterygoid plate, which serves as the landmark for their identification. A needle introduced onto the plate can be advanced anterior for the maxillary nerve and posterior for the mandibular nerve.

Mandibular Nerve Block

The mandibular nerve also can be blocked for neuralgia, tic problems, or cancer pain, but anesthesia here may induce some weakness of the muscles of mastication.

1.      The position and superficial landmarks are the same as for the maxillary nerve (steps 1 to 3).

2.  A 5-cm needle is introduced through the skin wheal and directed medially and slightly posteriorly. Less cephalad angulation is required. The needle will usually be perpendicular to the skin in all planes.

Lateral pterygoid plate

 

Lateral Approach to the Maxillary Nerve

The needle is introduced through the skin just over the notch of the mandible and is directed anterior and cephalad to identify the pterygoid plate. As the needle is advanced anteriorly off the plate, the maxillary nerve is encountered before it reenters the skull in the infraorbital canal in the base of the orbit.

 

3.  The needle is advanced until bone is contacted. This will be the posterior border of the lateral pterygoid plate. The needle is redirected posteriorly off the plate and should contact the nerve 0.5 to 1.0 cm deep to this point.

4.  Paresthesias of the jaw or teeth confirm identification of the nerve. If not obtained, they may be sought by gently exploring cephalad and caudad. In the absence of paresthesias, 5 to 10 cc of solution may be injected 0.5 cm deep to the posterior border of the plate with reasonable confidence that it will produce anesthesia. Careful aspiration and test doses are required because of the proximity of the middle meningeal artery.

Lateral Approach to the Mandibular Nerve

The needle is introduced the same as for maxillary nerve block, but it is directed posteriorly. After contacting the pterygoid plate, it is directed further posteriorly until it passes behind the plate, where it should encounter the nerve.

 

5. If alcohol is to be used, 1 cc will suffice, but paresthesias are essential. Again, injection is painful, and the same precautions should be employed as with the maxillary block.

 

 

RECOMMENDED LITERATURE:

1.     Mark W. Wolcott. Ambulatory Surgery End The Basic Of Emergency Surgical Care.-Philadelphia:J.B.Lippincott Company,2001.-752p.

2.     Michael F. Mulroy.Regional Anesthesia /The Virginia Mason Medical Center/ Little, Brown and Company,1998.-327p.

3.     Richard M. Stilman,M.D.,E.A.C.S. General Surgery /Review And Assessment/ Appleton Century Crofts, 1999.-328p.

4.     Kent M. Van De Graff, Stuart Ira Fox, Karen M. Lafleur. Synopsis of Human Anatomy and Physiology /WCB McGraw-Hill/, 2004.-675p.

5.     John J. Jacobs. Shearer’s Manual Of Human Dissection /McGraw-Hill Information Services Company, 1998.-300p.

6.     Branislav Vidic,S.D. Manual Of Dissection /The C.V.Mosby Company/ St.Louis Toronto Princeton, .1997.-120p.

7.     Philip Thorek. Anatomy In Surgery /J.B.Lippincott Company/,1996.-935p.