Employment 2. Topographical
Anatomy and Operative Surgery of Cranial Cavity. Topographical Anatomy of
the Face. Operative Interventions in Case of Purulent
Facial Processes.
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
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
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.
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.
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
FIG. Division of the sensory root of the trigeminal nerve.
of
the palpebral fascia. 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
FIG.The parotid
gland: (A) superficial relations, (B) the most common pattern formed by the
fine branches of the facial nerve.
occipitofrontalis.
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
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.
superficially.
It is triangular in shape, its base corresponding to its insertion in the
neighbourhood of the angle of the mouth.
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 the gland could be joined at various
locations. 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 IVi inches long and Vs 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
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
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.
TEMPORAL AND INFRATEMPORAL REGIONS MUSCLES OF
MASTICATION
The muscles of mastication include the temporal,
the masseter, the external and the internal pterygoids, the mylohyoid and the
anterior belly of the digastric. All of these are supplied by the trigeminal
nerve (mandibular branch). Since they do not appear over the same region of the
face, only those concerned with the temporal and the infratemporal regions will
be discussed here. Temporal Fascia. This
strong aponeurotic layer covers the upper aspect of the temporal muscle,
attaches above to the superior temporal line and splits below into two layers
attached to the lateral and the medial margins of the upper border of the
zygoma. The space thus formed is occupied by fatty tissue and some small blood
vessels. Temporal Muscle. This muscle
arises from the whole of the temporal fossa (frontal, parietal, squamous
portion of the temporal and greater wing of the sphenoid bones), and its fibers
converge on a gap that exists between the zygoma and the side of the skull. The
fibers pass downward deep to the zygomatic arch, then beneath the masseter, and
become inserted into the margins of the deep surface of the coronoid process.
Some anterior fibers descend beyond the coronoid to reach the anterior border
of the ramus of the mandible. A true view of the muscle can be obtained only if
the temporal fascia is removed and if the zygoma is divided and turned downward
together with the masseter muscle. The muscle is a powerful elevator of the
mandible, and its posterior fibers act as a retractor of the same bone. Nowhere
else in the body is a group of muscles opposed by so weak a group of opponents
as in this region. The temporal, the masseter and the
internal pterygoid muscles produce the great biting and grinding power, but
their opponents which depress the mandible (external
pterygoid, digastric, mylohyoid and geniohyoid) are able to afford only weak
resistance. Therefore, when a state of spasm is produced, the stronger group
prevails. Should this spasm be clonic, a chattering of the teeth occurs, but if
the spasm is tonic, the mouth is rigidly closed, and the condition known as
trismus or lockjaw results. This locking of the jaw is a frequent symptom of
tetanus but is also found in any condition that might produce an irritation of
the mandibular branch of the trigeminal nerve, as is sometimes seen in caries
of the lower teeth or during the cutting of a lower wisdom tooth. Masseter Muscle. This muscle is held firmly by
the masseter fascia, which binds it to the margins of the ramus and the body of
the mandible; the muscle covers nearly the entire lateral surface of the ramus
of the mandible. An expansion of the fascia overlies the fat pad of the cheek
and holds it against the buccinator muscle. The parotid duct lies within the
fascia and is protected by it. The muscle arises by two closely associated
heads: a superficial and a deep, which arise from the surface of the zygomatic
arch. It is inserted into the lateral surface of the ramus and the coronoid
process of the mandible. The muscle raises and protrudes the mandible, and its
fibers may be felt well if the jaws are clenched firmly. The transverse facial
vessels, the parotid duct and branches of the facial nerve all lie on its
lateral surface, and the parotid gland overlaps it posteriorly. The muscle does
not cover the head and the neck of the mandible. Pterygoid
Muscles. These muscles lie on a deeper plane and are almost
completely hidden by the ramus of the mandible. Only a small part of the
external pterygoid can be seen through the mandibular notch. Many authors
prefer to consider the internal {medial) pterygoid muscle as being
associated with the masseter, and these two muscles
have been likened to the two bellies of the digastric. The fibers of the
internal pterygoid originate from the medial surface of the lateral pterygoid
lamina and by a small slip from the tuberosity of the maxilla. They pass
downward and backward and insert into the medial surface of the ramus of the
mandible from the mandibular foramen to the angle. The muscle elevates the
mandible, protrudes it and pulls it to the opposite side. Superficial to this
muscle is the ramus of the mandible, the external pterygoid, the lingual and
the inferior dental nerves, the maxillary and the inferior dental vessels and
the sphenomandibular ligament. Deep to it are the tensor palati and the levator
palati, the superior constrictor of the pharynx and the eustachian (auditory)
tube. The external (lateral) pterygoid muscle originates by two heads:
the lower from the lateral surface of the lateral pterygoid lamina, and the
upper from the undersurface of the great wing of the sphenoid. The fibers are
directed backward and become inserted in the digital fossa on the front of the
neck of the mandible and to the capsule and the disk of the mandibular joint.
In this way its contraction opens the mouth by sliding the condyle forward and
protruding the jaw. One muscle acting alone pulls the chin over the opposite
side. The internal maxillary artery crosses the lower head of the muscle
obliquely and, as a rule, runs superficial to it. Buccinator.
This forms the muscle layer of the cheek and is discussed here for the sake
of completion. It arises from the outer alveolar margins of both the upper and
the lower jaws in the region of the molar teeth and passes to the angle of the
mouth, where it blends with the orbicularis oris. The middle fibers decussate
at the angle of the mouth, so that the uppermost fibers pass to the lower lip
and vice versa. It is supplied by the buccal branches of the facial nerve. By
its action of retracting the angle of the mouth and flattening the cheek, it
compresses the cheek so that during mastication food is pushed beneath the
molar teeth. Compression of the cheek against the gums prevents masticated food
from becoming lodged there. In paralysis of the facial nerve it becomes
necessary for the patient constantly to dislodge the food with his finger. This
muscle also aids in the act of blowing and whistling. Its superficial surface
is covered with buccal pharyngeal fascia, and its deep surface is lined with
the mucous membrane of the cheek. Posteriorly, it is covered by the buccal fat
pad, which separates it from the masseter and the temporal muscles, anteriorly,
by the superficial fascia, which contains the facial artery, the anterior
facial vein, the buccal nerve and artery and the buccal branches of the facial
nerve. The muscle is pierced by the parotid duct and twigs from the buccal
nerve.
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 (p. 60). 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. 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
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.
pterygoids
of opposite sides acting alternately. 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 the internal pterygoid, the temporal
and the masseter muscles and is thereby spastically fixed in place.
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.
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
FIG. The palatine tonsil and its relations, shown in sagittal section.
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.
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. 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. 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.
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 (
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 (
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. In my experience
at both the dissecting and the operating tables,
I usually have found that the nerve passes
through the gland. This is considered more fully on page 120 where the parotid
gland is discussed. 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,
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.
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. 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
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.
produces infra-orbital facial pain when the
maxillary sinus is diseased. 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
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.
to receive pus from the frontal and the anterior
ethmoid cells as it travels along the hiatus semilunaris. 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 lat-
FIG.
Extranasal approach to a diseased frontal sinus.
eral wall. 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
Tympanic
(Mastoid) Antrum. The tympanic
antrum is a large recess situated in the posterior part of the petrous
portion of the temporal bone. It is about the size of a small pea and is really a large mastoid air
cell. The aditus (aditus ad antrum), an oval slit with its long axis
nearly vertical and measuring about a YA inch, connects the epitympanic
recess with the antrum. Any obstruction of this narrow aperture favors stasis
and retention of inflammatory exudates that may find their way to the mastoid
cells. Both the aditus and the antrum lie just below the tegmen tympani. Since
the aditus opens close to the roof of the antrum, it is not in an efficient
place to drain that cavity. The tympanic antrum is relatively larger and more
superficial in the child than in the adult. Superiorly, it has a roof
that is the backward continuation of the tegmen tympani and is, therefore, in
close relationship to the middle cranial fossa and the temporal lobe of the
brain. Involvement of this wall may cause a subtemporal abscess. Its anterior
wall has in its upper part an opening which communicates with the
epitympanic recess; this opening has been referred to above as the aditus. Its posterior
wall opens into mastoid air cells and separates the antrum from the sigmoid
(transverse) sinus and the cerebellar hemisphere. The lateral wall is
formed by the squamous part of the temporal bone, is about Vz inch thick
in the adult, is the wall of surgical approach and projects laterally in that
part of the temporal bone that is covered by the auricle. Above the promontory
and even above the fenestra vestibuli is found the canal for the facial
nerve (aqueduct of Fallopius). This canal contains the facial nerve as it
travels in its intrapetrous portion. It also forms a ridge, the wall of which
is so extremely thin that the nerve may be seen through it. Above the fenestra
ovalis the facial canal, together with the external semicircular canal, form
the inner boundary of the aditus. This is an important relationship and should
be kept in mind in any operative procedure in this region. At the medial wall
of the aditus the facial canal curves downward and opens on the inferior
surface of the temporal bone at the stylomastoid foramen. The chorda tympani
nerve passes forward etween the handle of the malleus and the long process
of the incus, reaching a small opening in front of the upper part of the
tympanic ring. The mastoid process does not exist at birth but begins
its development at the end of the first year. As it grows, its diploe is
gradually replaced by air cells. The mastoid cells usually occupy the
whole of the mastoid process, which has a very thin coating of compact bone. In
the upper part the cells communicate with the antrum; at the middle of the
mastoid process they increase in size. Since the mastoid cells are developed as
outgrowths from the mucous membrane of the middle ear and the antrum, they are
lined by the membrane and are filled with air from these cavities. The cells near
the apex of the mastoid are smaller and do not communicate with those above;
the lowermost cells contain marrow and not air and represent the unaltered
diploe of the cranial bones. Infection from the tympanic cavity may invade
these cells, spread down the mastoid process and invade the deepest-lying
cells. If the formation of air cells (pneumatisation) is complete, the entire
mastoid process is composed of these large air spaces; this is known as the
pneumatic type of mastoid. However, if pneumatisation is interfered with so
that the cells do not develop, the diploic type of mastoid process results, in
which the structure resembles the other cranial bones (outer and nner tables
with diploe between). When this occurs, the antrum is the only cell present. The
sclerotic type of mastoid process is one in which the process is composed of
very dense compact bone and is usually the result of a chronic infection that
has interfered with the absorption of the diploe and the pneumatisation
process. It results in an acellular mastoid that is extremely hard.
FIG.
Simple mastoid operation (antrotomy). The two uppermost figures reveal
the surgical anatomy in the region to be explored. Note the level at
which the section is taken m the figure on the right and then shown in cross
section in the figure on the left. Figures A to E depict the steps in the
operation.
MASTOIDITIS, SIMPLE AND RADICAL MASTOID SURGERY In
mastoiditis, suppurating mastoid cells can involve the lateral sinus. This
involvement may be the result of contamination of the small veins that reach
the sinus through the bone or by direct infection from a perisinus abscess.
From the lateral sinus, extension can take place to the internal jugular vein
or even to the other side of the skull by way of the confluence of sinuses.
Mastoid disease may extend upward through the roof of the antrum, involve the
brain and the meninges and result in meningitis, extradural or brain abscesses.
Mastoiditis usually follows an acute disease of the tympanic cavity because of
the mucous membrane continuity. Once the mastoid cells have become involved,
the infection may spread in one of many ways, traveling either to the
transverse sinus or to the meninges and the brain; the facial nerve may become
involved, or the cortex of the mastoid process itself might be perforated. In
performing a simple mastoid operation (mastoidectomy or antrotomy), it
is possible to injure vital structures. If the opening in the antrum extends
too far upward, the middle cranial fossa may be opened; if too far backward,
the transverse sinus is entered, and if the opening is placed too deep, the
facial nerve may be injured. In doing this operation, an incision is made about
1/2 inch posterior to and parallel with the insertion of the auricle;
separation of the soft parts from the bone subperiosteally is carried
anteriorly to the posterior margin of the auditory canal, superiorly and
anteriorly to the suprameatal spine and posteriorly far enough to expose the
mastoid process. Chiseling is begun in an angle formed by the temporal line
above and the posterior bony wall of the canal in front. The chisel should
always chip in a direction parallel with the auditory meatus. After the antrum
is opened, it is explored, and the opening is enlarged as desired. The diseased
cells and carious bone are removed; the wound is irrigated, dried and packed.
Closure with drainage follows. The radical mastoid operation converts
the mastoid antrum, the cells and the middle ear into a single cavity, and all
the ossicles except the stapes are removed. Auditory (Pharyngotympanic,
Eustachian) Tube. The pharyngotympanic tube is an osseocartilaginous tube
about 1 and 1/2 inches long which connects the tympanic cavity with the
nasopharynx. The posterior third is bony, and the anterior two thirds partly
cartilaginous and partly fibrous. The mucous membrane lining the tube is
continuous with that of the middle ear and the pharynx. Through this tube the
air pressure on both sides of the ear drum is equalized; should the tube become
obstructed by edema, etc., air cannot enter, and a negative pressure results in
the tympanic cavity. With the atmospheric pressure on the outer side of the
drum, the membrane retracts into the cavity and a sensation of fullness in the
ear results. The course of the tube is downward, medially and forward from the
tympanic cavity, its narrowest part, the isthmus, lying at the junction of the
cartilaginous and bony parts. The cartilaginous portion opens from the lateral
wall of the nasal fossa close to the pharyngeal opening and presents medial and
lateral walls which lie so close together that only a slitlike cavity results.
The bony part of the tube is in relation superiorly to the canal of the tensor
tympani muscle, anterolaterally to the petrotympanic fissure, and posteromedially
to the carotid canal and its contents. Normally, the pharyngeal orifice is
closed. During swallowing and yawning it opens by means of the action of the
tensor veli palatine muscle. The tympanic orifice is located in the anterior
wall of the tympanic cavity below the canal for the tensor tympani muscle. Inflation
of the middle ear may be accomplished by Valsalva's method. The
patient closes the mouth and the nose and forcibly blows out the cheeks. This
drives air through the auditory tube, a sense of fullness is felt in the ears
and hearing is diminished because of the resulting distention of the tympanic
membrane. The same may be accomplished by the Politzer method, where the
nozzle of a Politzer bag is inserted into the nostril, and the nose is closed.
The patient then swallows, and the bag is compressed, forcing air into the
tympanum.
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
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.
branches.
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
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
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
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
3.
The mental nerve canal of the mandible also lies
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
6. If
paresthesias are not obtained, anesthesia can be achieved by injecting 5 cc
into the fossa
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
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,
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
3. Richard
M. Stilman,M.D.,E.A.C.S. General Surgery /Review And Assessment/
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.
7. Philip
Thorek. Anatomy In Surgery /J.B.Lippincott Company/,1996.-935p.