LECTURE 2.
OPERATIVE SURGERY OF NECK REGION
The neck-is intermediate link which bridges the head and the trunk. Its area on horizontal section in adult man composes on average 130-140 sq sm. But many anatomical formations are concentrated on this comparatively small space. The numerous vessels, nerves and visceral structures found in the neck make this region both interesting and important to the surgeon.
The upper limits of the neck are the lower border of the jaw, a line extending from the angle of the jaw to the mastoid process, and the superior curved line of the occipital bone. The lower limits are the sternal notch, the clavicles and a transverse line from the acromioclavicular joint to the spinous process of the 7th cervical vertebra. The contour of the neck varies with age and sex, being well rounded in women and children but more angular in men; hence, the landmarks are more conspicuous in the male.
By the frontal plane, which passes through transversal processes of cervical vertebrae, neck is divided into two large parts: anterior and posterior. The anterior portion of the neck contains the respiratory tube (larynx and trachea) and the alimentary tube (pharynx and esophagus); the great vessels and nerves are located on the sides, and the posterior portion contains the cervical segment of the spine and surrounding musculature. The infrahyoid region extends from the hyoid bone above to the suprasternal notch below and is limited laterally by the anterior border of the sternocleidomastoid muscles.
The present of two vascular-nervous fascicles is the basis of division of a neck’s anterior part into two large triangles- anterior and posterior. At anterior triangle passes common carotid artery, jugular vein, vagus nerve. At posterior triangle passes subclaviae arterie and vein, brachial plexus.
The anterior triangle of the neck is bounded in front by the midline of the neck, which extends from the symphysis of the mandible above to the sternal notch below; behind, by the anterior border of the sternocleidomastoid; above, by the lower border of the mandible and a line drawn backward from its angle to the posterior boundary. This triangle is subdivided into 3 subsidiary triangles by the omohyoid.
The digastric triangle is bounded by the anterior belly of the digastric in front, the posterior belly of the same muscle behind, and the border of the mandible above.
The carotid triangle is bounded by the superior belly of the omohyoid below, the sternocleidomastoid behind and the posterior belly of the digastric above.
The muscular triangle is bounded by the superior belly of the omohyoid above, the sternocleidomastoid below, and the midline of the neck in front.
Submental Triangle. That region of the neck which is bounded by the body of the hyoid bone below and the anterior bellies of the digastric on each side forms the submental triangle
The posterior triangle is bounded by the posterior border of the sternocleidomastoid muscle, below by the middle third of the clavicle and behind by the anterior border of the trapezius; the apex of the triangle is the meeting point of the trapezius and the sternocleidomastoid, and when anterior and posterior borders fail to meet on this line, the area is occupied by part of the splenius capitis muscle. The inferior belly of the omohyoid muscle crosses the lower part of the posterior triangle, separating it into an upper, larger occipital triangle and a lower, smaller supraclavicular one. The roof of the posterior triangle is made up of the investing layer of the deep cervical fascia. The floor is muscular and is formed by the following three muscles from above downward: the splenius capitis, the levator scapulae and the scalenus medius. This muscular floor is carpeted by the prevertebral fascia.
STRUCTURES
Skin. The skin of the neck is loosely attached, especially anteriorly. Since it is well supplied with blood vessels, it favors plastic surgery. The skin that covers the posterior region is very thick, adherent and contains numerous sebaceous glands, which explains the frequency of furuncles and carbuncles in this area.
The subcutaneous fatty layer is evenly developed enough, though sometimes in a mental site it is possible to notice the intensified putting of adeps(double chin). On anterior surfase cervival plexus gives branches, in particular n. cutaneus medianus and nn. suprascapulares.
Neck Fasciae:
1. Superficial fascia;
2. proper fascia;
3. deep lamina of the proper fascia;
4. endocervical fascia;
5. prevertebral fascia.
Superficial fascia .It is placed on all surface of a neck, but has a various structure in anterior and posterior portion. Anterior part of the neck Superficial fascia forms a case for platisma and together with its fibers passes on the face and below-in a subclavial region.
Proper fascia- covers anterior and posterior part of the neck. It forms cases for sternocleidomastoid and trapezoid muscles. In submandible triangle she forms case for submandibul glands. In a lateral part proper fascia connected with transversal processes cervical vertebra, owing to that it divides anatomically neck into anterior and posterior parts. And it prevent diffusion of purulent processes from a back site of neck on anterior.
Deep lamina of the proper fascia This fascia has the intermediate position in anterior part of neck between second and fourth fascias. Its form comes nearer to a trapeze and circumscribed on each side by mm.omohyoideus for which forms cases. Fascia started fro hyoid bone forms vagines to muscules– sternohyoid, omohyoid, sternothyroid, thyrohyoid. Fascia attached to an internal surface of a clavicle and sternum.
Endocervical fascia consist of two leaves-parietal and visceral. Visceral covers organs of the neck-pharynx, larynx, esophagus, trachea, thyroid. Parietal forms the vagina for middle vascular-nervous fascicle.
Prevertebral fascia take the beginning from a basis of a skull, passes downwards in thoracic cavity and ends at a level of second thoracic vertebrae. It forms the closed cases for long muscles of the head and neck, besides covers a trunk of a sympathetic nerve. Fascia form vaginas for anterior, medial and posterior scalenus muscules and for lateral vascular-nervous fascicle.
Spaces between fascias filled up by the fat.
Interfascial Spaces:
1. Spatium interaponeuroticum suprasternale; This space is posed above jugular incision of the sternum between 1 and 3 fascia. On each side it is opened and connected with vagine sternocleidomastoid muscule.
2. Spatium m. sternocleidomastoideus; it’s a fissure between back leaf of a vagine sternocleidomastoid muscule and muscle itself which filled up by friable fatty tissue.
3. Saccus ceccus retrosternocleidomastoideus; fatty space between back wall of a vagine sternocleidomastoid muscule and 3 fascia. Medially-the saccus connected with Spatium interaponeuroticum suprasternale.
4. Saccus gl. submandibulare; placed between leafs of 2 fascia.
5. Spatium vasoneurorum; space of middle triangle of the neck. Along vascular-nervous fascicle from each part there is a narrow canal which circumscribed by vagina formed by parietal leaf of 4 fascia.This space started from the basis of the skull and passes in a fat of front mediastinum.
6. Spatium previscerale; placed between parietal and visceral leafs of fourth fascia. It spreads from hyoid bone to jugular incision of the sternum. Here we can fined lymphatic nodes, fat , venous plexus of thyroid gland, in 10-12% arteria thyroid ima. Fat is free connected with a fat of anterior mediastinum.
7. Spatium retroviscerale; between visceral leaf of 4 and 5 fascias. Fatty tissues connected with a fat of posterior mediastinum.
8. Spatium prevertebrale; formed by the fissure between 5 fascia and cervical vertebrae.
9. Spatium anterscalenum; posed in a lateral triangle of the neck between 2 and 5 fascias. Together with a fat here passes subclavian vein , which separated from arteria by anterior scalenus muscules.
10. Spatium interscalenum; between anterior and medial scalenus muscules.
Carotid Arteries. The common carotid artery arises differently on the two sides: the right arises from brachiocephalic trunk behind the sternoclavicular joint; the left originates in the thorax from the arch of the aorta, passes upward and to the left and enters the neck behind the left sternoclavicular joint. This is the largest artery in the neck; and as it passes from behind the sternoclavicular joint, it runs upward and backward under cover of the anterior border of the sternocleidomastoid muscle in the direction of the mandible. When it reaches the level of the upper border of the thyroid cartilage it forms a dilation known as the carotid bulb and then divides into its 2 terminal branches: the internal and the external carotid arteries. The carotid body and the carotid sinus are 2 sensory structures which are frequently confused; they are associated with the region of the carotid bifurcation. The carotid body is a small flattened structure. It is usually found on the posteromedial side of the common carotid artery where it is held firmly in place by connective tissue. It contains numerous nerves and nerve endings and at one time was regarded as part of the chromaffin system. The carotid body represents a specialized sensory organ (vascular chemoreceptor) which responds to chemical changes in the blood and thereby affects cardiovascular output and respiration. Hypoxia and anoxia stimulate this body, resulting in an increase in blood pressure, cardiac rate and respiratory movements. On occasion, tumors arise in the carotid body, which have been referred to as “glomus” tumors. This is a misnomer, since it is not a tumor of arteriovenous origin. The removal of carotid body tumors may be extremely difficult and associated with morbidity and/or mortality. The carotid sinus is usually located at the base of the internal carotid artery and is nerve. composed of numerous and complicated sensory nerve endings. In contrast with the carotid body (chemoreceptor), the carotid sinus is a pressoreceptor. Stimulation of this sinus causes a reduction of blood pressure and a slowing of the heart rate. At times this sinus becomes unduly sensitive to pressure so that a mere turning of the head may drop the blood pressure, slow the heart and produce loss of consciousness. Denervation of the sinus may abolish this so-called carotid sinus syndrome. Throughout the course of the common carotid artery it is imbedded with the internal jugular vein and the vagus nerve, in the connective tissue that constitutes the carotid sheath. The vein lies on the lateral side of the artery and when full of blood overlaps it anteriorly. The vagus nerve lies posteriorly between the artery and the vein. Anteriorly, this artery is covered by the anterior border of the sternocleidomastoid muscle. Between the muscle and the artery in the lower part of the neck the following structures intervene: the superior belly of the omohyoid, the sternohyoid and the sternothyroid muscles. In the upper part of its course the descending ramus of the hypoglossus and the ansa hypoglossi are imbedded in the anterior wall of the sheath, and the common facial vein usually crosses the artery at its termination. Posteriorly, the artery is related to the anterior tubercles of the transverse processes of the lower 4 cervical vertebrae and the muscles that attach here, namely, the scalenus anterior and the longus capitis. It is separated from these structures by the prevertebral fascia and the sympathetic trunk. In the lower part of the neck it lies in front of the vertebral artery as it ascends to the foramen and the transverse process of the 6th cervical vertebra and in front of the inferior thyroid artery, which arches medially to the thyroid gland. On the left side the thoracic duct crosses behind the vessel and below the inferior thyroid artery. Medially, it is related to the inferior constrictor muscle of the pharynx and the thyroid gland. The lobe of the thyroid either lies medial to the artery separating it from the esophagus, the pharynx, the trachea and the larynx or forms a direct anterior relation. Laterally, it is related to the internal jugular vein and the vagus nerve.
The internal carotid artery is the larger of the 2 terminal branches of the common carotid. It is distributed to the brain and to the eye and its appendages. From its origin at the upper border of the thyroid cartilage it passes to the carotid canal of the temporal bone. It turns forward in the cavernous sinus, perforates the dura mater on the inner side of the anterior clinoid process and divides into the anterior and the middle cerebral arteries. Below the posterior belly of the digastric the artery is overlapped by the anterior border of the sternocleidomastoid and the more superficial structures; the hypoglossal nerve, the occipital artery and the common facial vein are interposed between it and the muscle. Above, the artery ascends under cover of the posterior border of the digastric and the stylohyoid and is crossed by the posterior auricular artery. It passes beneath the styloid process and the stylopharyngeus muscle. These 2 structures are placed between the artery and the parotid gland in which the external carotid artery and the posterior facial vein are imbedded. The internal carotid has no branches in the neck. It may be difficult to distinguish between the internal and the external carotid arteries.
The external carotid artery is the smaller of the 2 terminal branches of the common carotid and extends from the upper part of the thyroid cartilage to the neck of the mandible where it divides into its 2 terminal branches—the superficial temporal and the maxillary (internal) arteries. This carotid has been called “external,” not because of its location, which is really internal and superficial to the internal carotid, but because of the fact that it is distributed to parts outside of the skull. Near the angle of the jaw it is crossed by the posterior belly of the digastric and the stylohyoid muscles. Above this it is at first deep to and then enclosed by the substance of the parotid gland where it terminates opposite the neck of the mandible by dividing into its 2 terminal branches. In its short course before entering the substance of the parotid, it is applied to the inferior and the middle constrictor muscles. The vessel has 8 branches: 5 below the digastric muscle and 3 above it.The 5 branches below the digastric muscle are:
1. The superior thyroid artery, which arises from the anterior aspect of the external carotid near its origin. It passes downward and forward under cover of the omohyoid, the sternohyoid and the sternothyroid muscles, parallel with but superficial to the external laryngeal nerve. It reaches the upper pole of the thyroid gland to which it is distributed. Its branches are the infrahyoid, the superior laryngeal, the sternocleidomastoid, the cricothyroid, the isthmic, the glandular and the muscular.
2. The lingual artery arises opposite the greater cornu of the hyoid bone, makes an upward loop, disappears under cover of the hyoglossus muscle and enters the submandibular (submaxillary) region. The loop of this artery is crossed superficially by the hypoglossal nerve.
3. The facial (external maxillary) artery arises near the angle of the mandible, is directed upward and forward on the superior constrictor muscle, beneath the digastric; it continues in a groove on the deep surface of the submandibular gland to the body of the mandible and ascends to the face, anterior to the masseter muscle.
4. The ascending pharyngeal artery arises from the deep aspect of the external carotid close to its origin and continues upward, medial to the internal carotid on the side wall of the pharynx. It is usually small and supplies the pharynx, the soft palate and the meninges.
5. The occipital artery arises from the posterior aspect of the external carotid opposite the facial and continues upward and backward deep to the posterior belly of the digastric. It is crossed by the transverse part of the hypoglossal nerve at its origin, follows the posterior belly of the digastric and is in contact with the skull medial to the mastoid notch, lying deep to the process in the muscles that attach to it. It anastomoses with the deep cervical branch from the costocervical trunk and thus forms a link between the subclavian and the carotid systems.
The branches of the external carotid artery above the digastric muscle are
External and Internal Jugular Veins. The external jugular vein varies in size. It is formed below the lobule of the ear by the union of the posterior auricular vein with a branch of the posterior facial. It begins at the lower part of the parotid gland, runs almost vertically downward, crosses the sternocleidomastoid muscle obliquely, and in the angle between the clavicle and the posterior border of that muscle pierces the deep cervical fascia to which it is firmly bound; it then joins the subclavian vein. It lies upon the superficial layer of deep cervical fascia, beneath the platysma muscle, and at times may be absent or very small. It is so closely associated with the platysma that when the latter is reflected, the vein remains attached to it. If one external jugular is large the other is small; and if both are large, then the internal jugulars are correspondingly small. The external communicates with the internal jugular via a branch which turns around the anterior border of the sternocleidomastoid.
The internal jugular vein begins at the jugular foramen about 1/2 inch below the base of the skull, as a continuation of the sigmoid (transverse) sinus. It passes downward and forward through the neck and ends behind the upper border of the sternal end of the clavicle where it meets the subclavian and forms the innominate vein. It is dilated markedly at its origin, forming the superior bulb that lies in the jugular foramen and the fossa.
NERVES
First anterior branches of 4 cervical nerves create cervical plexus. Four superficial nerves associated with the posterior border of the sternocleidomastoid muscle; they supply the skin of this region. They are derived from the anterior primary rami of the 2nd, the 3rd and the 4th cervical nerves through the branches of the cervical plexus, which lies under cover of the muscle.
Lesser Occipital. The lesser occipital nerve (2nd cervical) appears at the junction of the middle and the upper thirds of the posterior border of the sternocleidomastoid where it hooks around the accessory nerve; it passes upward and backward along the posterior border of that muscle to supply the skin over the lateral part of the occipital region.
Great Auricular. The great auricular nerve (2nd and 3rd cervicals) appears at a slightly lower level, runs parallel with the external jugular vein and enters the nuchal region posterior to the ear; it supplies the skin over the angle of the jaw, the parotid gland, the postero-inferior half of the lateral and the medial aspects of the auricle, and the skin over the mastoid region.
Anterior Cutaneous. The anterior cutaneous nerve (cutaneous colli, 2nd and 3rd cervicals) appears close to the great auricular nerve but runs transversely forward across the sternocleidomastoid and beneath the external jugular vein; it supplies the region about the hyoid bone and the thyroid cartilage.
Supraclavicular. The supraclavicular nerve (3rd and 4th cervicals) appears at a slightly lower level than the preceding ones. The anterior (medial) supraclavicular travels downward and medially across the lower part of the sternocleidomastoid; the middle (intermediate) runs across the clavicle, and the posterior (lateral) extends downward and laterally across the trapezius and the acromial end of the clavicle.
The last four cranial nerves, in their extracranial courses, are located in the region of the digastric muscle.
Vagus. The vagus (10th cranial) nerve leaves the skull through the jugular foramen and at its exit is closely related to the 9th, the 11th and the 12th nerves; the internal jugular vein lies posterior to it, and the internal carotid artery is anterior. In the neck the vagus supplies the alimentary and the respiratory tubes by means of its branches— the pharyngeal, the superior and the recurrent laryngeal.
Glossopharyngeal. The glossopharyngeal nerve (9th cranial) leaves the skull through the jugular foramen with the vagus and the accessory, but in its own sheath of dura mater. It descends between the internal jugular and the internal carotid vessels to the lower border of the stylopharyngeus around which it winds and then passes forward between the internal and the external carotid arteries. Its one motor branch supplies the stylopharyngeus muscle.
Spinal Accessory. The spinal accessory nerve (11th cranial) has a double origin: spinal and cranial. The spinal part arises from the upper 5 or 6 segments of the spinal cord, and the cranial is accessory through the vagus. It makes an abbreviated appearance in the carotid triangle between the digastric and the sternocleidomastoid muscles. As it enters the deep surface of the sternocleidomastoid about
Hypoglossal. The hypoglossal nerve (12th cranial) is the motor nerve of the tongue. It emerges from the skull through the anterior condylar (hypoglossal) canal in the occipital bone and is in close contact with the 9th, the 10th and the 11th cranial nerves. It lies between the internal jugular vein and the internal carotid artery and, as it descends, is closely related to the vagus until it appears at the lower border of the posterior belly of the digastric. Here it turns forward and medially and crosses, in turn, the internal carotid, the occipital and the external carotid arteries and the loop of the lingual artery. As it crosses the lingual artery, the hypoglossal nerve is crossed superficially by the common facial vein, passes deep to the posterior belly of the digastric and the submaxillary gland and enters the submandibular region where it is distributed to the muscles of the tongue. As the nerve continues forward, it comes to lie superficial to the hyoglossus muscle which separates it from the lingual artery, then continues in an intermuscular cleft between the hyoglossus and the mylohyoid to the muscles of the tongue. The ascending branch of the hypoglossal nerve leave its parent trunk where it bends forward to cross the carotid vessels. The descending branch continues downward on the surface of the internal and the common carotid arteries and is imbedded in the anterior wall of the carotid sheath. From its lateral side it is joined by the descending cervical nerve (2nd and 3rd cervicals) which arises from the cervical plexus, and the nerve loop so formed constitutes the ansa hypoglossi. Branches from this ansa are distributed to the sternohyoid, the sternothyroid and both bellies of the omohyoid. The thyrohyoid receives its owerve from the first cervical via the hypoglossal.
Cervical Plexus. This plexus should not be confused with the cervical sympathetic groups. The plexus lies on the scalenus medius and the levator anguli scapulae under cover of the sternocleidomastoid muscle. It is formed by the upper 4 cervical nerves, all but the first of which divides into 2 parts. A branch from each nerve joins the superior cervical ganglion. These nerves are combined in irregular series of loops under cover of the sternocleidomastoid. The roots of the plexus lie deep to the prevertebral fascia and are frequently injured in radical neck surgery. The terminal branches pierce the fascia and continue to the muscles which they supply and the nerves with which they connect. The superficial cutaneous branches radiate from the plexus and appear in the supraclavicular region as they wind around the posterior margin of the sternocleidomastoid muscle.
Phrenic Nerve. Of the muscular or deep branches, the phrenic is the most important. It is derived from the 4th cervical, but receives additional fibers from the 3rd and the 5th. It passes downward in the neck and lies deep to the prevertebral fascia, traveling on the anterior scalene muscle; it enters the thorax at the root of the neck on its way to the diaphragm.
Superficial Branches of the Cervical Plexus. These branches, all cutaneous, are the cutaneous colli, the lesser occipital, the great auricular and the descending supraclavicular nerves. The deep branches are muscular and divide into anterior and posterior branches. The anterior branch supplies the thyrohyoid, the geniohyoid, the rectus capitus lateralis, the rectus capitis anterior, the longus capitis, the longus colli, the scalenus anterior and the intertrans– versalis. The posterior branch supplies the sternocleidomastoid, the levator scapulae, the trapezius and the scalenus medius muscles. Communicating branches also are found which travel to the sympathetics and the hyoglossal muscle.
Cervical Sympathetic. This group consists of 3 ganglia with connecting branches which form a chain lying behind the carotid sheath and upon the prevertebral fascia. It extends from beneath the mastoid process to the 1st rib. The ganglia are known as the superior, the middle and the inferior and have been called, respectively, carotid, thyroid and vertebral from their almost constant association with these arteries. The superior or carotid is the largest ganglion in the neck. It lies in front of the transverse processes of the 2nd and the 3rd cervical vertebrae on the longus capitis and behind the carotid sheath. It is fusiform in shape and sends a branch downward to connect with the middle ganglion. The middle or thyroid ganglion is the smallest of the 3, and some authors state that it is inconstant or absent. This error may be due to the fact that the ganglion sometimes occupies a lower position, nearer the inferior ganglion of which it has been considered a part. It lies on a level with the 6th cervical vertebra in front of or behind the inferior thyroid artery. The inferior or vertebral ganglion is next
in size to the superior. It is found behind the vertebral artery, between the neck of the 1st rib and the transverse process of the 7th cervical vertebra. At times it unites with the first thoracic sympathetic ganglion to form the stellate ganglion. Since it is beneath the vertebral artery, just as the latter is given off from the subclavian, it makes surgical approach to the ganglion difficult. Some of the fibers that connect the middle with the inferior cervical ganglion descend in front of the subclavian artery and then upward behind it to form the so-called ansa subclavia.
