POSTERIOR TRIANGLE OF. NECK. • Boundaries. – Infront – posterior border of sternocleidomastoid muscle. – Behind – anterior border of trapezius. 3 days ago The posterior triangle of the neck (also known as the lateral cervical region), is a region of the neck. Borders. Its boundaries are as follows. The posterior triangle is a region of the neck. Side of neck, showing chief surface markings. (Nerves are yellow, arteries are It has the following boundaries.
Posterior triangle of the neck - Wikiwand
Most of the branches arise from the first part of the subclavian artery. They are described in the following paragraphs: The vertebral artery fig. Arising medial to the anterior scalene, it ascends through the foramina transversaria of the C6 to C1 vertebrae, passes posterior to the lateral mass of the atlas see fig.
It penetrates the posterior atlantooccital membrane and enters the cranial cavity by passing superiorly through the foramen magnum. At the lower border of the pons, it unites with the vessel of the opposite side to form the basilar artery, which ends by dividing into the two posterior cerebral arteries. The course of the vertebral artery may be considered in four parts: The cervical part ascends posterior to the common carotid artery in the pyramidal space between the longus colli and anterior scalene see Fig.
The vertebral part ofthe artery, accompanied by a venous plexus and sympathetic nerve fibers, gives branches to the spinal cord and vertebrae. The suboccipital and intracranial parts of the vertebral artery have been described already. The internal thoracic artery is described with the thorax.
The thyrocervical trunk divides almost at once into three branches: It is closely related to the middle cervical ganglion and the recurrent laryngeal nerve.
Absence of Posterior Triangle: Clinical and Embryological Perspective
It enters the posterior surface of the thyroid gland. The inferior thyroid artery gives branches to the vertebrae ascending cervical arterylarynx inferior laryngeal arterytrachea, pharynx, esophagus, and thyroid gland.
It gives off suprasternal, acromial, and articular branches. It supplies the trapezius as the superficial cervical artery. The costocervical trunk arches over the cupola of the parietal pleura to reach the neck of the first rib, where it divides into two branches: The dorsal scapular artery generally passes between the trunks of the brachial plexus and accompanies the dorsal scapular nerve to the rhomboid muscles.
It may, however, be replaced by a deep branch of the transverse cervical artery. Abnormal compression of the subclavian or axillary vessels, the brachial plexus, or both produces the signs and symptoms of the "neurovascular compression syndromes" of the upper limb often generically called "thoracic outlet syndromes".
The features of vascular compomise may include pain, paresthesia pricklingnumbness, weakness, discoloration, swelling, ulceration, and gangrene, may be produced also by other causes. The neurovascular bundle to the upper limb is liable to be compressed: Cupola of pleura see fig. It begins at the inlet of the thorax along the sloping internal border ofthe first rib see fig. The cupola and apex of the lung project into the root of the neck up to about 3 cm above the medial third of the clavicle.
The cupola is covered by fascia, the suprapleural membrane attached to the first rib and to C. The cupola and apex of the lung occupy the pyramidal interval between the scalene muscles and the longus colli and are posterior to the subclavian vessels and anterior scalene. Sympathetic trunk see figs. The preganglionic fibers leave in the ventral roots and pass through rami communicantes to the thoracic part of the sympathetic trunk. They then ascend to the cervical part of the sympathetic trunk, where they synapse.
Postganglionic fibers are distributed to the blood vessels, smooth muscle, and glands of the head and neck. The cervical part of the sympathetic trunk consists of three or four ganglia connected by an intervening cord or cords. Postganglionic fibers leave the trunk by gray rami communicantes and also in branches that go directly to blood vessels or viscera. Any cause of interruption of sympathetic nerve impulses to the head, including damage to the cervical part of the sympathetic trunk, produces Horner's syndrome: The preganglionic fibers for the eye and orbit are probably from T1 range: C8 to T4and they probably enter the cervicothoracic ganglion.
A local anesthetic injected near the cervicothoracic ganglion will "block" the cervical and upper thoracic ganglia stellate ganglion blockthereby relieving vascular spasm involving the brain or an upper limb. Cervical ganglia see figs. The superior cervical ganglion lies inferior to the base of the skull and posterior to the internal carotid artery. It distributes postganglionic fibers to cranial nerves IX-XII and cervical nervesthe carotid sinus and body, the pharyngeal plexus and larynx, and the heart.
A plexus on the external carotid artery is continued on its branches to the salivary glands. A large ascending branch from the ganglion, the internal carotid nerve, accompanies the internal carotid artery and forms a plexus that contributes to several cranial nerves, the tympanic and greater petrosal nerves, the ciliary ganglion pupillodilator fibersand the anterior and middle cerebral arteries. The middle cervical ganglion, usually superior to the arch of the inferior thyroid artery, is very variable.
The vertebral ganglion generally lies anterior to the vertebral artery and inferior to the arch of the inferior thyroid artery.
Cords connect this ganglion with those above and below, and another cord, the ansa subclavia, loops around and forms a plexus on the first part of the subclavian artery. The cervicothoracic stellate ganglion comprises two variably fused components: It lies posterior to the vertebral artery and anterior to the C7 transverse process and the neck of the first rib. Preganglionic rami come from the T1 nerve, and postganglionic gray rami go to cervical nerves and the T1 nerve.
These fibers enter the brachial plexus and are distributed to the upper limb. Other branches of the ganglion go to the heart and to the subclavian and vertebral arteries. The vertebral plexus is ultimately distributed along the basilar artery. The plexuses on the posterior cerebral arteries may be derived from the vertebral or internal carotid plexuses. Internal jugular vein fig. It commences in the jugular foramen as the continuation of the sigmoid sinus.
At the base of the skull, the internal carotid artery in the carotid canal lies anterior to the internal jugular vein in the jugular foramenand the two vessels are there separated by cranial nerves IX-XII see fig. The internal jugular vein descends in the carotid sheath and is hidden by the sternomastoid muscle. The internal and common carotid arteries accompany the vein medially, and the vagus lies posterior to and between the vein and the arteries.
The deep cervical lymph nodes lie along the course of the internal jugular vein. The vein passes deep to the interval between the two heads of the sternomastoid muscle see fig. Dilatations are found at its beginning and near its end superior and inferior bulbs. The tributaries, which are variable, include the inferior petrosal sinus and the pharyngeal, lingual, and superior and middle thyroid veins. The right lymphatic duct or on the left the thoracic duct opens usually into the internal jugular vein at or near its junction with the subclavian vein.
Thoracic duct The thoracic duct receives the lymph from most of the body, including the left side of the head and neck. It receives the left jugular trunk and ends variably anterior to the first part of the left subclavian artery in or near the angle between the left internal jugular and subclavian veins.
The right lymphatic duct receives the lymph from the right side of the head and neck, right upper limb, and right side of the thorax. This duct, which is seldom present as a single structure fig. Lymphatic drainage of head and neck All the lymphatic vessels from the head and neck drain into the deep cervical nodes, either 1 directly from the tissues or 2 indirectly after traversing a more superficial group of nodes. Several of these groups of lymph nodes form a "pericervical collar" at the junction of the head and neck fig.
The superficial tissues drain into these groups and also into the superficial cervical nodes. The superficial cervical nodes are in 1 the posterior triangle along the external jugular vein and 2 the anterior triangle along the anterior jugular vein. The deep cervical nodes include several groups, the most important of which forms a chain along the internal jugular vein, mostly under cover of the sternomastoid muscle.
The jugulodigastric node lies on the internal jugular vein immediately inferior to the posterior belly of the digastric.
Posterior Triangle of the Neck - Subdivisions - TeachMeAnatomy
It receives important afferents from the posterior tongue and from the tonsils. The jugulo-omohyoid node lies on the vein immediately superior to the middle tendon of the omohyoid.
It receives afferents from the tongue. One group of deep nodes is found in the posterior triangle and is related to the accessory nerve. Other groups are prelaryngeal, pretracheal, paratracheal, and retropharyngeal.
These take part in the drainage of deeper structures e. The efferent vessels from the deep cervical nodes form the jugular trunk, which usually joins the thoracic duct on the left and enters the internal jugular-subclavian junction on the right. Cervical plexus The ventral rami of cervical nerves unite to form the cervical plexus, whereas those of cervical nerves and the first thoracic nerve form the brachial plexus.
The cervical plexus is an irregular series of loops from which the branches arise. Cutaneous areas and muscles are thereby supplied by more than one spinal nerve table The cutaneous branches all emerge near the middle of the posterior border of the sternomastoid muscle see fig.
The cervical plexus lies anterior to the levator scapulae and middle scalene, under cover of the internal jugular vein and the sternomastoid. The ventral rami receive postganglionic rami communicantes from the cervical sympathetic ganglia.
The ansa cervicalis is a loop on or in the carotid sheath. It is formed by fibers of cervical nerves see figs. It has a superior root, which descends from the hypoglossal nerve but consists of spinal fibersand an inferior root, which connects the ansa with cervcial nerves 2 and 3.
The ansa and its superior root supply the infrahyoid muscles but the thyrohyoid receives its cervical fibers directly from the hypoglossal nerve. The phrenic nerve arises chiefly from C4 and supplies the diaphragm and the serosa of the thorax and abdomen. It often has a root from C3 and usually an accessory root from C5 see fig. The phrenic nerve, formed at the lateral border of the anterior scalene, descends on the anterior surface of that muscle see fig.
It lies deep to the prevertebral fascia, is crossed by the transverse cervical and suprascapular arteries fig. It passes between the subclavian artery and vein see fig. Damage to the phrenic nerve collapses a lung by paralyzing and thereby elevating the hemidiaphragm. The subclavian artery passes posterior to the anterior scalene, whereas the phrenic nerve lies on the muscle. The anterior scalene arises from the anterior tubercles; the middle and posterior scalene the latter often absent or blended with the middle arise from the posterior tubercles of the cervical transverse processes.
The ventral rami of the cervical nerves emerge between the anterior and posterior tubercles; hence the brachial plexus emerges between the anterior scalene and the middle scalene. The scalenes may act as muscles of inspiration even during quiet breathing; they become active during strong expiratory effects, and they may be important in coughing and straining.
A pyramidal interval occurs between the scalemes laterally and the longus colli medially, and into this the pleura and apex of the lung project upward fig. The fascia of the neck comprises three layers: The investing layer is attached to the major bony prominences: The layer surrounds the trapezius, roofs the posterior triangle, surrounds the sternomastoid, and roofs the anterior triangle. It forms the sheaths of the parotid and submandibular glands. At the manubrium, it bounds the suprasternal space, which encloses the sternal heads of the sternomastoid and the jugular venous arch.
The visceral pretracheal layer, limited to the anterior neck, is more extensive than its name suggests. It lies inferior to the hyoid bone and is attached to the oblique lines of the thyroid cartilage and to the cricoid cartilage. It surrounds the thyroid gland, forming its sheath, and it invests the infrahyoid muscles and the air and food passages. Infections from the head and neck can spread anterior to the trachea or posterior to the esophagus and reach the superior mediastinum in the thorax.
The prevertebral layer is attached to the base of the skull and to the transverse processes of the cervical vertebrae. It covers the pre vertebral muscles, scalenes, phrenic nerve, and deep muscles of the back, and therefore the floor of the posterior triangle. Anterior to the subclavian artery, it is prolonged laterally as the axillary sheath, which also invests the brachial plexus. The carotid sheath, which is fused with all three layers of the cervical fascia, is a condensation around the common and internal carotid arteries, internal jugular vein, and vagus nerve.
Prevertebral muscles see table The longus capitis, which covers the superior part of the longus colli, extends from the inferior cervical vertebrae to the occipital bone. The longus colli see fig. The recti capitis anterior and lateralis connect the atlas to the occipital bone.
The longus colli is active during talking, coughing, and swallowing. The pre vertebral muscles and sternomastoid muscles act with, and as antagonists to, the upper deep muscles of the back. Questions Why is the sternomastoid known officially as the sternocleidomastoid muscle? Actually, the muscle is therefore sternomastoid and cleido-occipital and there are deeper cleidomastoid fibers.
The muscle is the anatomical and clinical key to the neck, dividing it into anterior and posterior triangles. The development of the sternomastoid muscle and trapezius is complicated J.
The Anterior Triangle of the Neck
The triangle contains the external carotid artery and its three anterior branches facial, lingual, and superior thyroidthe hypoglossal nerve, and the greater horn of the hyoid see figs. More deeply placed are the superior laryngeal nerve and C. The common and internal carotid arteries, together with the internal jugular vein and vagus, generally lie under cover of the sternomastoid and therefore, strictly speaking, are posterior to the triangle.
Thus hyoid means U-shaped; thyroid, shield-shaped; cricoid, ring-shaped; arytenoid, pitchershaped; sphenoid, wedge-shaped; pterygoid, wing-like; and clinoid, shaped fancifully like a bed. In thyroidectomy, the gland and its capsule are removed. Preservation of the parathyroid glands can be ensured by leaving the posterior part of each thyroid lobe in place.
The condition is endemic in certain regions. Because of "the variability rather than the vulnerability" Berlin of the nerve, injury may occur during thyroid surgery. Examples of the extensive literature are P. Parts of the embryonic thyroglossal duct may remain as cysts, the pyramidal lobule, and accessory thyroid tissue e.
Thyroglossal cysts are in, or close to, the median plane, and they may be found at any level between the mouth and the cricoid cartilage. In the presence of a median swelling in the neck, thyroglossal cysts and enlarged lymph nodes should be kept in mind. For a lateral swelling, cysts of pharyngeal pouch origin and tuberculous nodes, should be considered. Rarely, the thyroid fails to descend and develops in the tongue lingual thyroid.
Examples are given by D. Hence the isthmus of the thyroid gland is retracted or incised. In an emergency, cricothyrotomy is considered preferable for non-surgeons. Variations are given by D. The carotid surface line indicates also the approximate position of the internal jugular vein, vagus, and sympathetic trunk. These accessory fibers are believed to include those 0 in the pharyngeal branches of the vagus that supply most of the muscles of the pharynx and soft palate, 2 in the external branch of the vagus that innervates the cricothyroid muscle, and 3 in the recurrent laryngeal nerves of the vagus that supply the muscles of the larynx see fig.
Accessory fibers in the vagus are tested by asking the subject to say "ah": Laryngoscopy reveals the condition of the vocal folds. It is tested by asking the subject to protrude the tongue. The collateral circulation to the upper limb e.
These preganglionic fibers ascend in the trunk to reach and synapse in the three or four cervical ganglia fig. Detailed accounts are available: Several articles on special regions have appeared, e. Figure legends Figure Surface anatomy of the neck. The sternal and clavicular heads of the sternomastoid muscles are clearly visible.
On each side, the anterior triangle of the neck is bounded by the anterior border of the sternomastoid, the anterior median line of the neck, and the lower border of the mandible. Figure Triangles of the neck. A shows the platysma, which roofs parts of both the anterior and posterior triangles. B shows the division of the neck by the sternomastoid into anterior and posterior triangles. C and D show the subdivisions of the triangles.
Figure Posterior triangle of the neck.Anterior Triangle of the Neck
The brachial plexus meets and follows the subclavian artery. The third part of the subclavian artery is the site for compression. Figure The cutaneous branches of the cervical plexus. The vertical line represents the posterior border of the sternomastoid: After von Lanz and Wachsmuth. Figure Superficial veins of the head and neck.
Variations are very common. The internal jugular vein can be seen deep to the sternomastoid. Figure Suprahyoid and infrahyoid muscles. For the geniohyoid, see figs. The infrahyoid muscles are innervated mainly by the ansa cervicalis.
Figure Cervical vertebrae. Note the translucency of the larynx and trachea. Note the anterior and posterior arches of the atlas, the curve of the cervical column and the slopes of the articular facets. The teeth display metallic fillings. Figure The main structures that cross the thoracic inlet. In addition to various vessels, note the recurrent laryngeal nerves and on the left side the thoracic duct. Figure A, The thyroid gland, anterior aspect. B, Horizontal section through the line shown in A, showing the relationships of the thyroid gland, after von Lanz and Wachsmuth.
Figure Scintigram of the thyroid gland produced by uptake of a radioisotope. The right and left lobes are united by the isthmus. Saunders Company, Philadelphia,courtesy of the authors. Figure The blood supply of the thyroid gland. Only the arteries are shown on one side and only the veins on the other.
Most anastomotic vessels are omitted. Figure The carotid arteries in the neck. A, Important bony landmarks. B, The sternomastoid and underlying great vessels. Note the internal jugular vein in the interval between the heads of the sternomastoid below.
C, The carotid arteries. Note the branches of the external carotid artery. Figure The carotid sinus and its innnervation from the glossopharyngeal and vagus nerves and from the sympathetic trunk. Figure The last four cranial nerves below the base of the skull. The glossopharyngeal nerve passes between the carotid arteries.
The vagus descends between the jugular vein and the internal and common carotid arteries, the accessory nerve crosses the internal jugular vein.
The hypoglossal nerve, superficial to the great vessels, winds around the origin of the occipital artery. The maxillary artery disappears deep to the neck of the mandible. Figure Summary of the branches of the last four cranial nerves in the head and neck. Figure The glossopharyngeal nerve. Figure The vagus and phrenic nerves, anterior aspect. Note the different levels of origin of the right and left recurrent laryngeal nerves.
The anterior scalene muscle is depicted on each side. The thoracic duct can be seen terminating on the left side of the body. Figure The vagus nerve. Figure The vagus and accessory nerves.
The superior and inferior ganglia of the vagus are shown above and below the jugular foramen, respectively. Figure The hypoglossal nerve. Figure The branches of the subclavian artery: The second part of the subclavian artery is shaded. Figure Cervical ribs. A, An unusually long transverse process of C7 arrow. B, A minute cervical rib with head, neck, and tubercle. C, A cervical rib bound to the first rib: After von lanz and Wachsmuth. Figure The vertebral artery, a branch of the subclavian, presents cervical, vertebral, suboccipital, and intracranial parts.
It unites with its fellow of the opposite side to form the basilar artery, which divides into the right and left posterior cerebral arteries.
Figure The right sympathetic trunk in the neck, lateral aspect. Only cervical nerves 1 to 5 are shown. The numerals on the left side of the drawing refer to those cervical and thoracic nerves to which rami communicantes postganglionic fibers are given. The numerals on the right side refer to the cervical vertebrae. The subclavian in transverse section and vertebral arteries are shown. Figure The internal jugular vein and its tributaries.
Note the valves at the terminations of the subclavian and internal jugular veins: Figure A, A horizontal section in which the arch formed by the thoracic duct is seen between the anterior scalene muscle posterior and the internal jugular vein and common carotid artery anterior The phrenic nerve is visible on the anterior scalene. B, The termination of the thoracic duct, anterior aspect. Figure The lymphatic drainage of the head and neck.
A, The superficial groups of cervical lymph nodes. The wide, shaded band indicates the "pericervical collar" of nodes. Each circle represents a group of nodes. The arrows show the direction of drainage.
B, The deep cervical lymph nodes. The drawing at the lower right shows one of many patterns that may be found on the left side of the body. Figure A, The cupola of the pleura, anterior scalene, and longus colli; anterior aspect and slightly from the right side. Each side of the neck is divided into two major well-known triangles, i. Boundaries of anterior triangle Laterally, by anterior border of sternocleidomastoid muscle and medially by midline, and superiorly by lower border of mandible.
Boundaries of posterior triangle Anteromedially by posterior border of sternocleidomastoid muscle, posterolaterally by anterior border of trapezius muscle and inferiorly by clavicle. Both these triangles are covered by deep fascia of neck and only after the removal of this fascia the secondary triangles of each neck comes into view.
Posterior triangle is subdivided into occipital triangle and subclavian omoclavicular triangle. This triangle is bounded posteriorly by internal jugular vein, common facial vein anteroinferiorly, and hypoglossal nerve forms base for this triangle superiorly [Figure 1]. Contents of this triangle are one branch of common carotid artery or carotid bifurcation, jugulodiagastric lymph node.
Schematic drawing of Farabeuf's triangle Click here to view Submandibular triangle is bordered superiorly by inferior border of the body of the mandible and lies between anterior and posterior belly of digastric muscle.
Submandibular triangle is subdivided into an anterior and posterior part by stylomandibular ligament submandibular gland is the main content of this triangle and present in anterior part of this triangle, superficial to which is anterior facial vein and beneath the gland, on the surface of mylohyoid muscle, are submental artery and mylohyoid nerve and vessels.
In the posterior part of this triangle is external carotid artery, ascending deep into the substance of parotid gland. Lesser's Triangle It is a triangle contained within the submandibular triangle. Its boundaries are the hypoglossal nerve, and the anterior and posterior belly of the digastric muscle [Figure 2]. This triangle was named after a German surgeon named Ladislaus Leon Lesser, who lived from to Anterior belly of digastric and intermediate tendon of digastric forms the inferior boundary, superior border by hypoglossal nerve and posterior border is formed by posterior margin of mylohyoid muscle at the intermediate tendon of digastric muscle.
Floor of this is formed by hyoglossus and mylohyoid muscles. Schematic drawing of Lesser's, Beclard's and Pirogoff's Triangle adopted from Tubbs et al Pirogoff's Triangle It was named after Russian surgeon and scientist Nikolai I Pirogoff —who performed the first description of this anatomic area of the neck. Following are the boundaries of this triangle: Superior boundary is formed by hypoglossal nerve, inferior boundary is formed by intermediate tendon of digastric muscle and posterior border is formed by posterior border of mylohyoid muscle [Figure 2].
It is also considered that this triangle is posterior continuation of Lesser's triangle. Greater cornu of hyoid bone forms the inferior boundary, posterior belly of digastric muscle forms superior boundary, and posterior border of hyoglossus muscle forms posterior boundary and its base [Figure 2].