Posterior Triangle of the Neck Dr. Lubna Nazli

Objectives Describe the anatomy of posterior triangles of neck List the fascial layers of neck, and the major structures that they enclose Identify major neurovascular structures in the neck, including external / internal jugular and subclavian veins, common / external / internal carotid and subclavian arteries, proximal brachial plexus, cervical plexus, and lymphatics

Cervical Fascia Consists of: 1- superficial fascia 2- deep cervical fascia a. superficial (investing) layer b. pretracheal layer c. prevertebral layer

Superficial Cervical Fascia - immediately deep to the skin of the neck - encloses the platysma muscle - is continuous with that of the head and thorax - It contains A. cutaneous nerves, B. superficial Lymph nodes, C. superficial vessels, D. fat

1- investing fascia Deep cervical fascia -surrounds all structures in the neck - between superficial fascia and the muscles -splits to enclose the trapezius and Sternocleidomastoid muscles -splits superiorly to enclose the parotid and submandibular glands

*Suprasternal Space space between the 2 layers of deep fascia just above the manubrium which encloses sternal head of Sternomastoid Inf. end of the anterior jugular veins jugular venous arch fat few lymph nodes

2-pretracheal fascia - limited to the anterior part of the neck - completely surrounds the thyroid gland - forming a sheath for the thyroid gland - binds the gland to the larynx

pretracheal fascia encloses the parathyroid glands, trachea, pharynx, esophagus and Infrahyoid muscles inferiorly blends with the fibrous pericardium laterally with the carotid sheath superiorly attaches to the thyroid cartilage and hyoid bone

3-Prevertebral fascia tubular sheath for the vertebral column and its related muscle from base of the skull to T3, where it fuses with the anterior longitudinal ligament of the thoracic vertebrae extends laterally as the axillary sheath

Retropharyngeal Space -the largest and most important interfascial space in the neck -It is a potential space consisting of loose connective tissue -it is between 1-prevertebral fascia, and 2-Bucchopharyngeal fascia ( covers the pharynx superficially and the buccinator muscle) -Closed superiorly by the base of the skull -Opens inferiorly into the superior mediastinum -Permits the movements of the pharynx, larynx, esophagus, and trachea during the swallowing Infection in the retropharyngeal space may extend inferiorly into the Superior mediastinum

Triangles of the neck

SCM divides the neck Into 2 triangles 1-anterior 2-posterior

Posterior Triangle of the Neck Boundaries: Anterior border posterior border of the SCM Posterior border anterior border of the trapezius muscle Base intermediate 1/3 of the clavicle Apex meeting of the anterior and posterior border

Roof 1-skin 2-the superficial fascia which contains a) platysma b) external jugular vein c) cutaneous branches of the cervical plexus 3-the deep fascia

Floor 2- levator scapula 3- scalenus posterior 4- scalenus medius 1- splenius capitis 2- levator scapula 3- scalenus posterior 4- scalenus medius 5- scalenus anterior All covered by the prevertebral fascia Small part of the semispinalis muscle may appear at the apex of the triangle

2- subclavian triangle (supraclavicular) *subdivided by the inferior belly of the omohyoid muscle Into : 1-occipital triangle 2- subclavian triangle (supraclavicular)

Occipital triangle Inferior belly of omohyoid Supraclavicular triangle

Occipital triangle Bounded by – Anterior border of trapezius muscle – Posterior border of sternocleidomastoid muscle – inferior belly of omohyoid

Supraclavicular triangle Bounded by – Omohyoid muscle – The clavicle – Sternocleidomastoid muscle

*Contents A-Muscles the inferior belly of the omohyoid m

B-nerves *Accessory nerve Descends on the surface of the levator scapulae *Nerves to the levator scapulae from the ventral rami of C3 and C4 *Cutaneous branches of the cervical plexus

B-nerves *Roots and trunks of the brachial plexus Supraclavicular nerve Suprascapular nerve Dorsal scapular nerve Long thoracic nerve Nerve to subclavius

veins arteries -Transverse cervical vessels -Suprascapular vessels -Subclavian artery crossing the first rib veins External jugular vein

Platysma muscle Origin deep fascia that covers the pec major and deltoid ms Insertion into the lower border of the mandible some fibers to the Face which blend with the muscle at the angle of the mouth Nerve supply cervical branch of facial nerve Action -depresses the mandible -draws down the lower lip

Omohyoid muscle: Origin Inferior belly upper margin of the scapula medial to suprascapular lig. Superior belly lower border of body of hyoid bone Insertion intermediate tendon ( clavicle and 1st rib by facial sling) Nerve supply Ansa Cervicalis (C1,2 and 3) Action depresses hyoid bone

Sternocliedomastoid(SCM) Origin manubrium and medial 1/3 of the clavicle (sternal head and Clavicular head)) Insertion mastoid processes of temporal bone and occipital bone Nerve supply 1-spinal part of the accessory nerve (motor) 2-C2 and C3 (sensory) Action -two muscles acting together extend the head and flex the neck -one muscle rotates head to opposite side

What is torticollis? Torticollis (wry neck) is a congenital or acquired condition of limited neck motion in which the child will hold the head to one side with the chin pointing to the opposite side. It is the result of the shortening of the sternocleidomastoid (neck) muscle. In early infancy, a firm, non-tender mass may be felt in the midportion of the muscle. The mass will go away and be replaced with fibrous tissue. If untreated, there can be permanent limitation of neck movement. There may be flattening of the head and face on the affected side.

The veins: -External jugular vein: begins just behind the angle of the mandible -it is deep to the platysma muscle -is formed by union of 1-Posterior Auricular vein 2-Post. Division of the Retromandibular v. - drain into the subclavian vein.

Retromandibular vein Is formed by the superficial temporal and maxillary veins Divides into an anterior branch, which joins the facial vein to form the common facial vein, and a posterior branch, which joins the posterior auricular vein to form the external jugular vein

Tributaries of EJV . Posterior auricular vein . Post.division of the Retromandibular vein . transverse cervical vein, . suprascapular vein . anterior jug.vein

*Superficial cervical LN -lie along the external jugular vein in the posterior triangle, and along the anterior jugular vein in the anterior triangle -superficial to the SCM -Drains into deep cervical LN -Receives Lymph vessels from the occipital and mastoid LNs

a rudimentary cervical rib a tight fibrous band first thoracic rib The brachial plexus and subclavian artery may be compressed in the neck by a rudimentary cervical rib a tight fibrous band first thoracic rib a tight scalenus anterior muscle giving rise to sensory, motor vascular symptoms in one or both upper extremities.

cervical rib Pressure in the region of a cervical rib will give rise to local pain as well as pain referred to the hand and arm particularly in the ulnar portion of the hand and forearm since it is the lower trunk of the brachial plexus which is involved (C8,T1). There is muscular weakness of the small hand muscles.

Nerves: B-The branches of the Cervical Plexus A-The Accessory nerve B-The branches of the Cervical Plexus C-The Roots and the Trunks of the Brachial Plexus

Nerves:

What structures are contained within the posterior triangle of the neck? Posterior triangle of neck Muscles ( SCM, Trapezius, Omohyoid & floor muscles) Accessory nerve 3 trunks of brachial plexus Cervical plexus External jugular vein Subclavian artery Deep cervical lymph nodes (what is Virchow’s node? )