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Posterior Triangleof the Neck

Dr. Lubna Nazli

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ObjectivesObjectives

Describe the anatomy of posterior triangles Describe the anatomy of posterior triangles of neckof neck

List the fascial layers of neck, and the major List the fascial layers of neck, and the major structures that they enclosestructures that they enclose

Identify major neurovascular structures in Identify major neurovascular structures in the neck, including external / internal jugular the neck, including external / internal jugular and subclavian veins, common / external / and subclavian veins, common / external / internal carotid and subclavian arteries, internal carotid and subclavian arteries, proximal brachial plexus, cervical plexus, proximal brachial plexus, cervical plexus, and lymphaticsand lymphatics

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Cervical Fascia

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

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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

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Deep cervical fascia

1- investing 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

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*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

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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

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•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

pretracheal fascia

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•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

3-Prevertebral fascia

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-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 swallowingInfection in the retropharyngeal space may extend inferiorly into the Superior mediastinum

Retropharyngeal Space

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Triangles of the neck

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SCMdivides the neck Into2 triangles 1-anterior 2-posterior

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Posterior Triangle of the Neck

Boundaries:Anterior border posterior border of the SCM

Posterior borderanterior border of thetrapezius muscle

Base intermediate 1/3 of the clavicle

Apex meeting of the anterior and posterior border

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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

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Floor

1- splenius capitis 2- levator scapula 3- scalenus posterior 4- scalenus medius 5- scalenus anterior

All covered bythe prevertebral fascia

Small part of the semispinalis muscle may appear at the apex of the triangle

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

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Occipitaltriangle

Supraclaviculartriangle

Inferior belly of omohyoid

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Occipital triangle

Bounded by – Anterior border of trapezius muscle – Posterior border of

sternocleidomastoid muscle – inferior belly of omohyoid

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Supraclavicular triangle

Bounded by – Omohyoid muscle – The clavicle – Sternocleidomastoid muscle

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*ContentsA-Muscles the inferior belly of the omohyoid m

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B-nerves *Accessory nerveDescends on the surface of the levator scapulae

*Nerves to the levator scapulaefrom the ventral rami of C3 and C4

*Cutaneous branches of the cervical plexus

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B-nerves

*Roots and trunks of the brachial plexus

1. Supraclavicular nerve2. Suprascapular nerve3. Dorsal scapular nerve 4. Long thoracic nerve5. Nerve to subclavius

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arteries-Transverse cervical vessels-Suprascapular vessels-Subclavian artery crossing the first rib

veinsExternal jugular vein

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Platysma muscleOrigin deep fascia that covers the pec major and deltoid ms

Insertioninto the lower border of the mandible some fibers to the Face which blend with the muscle at the angle of the mouth Nerve supplycervical branch of facial nerve Action-depresses the mandible -draws down the lower lip

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Omohyoid muscle:Origin

Inferior bellyupper margin of the scapula medialto suprascapular lig.

Superior bellylower border of body of hyoid bone

Insertionintermediate tendon ( clavicle and 1st rib by facial sling)

Nerve supplyAnsa Cervicalis (C1,2 and 3)

Action depresses hyoid bone

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Sternocliedomastoid(SCM)

Originmanubrium and medial 1/3 of the clavicle(sternal head and Clavicular head))

Insertionmastoid 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

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What is torticollis?What is torticollis? Torticollis (wry neck) is a congenital or acquired condition of Torticollis (wry neck) is a congenital or acquired condition of

limited neck motion in which the child will hold the head to one limited neck motion in which the child will hold the head to one side with the chin pointing to the opposite side. side with the chin pointing to the opposite side.

It is the result of the shortening of the sternocleidomastoid It is the result of the shortening of the sternocleidomastoid (neck) muscle.(neck) muscle.

In early infancy, a firm, non-tender mass may be felt in the In early infancy, a firm, non-tender mass may be felt in the

midportion of the muscle. The mass will go away and be midportion of the muscle. The mass will go away and be replaced with fibrous tissue. replaced with fibrous tissue.

If untreated, there can be permanent limitation of neck If untreated, there can be permanent limitation of neck movement. There may be flattening of the head and face on movement. There may be flattening of the head and face on the affected side.the affected side.

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-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.

The veins:

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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

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Tributaries of EJV

. Posterior auricular vein

. Post.division of the Retromandibular vein. transverse cervical vein, . suprascapular vein. anterior jug.vein

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*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

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The brachial plexus and subclavian artery may The brachial plexus and subclavian artery may be compressed in the neck by be compressed in the neck by

a rudimentary cervical rib a rudimentary cervical rib a tight fibrous banda tight fibrous band first thoracic ribfirst thoracic rib a tight scalenus anterior musclea tight scalenus anterior muscle

giving rise to sensory, giving rise to sensory, motor motor vascular symptoms vascular symptoms in one or both upper extremities.in one or both upper extremities.

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cervical ribcervical rib

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

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Nerves:

A-The Accessory nerve

B-The branches of the Cervical Plexus

C-The Roots and the Trunks of the Brachial Plexus

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Nerves:

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What structures are contained within the What structures are contained within the posterior triangle of the neck?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? )