Posterior Triangle of the Neck

Learning objectives

• At the end of the lecture, the students will be able to:-

1. Describe posterior triangle of neck.2. List the contents of posterior triangle of neck.3. List common applied aspects.

The Neck• The region of the

body that lies between: The lower border

of mandible & The suprasternal

notch and the upper border of the clavicle

Triangles of the Neck

Posterior Triangle of the Neck

Subdivision of the Posterior Triangle

• Subdivided by the inferior belly of omohyoid muscle, into: Large occipital

triangle above Small

supraclavicular triangle below

Boundaries of occipital triangle

• Inferior belly of omohyoid

• Sternomastoid• trapezius

Boundaries of supraclavicular triangle

• Inferior belly of omohyoid

• Stenomastoid • Middle-third of clavicle

Boundaries• Anterior: Posterior border

of sternocleidomastoid• Posterior: Anterior border

of trapezius• Base: Middle third of

clavicle• Apex: superior nuchal line

of the occipital bone between the attachments of the trapezius and sternomastoid.

Platysma m.

Investing layer ofdeep cervical fascia

ROOF OF POSTERIOR TRIANGLE

CUTANEOUS BRANCHES OF THE CERVICAL PLEXUS

Lesser occipital n. (C2,3)

Great auricular n.(C2,3)

Transverse cervical n. (C2,3)

Supraclavicular nn. (C3,4)

CERVICAL PLEXUS

Muscular Floor of the Posterior Triangle

From above downward: Semispinalis capitis Splenius capitis Levator scapulae Scalenus medius Scalenus anterior may

or may not be present

Contents• Arteries:

Subclavian (3rd part) Superficial cervical &

suprascapular (branches of thyrocervical trunk, a branch of 1st part of subclavian artery

Occipital, a branch of external carotid artery

• Veins:• External jugular vein

Formation Termination

• Veins:• External jugular

vein Tributaries

• Nerves: Branches of

cervical plexus

Spinal part of accessory nerve

Brachial plexus

Sternocleidomastoid• Origin: Upper part of

manubrium & medial third of clavicle

• Insertion: Mastoid process & lateral part of superior nuchal line

• Nerve supply: Spinal part of accessory nerve (motor)

Sternocleidomastoid• Action:

• Both muscles acting together extend head at atlanto-occipital joint, and flex cervical part of vertebral column

• Contraction of one muscle moves the face to the opposite side

Trapezius

• Origin- medial third of superior nuchal line, external occipital protuberence, ligamentum nuchae, spine of seventh cervical vertebra and spines of all thoracic vertebrae.

Trapezius

• Insertion- upper fibers insert into the posterior aspects of lateral third of clavicle.

• Middle fibers insert into medial aspects of acromian and crest of the spine of scapula.

• Lower fibers insert into the crest of scapula.

Trapezius

• Action-Upper fibers elevate the scapula along with levator scapulae.

• Middle fibers cause retraction of scapula along with rhomboids.

• Lower fibers depresses and medially rotates the scapula.

Trapezius

• Nerve supply: Spinal part of accessory nerve (motor)

Omohyoid Muscle• Two bellies: Superior & Inferior

joined by intermediate tendon• Attachement: Superior belly to

inferior border of hyoid bone, Inferior belly to superior border of scapula & suprascapular ligament

• The Intermediate tendon lies deep to sternocleidomastoid

• Nerve supply: Ansa cervicalis (C1,2,3)

Superior belly

Intermediate tendon

Inferior belly

Action: Depresses the hyoid bone

Clinical Notes• Torticollis (wry neck):

Congenital: due to excessive stretching of sternocleidomastoid muscle during labor.

• Injury to spinal part of accessory nerve

• Injury to brachial plexus• Injury to nerve to platysma