Posterior Triangle of the Neck Dr. Zeenat Zaidi

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

Skin The natural lines of cleavage are constant and run almost horizontally around the neck (an incision along a cleavage line heals as a narrow scar)

Superficial Fascia Thin layer of connective tissue Encloses platysma Contains: cutaneous nerves superficial veins superficial lymph nodes

Cutaneous Nerves Back of the neck: Greater occipital: branch of the posterior ramus of the C2 (C1 has no cutaneous branch) Front & side of neck: Anterior rami of C2-C4 through branches of cervical plexus Lesser occipital C2 Great auricular C2-3 Transverse cutaneous C2-3 Supraclavicular C3-4

Superficial Veins External Jugular Anterior Jugular Formation Course & relations Termination Tributaries

Platysma Origin: Deep fascia covering pectoralis major and deltoid muscles Insertion: Lower margin of the body of mandible Some fibers blending with the muscle at the angle of the mouth (risoreus) Below the chin, fibers interdigitate with the fibers of the opposite muscle Nerve Supply: Cervical branch of the facial nerve Action: Depresses mandible, draws down the lower lip and the angle of mouth

Superficial Lymph Nodes

Deep Cervical Fascia

Triangles of the Neck

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) & ventral rami of C2-3 (proprioceptive) 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

Boundaries Anterior: Posterior border of sternocleidomastoid Posterior: Anterior border of trapezius Inferior: Middle third of clavicle Roof: skin, superficial fascia, platysma, investing layer of deep fascia Floor: muscles covered by prevertebral fascia

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

Subdivision of the Posterior Triangle Subdivided by the inferior belly of omohyoid muscle, into: Large occipital triangle above Small supraclavicular triangle below

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, connected to clavicle & the first rib by a loop of deep fascia Nerve supply: Ansa cervicalis (C1,2,3) Superior belly Intermediate tendon Inferior belly Action: Depresses the hyoid bone

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 Tributaries

Nerves: Branches of cervical plexus Spinal part of accessory nerve Brachial plexus

Clinical Notes Torticollis (wry neck): Congenital: due to excessive stretching of sternocleidomastoid muscle during labor. Spasmodic: usually psychogenic Injury to spinal part of accessory nerve Injury to brachial plexus Pleura & Lung injuries in the root of neck Injury to nerve to platysma

Thank You & Good Luck