Posterior Cervical Triangle Muscles

Sternocleidomastoid

Anterior Border

Sternocleidomastoid Insertion

Lateral surface of mastoid process of temporal bone

Lateral half of superior nuchal line

Sternocleidomastoid Origin

Sternal head: anterior surface of manubrium

Clavicular head: superior surface of medial third of clavicle

Sternocleidomastoid Innervation

Spinal accessory nerve

C2 and C3 ventral rami

Sternocleidomastoid Action

Unilaterally: tilts head to same side (ipsilateral) and rotates it so face is turned superiorly toward opposite side (contralateral)

Bilaterally: extends neck at atlantooccipital joints, (2) flexes cervical vertebrae so that chin approaches manubrium, or (3) extends superior cervical vertebrae while flexing inferior vertebrae so chin is thrust forward with head kept level

Upper Trapezius

Posterior Border

Trapezius Origin

Nuchal ligament

Medial third of superior nuchal line

External occipital protuberance

Spinous processes of C7-T12

Trapezius Insertion

Lateral third of clavicle

Acromion and spine of scapula

Trapezius Innervation

Spinal accessory nerve

C3-C4 vental rami

Trapezius Action

Superior - elevates scapula

Inferior - depresses scapula

Middle - retracts scapula

ALL - superiorly rotate glenoid cavity

Anterior scalene, Middle scalene, Posterior scalene, Levator scapulae, Splenius capitis

Floor

Anterior scalene Origin

Anterior tubercle of transverse process of C3-6

Anterior scalene Insertion

1st rib

Anterior Scalene Innervation

C4–C6 ventral rami

Anterior Scalene Action

Forced inspiration, elevates 1st rib

Middle scalene Origin

Posterior tubercle of transverse processes of C4-C7

Middle scalene Insertion

Superior surface of 1st rib posterior to groove for subclavian artery

Middle Scalene Innervation

Anterior rami of cervical spinal nerves

Middle Scalene Action

Flexes neck laterally

Forced inspiration, elevates 1st rib

Posteror scalene Origin

Posterior tubercles of transverse processes of C4-C6

Posteror scalene Insertion

External border to 2nd rib

Posterior Scalene Innervation

Anterior rami of cervical spinal nerves C7 and C8

Posterior Scalene Action

Flexes neck laterally

Elevates 2nd rib during forced inspiration

Levator scapulae Origin

Posterior tubercle of transverse processes of C1-C4

Levator scapulae Insertion

Superior portion of medial border of scapula

Levator scapulae Innvervation

Dorsal scapular nerve (C4,C5)

C3-C4 ventral rami

Levator scapulae Action

Elevate scapula and rotate glenohumeral cavity inferiorly

Splenius capitis Origin

Nuchal ligament

Spinous process of C7-T6

Splenius captitis Insertion

Mastoid process

Lateral third of superior nuchal line

Splenius capitis Inneration

Dorsal rami

Splenius capitis Action

Unilaterally (ipsilateral): lateral flexion of head and neck and rotation to side of active muscle

Bilaterally: extend head and neck