ORIGIN: External occipital protuberance, superior nuchal line, ligamentum nuchae, and from the spines of all thoracic vertebrae and C7.

 

INSERTION: Lateral 1/3 of clavicle, spine of scapula and outer lip of acromion.

 

ACTION: Adductor of scapula, and rotator of the glenoid cavity

 

NERVE: Spinal accessory, C3 and 4 nerve

Action video