Muscle: Semispinalis

Proximal Attachment: Arises from transverse processes of C₄-T₁₂ vertebrae

Distal Attachment:

Semispinalis - thoracis, cervicis, capitis; fibers run superomedially to occipital bone and spinous processes in thoracic and cervical regions, spanning 4-6 segments

Innervation: Posterior rami of spinal nerves

Main Action(s): Extends head and thoracic and cervical regions of vertebral column and rotates them contralaterally