The semispinalis capitis is a distinct mass of the semispinalis thoracis and cervicis. It arises between the spinalis thoracis and the longissiums thoracis, and is divided into two parts:
- The biventer cervicis muscle: the dorsomedial division of semispinalis capitis that originates from the thoracolumbar fascia or thoracic vertebral transverse processes, courses superficial to mutifidi muscles to insert on occipital bone.
- The complexus muscle: the ventrolateral division of semispinalis capitis that arises from cervical vertebral articular processes and inserts lateral to the biventercervicis on occipital bone.
Origin: First five thoracic vertebrae and last cervical vertebrae.
Insertion: Occipital ridge.
Action: Raises the head and neck and in unilateral action to flex the head and neck laterally.
Nerve: Dorsal branches of the cervicales.