The spinalis is a deep muscle of the back. It is the smallest of the muscle columns within the erector spinae complex, and can be divided into the three parts – thoracic, cervicis and capitis (although the cervicis part is absent in some individuals).
- Attachments: Arises from the lower thoracic and lumbar vertebrae, sacrum, posterior aspect of the iliac crest, and the sacroiliac and supraspinous ligament. It attaches to the spinous processes of C2, T1-T8 and the occipital bone of the skull.
- Actions: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and
- Innervation: Posterior rami of the spinal nerves.
- Blood Supply: Muscular branches of vertebral artery, deep cervical artery, and posterior branch of posterior intercostal artery