The iliocostalis is a deep muscle of the back. It is located laterally within the erector spinae muscle complex and can be divided into three parts – lumborum, thoracis, and cervicis.
- Attachments: Arises from the lower thoracic and lumbar vertebrae, sacrum, posterior aspect of the iliac crest, and the sacroiliac and supraspinous ligaments. It attaches to the costal angle of the ribs and the cervical transverse processes.
- Action: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.
- Innervation: Posterior rami of the spinal nerves.
- Blood Supply:
- Iliocostalis cervicis is supplied by the occipital, deep cervical, and vertebral arteries.
- Iliocostalis thoracis is supplied by dorsal branches of posterior intercostal and subcostal arteries.
- Iliocostalis lumborum is supplied by dorsal branches of lumbar and sacral arteries.