Anatomy

Origin

Iliocostalis Cervicis: Angles of third through sixth ribs Iliocostalis Thoracis: Angles of lower six ribs medial to iliocostalis lumborum Iliocostalis Lumborum: Medial and lateral sacral crests and medial part of iliac crests

Insertion

It rises to the occipital bone with:

• Iliocostalis Lumborum that reaches the lower margins of the last 6 ribs,
• Iliocostalis Thoracis that reaches the first 6 ribs,
• Iliocostalis Cervicis that reaches the posterior tubercles of transverse processes of last 4 or 5 cervical vertebrae.

Nerve

It is an intrinsic spine muscle and all its divisions are innervated by dorsal spinal nerves.

Actions

Extension, lateral flexion of vertebral column. Thoracic and cervical part rotate ribs for forceful inspiration