The iliocostal muscle is a slim, elongated muscle, which is composed of a series of overlapping fascicles. Its fibers are orientated in a cranioventral direction and span several vertebral segments.
Topographically, the ilioscostal muscle can be divided into a lumbar part (iliocostal lumborum in the NAV), a thoracic part (iliocostal thoracis in the NAV) and a cervical part (iliocostal cervicis in the NAV).
Origin: Crest of the ilium, transverse processes of the lumbar vertebrae and the fascial sheet ("Bogorozky tendon") which separates the iliocostal muscles from the longissimus.
Insertion: One common tendon of insertion on the last cervical vertebra
Action: Bends the vertebral column sideways
Nerve: Dorsal branches of the thoracic and lumbar nerves