Muscle · Thoracic spine

Iliocostalis thoracis

Musculus iliocostalis thoracis

The rib-to-rib section of the outermost erector spinae column. Unlike its lumbar neighbour, which anchors to the pelvis, this part runs entirely between ribs: it takes hold of the angles of the lower six and carries the pull up to the angles of the upper six and the transverse process of the seventh cervical vertebra. It is the most lateral of the back extensors, so it has the best leverage of the three for bending the trunk sideways — and, taking hold of ribs at both ends rather than vertebrae, it is the one erector column whose pull reaches the spine through the rib cage.