Where does the iliocostalis muscle insert?

The iliocostalis muscle is part of the erector spinae group and plays a critical role in maintaining posture and facilitating movement of the vertebral column. The muscle originates from the sacrum, iliac crest, and lower ribs, and its insertion points are specifically designed to assist in its function.

The correct answer indicates that the iliocostalis muscle inserts at the angles of the lower ribs and the cervical transverse processes. This insertion allows the muscle to effectively contribute to the extension and lateral flexion of the spine, as well as aiding in the stabilization of the thoracic region. The angles of the lower ribs serve as leverage points for the muscle, while its attachments to the cervical transverse processes contribute to neck movements.

In contrast, the other options do not accurately reflect where the iliocostalis muscle attaches. Although the muscle has multiple contact points along the spine, it does not insert on the transverse processes of thoracic vertebrae, on the costal cartilages of ribs, or at the superior borders of the sacrum, which are related to different muscles or anatomical functions. Thus, identifying the proper insertion points, as indicated in the correct choice, helps clarify the role and functionality of the iliocostalis