Iliocostalis insertion is on which structures?

• A. Ribs and transverse processes of cervical vertebrae
• B. Spinous processes of thoracic vertebrae
• C. Mastoid process
• D. Clavicle

Answer: (A)

The question tests where the iliocostalis attaches. This muscle, a lateral component of the erector spinae, runs from the lower spine and pelvis up to the ribs and the transverse processes of the cervical vertebrae. Its distal attachments include the ribs (costal insertions) and the transverse processes of the neck (cervical). That’s why the correct choice points to ribs and cervical transverse processes.

Spinous processes of the thoracic spine would be more typical of other back muscles like the spinalis or longissimus in that region. The mastoid process and the clavicle are attachments for different muscles (such as splenius capitis/sternocleidomastoid and other shoulder/neck muscles), not for the iliocostalis.