Innervation of spinalis cervicis?

• A. Ventral rami of spinal nerves
• B. Cranial nerves
• C. Sacral nerves
• D. Dorsal rami of spinal nerves

Answer: (D)

Spinalis cervicis is an intrinsic back muscle that sits close to the spine and helps extend and stabilize the vertebral column. Intrinsic back muscles receive their nerve supply from the dorsal (posterior) rami of the spinal nerves, which supply the deep layer of muscles along the spine and the overlying skin in the back. At the cervical levels, the cervical dorsal rami carry branches that innervate these deep muscles, including spinalis cervicis. In contrast, ventral rami go to the front and sides of the body (limbs and ventrolateral trunk), cranial nerves innervate muscles of the head and neck that aren’t part of this deep back group, and sacral nerves pertain to the lower back/pelvic region. So the correct innervation is the dorsal rami of the spinal nerves.