Innervation: Splenius cervicis is innervated by dorsal rami of which nerves?

• A. Dorsal rami of the lower cervical nerves (C5-C7)
• B. Dorsal rami of spinal nerves
• C. Ventromedial rami of cervical nerves
• D. Sympathetic trunk

Answer: (A)

Innervation patterns for deep neck muscles come from the dorsal rami of the spinal nerves, not from ventral rami or autonomic trunks. The splenius cervicis, a deep neck muscle that helps extend, rotate, and laterally flex the head and neck, receives motor fibers specifically from the dorsal rami of the lower cervical nerves. In this region, the nerve roots that typically contribute are C5 to C7, aligning with the muscle’s location and function in the lower cervical area. This makes the dorsal rami of the lower cervical nerves the correct source of its innervation. The other options don’t fit because the dorsal rami of all spinal nerves would be too broad, ventromedial rami aren’t a standard supply for this muscle, and the sympathetic trunk provides autonomic fibers rather than the somatic motor innervation to splenius cervicis.