Which nerves innervate both splenius capitis and splenius cervicis?

• A. Spinal accessory nerve
• B. Ventral rami of cervical nerves
• C. Dorsal rami of cervical nerves
• D. Dorsal rami of thoracic nerves

Answer: (C)

The splenius capitis and splenius cervicis are intrinsic back muscles in the neck that receive motor innervation from the dorsal rami of the cervical spinal nerves. These posterior primary rami supply the deep back muscles, including the splenius group, enabling actions like neck extension and ipsilateral rotation. Explanations for the other options: the spinal accessory nerve innervates the trapezius and sternocleidomastoid, not the splenius muscles. The ventral rami of cervical nerves mainly supply the anterior neck muscles and limbs, not these dorsal deep neck muscles. The dorsal rami of thoracic nerves innervate thoracic back muscles, not the cervical splenius muscles.