The spinal accessory nucleus is involved in the movement of which body parts?

The spinal accessory nucleus, located in the upper cervical spinal cord (particularly in the gray matter of segments C1 to C5), plays a crucial role in motor control, specifically targeting the movements of the head and shoulders. The primary function of the spinal accessory nerve, which arises from this nucleus, is to innervate the sternocleidomastoid and trapezius muscles.

The sternocleidomastoid muscle is responsible for head rotation and flexion, while the trapezius muscle elevates the shoulders and helps in shoulder movement as well as scapular stabilization. This is why the correct response identifies the involvement of these particular body areas in movement, highlighting the spinal accessory nucleus’s significance in coordinating head and shoulder actions.

Understanding this function is essential in neuroanatomy, as it illustrates how specific nuclei correspond to distinct motor activities associated with different muscle groups in the body.