Final Answer:
The Spinal Accessory Nerve (CN XI) sends fibers to the sternocleidomastoid and trapezius muscles.
Step-by-step explanation:
The Spinal Accessory Nerve (CN XI) plays a key role in innervating certain muscles, specifically the sternocleidomastoid and trapezius muscles. These muscles are crucial for various movements involving the head, neck, and shoulders.
The sternocleidomastoid muscle is responsible for the rotation of the head to the opposite side and flexion of the neck. In contrast, the trapezius muscle is involved in movements of the shoulder girdle, such as elevation, depression, retraction, and rotation.
The spinal component of the accessory nerve arises from the upper spinal cord segments, contributing fibers that join the cranial component to innervate these muscles. This collaboration between cranial and spinal components of CN XI ensures the coordinated function of the sternocleidomastoid and trapezius muscles, contributing to the overall mobility and stability of the head and shoulders.
In summary, the Spinal Accessory Nerve (CN XI) sends fibers to the sternocleidomastoid and trapezius muscles, facilitating their respective roles in head, neck, and shoulder movements.