Anatomy
Summary
Cranial nerve XI, known as the accessory nerve, has both a cranial root and a spinal root. The spinal root begins in the spinal cord and enters the skull through the foramen magnum. Once in the cranium, the spinal root joins with the cranial root from the nucleus ambiguus in the medulla. They exit the skull through the jugular foramen along with cranial nerves IX and X.
The accessory nerve provides motor innervation to the trapezius and the sternocleidomastoid muscles. Via innervation of the trapezius, the accessory nerve raises or shrugs the ipsilateral shoulder. The sternocleidomastoid, when activated, turns the head to the opposite, or contralateral, side.
Lesson Outline
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FAQs
The accessory nerve, also known as cranial nerve XI, provides motor innervation to the trapezius and the sternocleidomastoid muscles. This facilitates movements like turning the head and shrugging, or raising, the shoulders.
The accessory nerve, or CN XI, has both a cranial and spinal root. The spinal root begins in the spinal cord and enters the skull through the foramen magnum. Once in the cranium, the spinal root joins with the cranial root from the nucleus ambiguus in the medulla.
The accessory nerve, or CN XI, exits the skull through the jugular foramen along with cranial nerves IX and X.
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