Accessory(xi)

The Accessory nerve, also known as cranial nerve XI or the eleventh cranial nerve, is one of the twelve cranial nerves in the human body. It is a motor nerve that is responsible for controlling the muscles of the neck and shoulder. The accessory nerve arises from the medulla oblongata and the upper spinal cord and exits the skull through the jugular foramen, a large opening in the skull located behind the carotid canal. After exiting the skull, the nerve divides into two branches: the spinal accessory nerve and the cranial accessory nerve. The spinal accessory nerve controls the sternocleidomastoid and trapezius muscles of the neck, which are important for movements such as turning the head and shrugging the shoulders. The cranial accessory nerve, on the other hand, supplies fibers to the vagus nerve, which is responsible for controlling the muscles involved in speech and swallowing. Damage to the accessory nerve can result in weakness or paralysis of the muscles it controls, leading to difficulty in performing movements such as shrugging the shoulders or turning the head. This can be caused by trauma, tumors, infections, or other neurological disorders.

This nerve arises from the Spinial Cord.