Accessory nerve

Common card · No. 358975

The accessory nerve, also known as the eleventh cranial nerve, cranial nerve XI, or simply CN XI, is a cranial nerve that supplies the sternocleidomastoid and trapezius muscles. It is classified as the eleventh of twelve pairs of cranial nerves because part of it was formerly believed to originate in the brain. The sternocleidomastoid muscle tilts and rotates the head, whereas the trapezius muscle, connecting to the scapula, acts to shrug the shoulder. Traditional descriptions of the accessory nerve divide it into a spinal part and a cranial part. The cranial component rapidly joins the vagus nerve, and there is ongoing debate about whether the cranial part should be considered part of the accessory nerve proper. Consequently, the term "accessory nerve" usually refers only to the nerve supplying the sternocleidomastoid and trapezius muscles, also called the spinal accessory nerve. Strength testing of these muscles can be measured during a neurological examination to assess function of the...

Read on Wikipedia · Image Brain_human_normal_inferior_view.svg: Patrick J. Lynch, medical illustrator derivative work: Beao, CC BY 2.5