The accessory nerve is a cranial nerve that controls certain neck muscles. It is coiled in appearance. It is divided into spinal and cranial parts, but its cranial part is often disregarded. The spinal accessory nerve provides the sternocleidomastoid and trapezius neck muscles with motor function. Research on the accessory nerve has determined it is similar in morphological data to the phrenic nerve. The minimal distance between these nerves is (3.19 +/- 1.23) centimeters and the maximal distance between the beginning of the accessory nerve and the phrenic nerve's end above the clavicle is (8.71 +/- 0.75) centimeters. Thus, the accessory nerve is similar to the phrenic nerve in the amount of motor nerve fibers it has. They are also both long enough to connect as needed, without strain. Dysfunction of the spinal accessory nerve can negatively affect the shoulder girdle's performance. Accessory nerve palsy is one complication that most often occurs after surgery has been performed on the neck's posterior triangle. Additionally, there are three types of accessory nerve schwannoma tumors that occur in some people: intracisternal, spinal canal, and intrajugular; they can be removed by a suboccipital approach.
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In Depth: Accessory nerve