Its the 11th of the 12cranial nervesand is often referred to as CN XI.
One part originates in the brain and the other originates in the spine.
For this reason, its often called the spinal accessory nerve.
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Anatomy
All of the nerves in your body stem from either the brain or the spinal cord.
They begin with whats called a nerve root.
Fibers from multiple nerve roots can combine to form a single nerve.
Each nerve is actually a roughly symmetrical pair of nerves with one on each side of your spine.
Theyre not together for long, though.
Before they leave the jugular foramen, they split apart again.
The cranial component then joins thevagus nerveand follows it along its course in the throat.
Its often referred to as the internal branch of the accessory nerve.
The accessory nerve sends fibers to the:
Thespinal component, meanwhile, continues as the exterior branch.
It moves downward along the internal carotid artery to pierce and innervate the SCM.
The trapezius is a large, triangular muscle.
Those structures in the head and throat are involved in eating, speaking, and breathing.
Thesoft palateis just behind the roof of your mouth.
It raises up to close off the airway and block the nasal passages when you swallow or suck.
Thepharynxis a cone-shaped cavity behind your nose and mouth.
Its muscles contract to:
Thelarynx, or voice box, holds your vocal cords.
Its a tube-like structure that attaches to the trachea (windpipe).
When you breathe, air passes through the larynx before reaching the lungs.
Spinal Region
The spinal portion of the accessory nerve also innervates important muscles.
Without a functional SCM and trapezius, the movement of your upper body would be severely limited.
Thesternocleidomastoid muscleis essential for neck movement.
However, its an extremely large muscle and the scapula requires multiple types of motion.
The specific result depends on the location of the damage.
The path of the nerves spinal (external) portion makes it especially prone to injury.
Certain problems with the accessory nerve can be repaired this way.
Conversely, portions of the accessory nerve are sometimes used to repair other nerves.
Albahout KS, Waheed A.Anatomy, head and neck, pharynx.
Suarez-Quintanilla J, Fernandez Cabrera A, Sharma S.Anatomy, head and neck, larynx.
Bordoni B, Varacallo M.Anatomy, head and neck, sternocleidomastoid muscle.
Ourieff J, Agarwal A.Anatomy, back, trapezius.
AlShareef S, Newton BW.Accessory nerve (CN XI) injury.
Bordoni B, Reed RR, Tadi P, et al.Neuroanatomy, cranial nerve 11 (accessory).
