What is an accessory nerve?

What is an accessory nerve?

The accessory nerve is the eleventh paired cranial nerve. It has a purely somatic motor function, innervating the sternocleidomastoid and trapezius muscles. In this article, the anatomical course, motor functions and clinical relevance of the nerve will be examined.

What are the spinal accessory nerve?

The spinal accessory nerve originates in the brain and enables motion in the trapezius and sternomastoid muscles in the neck. A spinal accessory nerve injury can be caused by trauma or damage during surgery, resulting in shoulder pain, “winging” of the shoulder blades and weakness of the trapezius muscle.

Which is a function of the accessory XI nerve?

This nerve supplies the sternocleidomastoid and trapezius muscles, which have the following functions: Rotation of head away from the side of the contracting sternocleidomastoid muscle. Tilting of the head toward the contracting sternocleidomastoid muscle. Flexion of the neck by both sternocleidomastoid muscles.

What is the meaning of spinal root of accessory nerve?

The spinal root of accessory nerve (or part) is firm in texture, and its fibers arise from the motor cells in the lateral part of the anterior column of the gray substance of the medulla spinalis as low as the fifth cervical nerve.

Why accessory nerve is called so?

The sternocleidomastoid muscle tilts and rotates the head, while the trapezius muscle, connecting to the scapula, acts to shrug the shoulder. Consequently, the term “accessory nerve” usually refers only to nerve supplying the sternocleidomastoid and trapezius muscles, also called the spinal accessory nerve.

What happens if the accessory nerve is damaged?

Injury to the spinal accessory nerve not only results in debilitating trapezius dysfunction, but can also result in chronic pain and debilitation with prolonged shoulder girdle dysfunction. It usually presents after diagnostic lymph node biopsies of the posterior triangle of the neck, with an incidence of 3% to 8%.

How do you treat accessory nerves?

The treatment of spinal accessory nerve palsy includes physical therapy as the main conservative or non-surgical component. For patients not responding to the conservative methods, surgery is considered for them. Surgical options comprise nerve surgery, nerve grafting, and nerve regeneration.

Why is the accessory nerve unique?

The spinal accessory nerve is notable for being the only cranial nerve to both enter and exit the skull. This is due to it being unique among the cranial nerves in having neurons in the spinal cord.

Where does the accessory nerve originate?

spinal cord
The primary function of the accessory nerves (XI) is motor, to the muscles of the neck and upper back. These nerves originate in the motor nuclei of the spinal cord and medulla. They pass through the jugular foramina, between the occipital and temporal bones.

What are the branches of accessory nerve?

The accessory nerve consists of a cranial and a spinal root. The nucleus of the cranial root is found in the nucleus ambiguus of the medulla. It receives corticobulbar fibers from both cerebral hemispheres. These fibers then join the glossopharyngeal nerve, the vagus nerve, and the spinal accessory nerve.

Does the accessory nerve have branches?

The nerve passes through the jugular foramen and then divides variably into the 2 original components. The superior branch, also known as the accessory or internal branch, joins the vagus either directly or through the ganglion nodosum and then contributes to the pharyngeal, laryngeal, and cardiac sympathetic fibers.

What is the origin of the accessory nerve?

The accessory nerve originates from neurons in the medulla and in the cervical spinal cord. It has a cranial root, which joins the vagus (10th cranial) nerve and sends motor fibers to the muscles of the larynx, and a spinal root, which sends motor fibers to the trapezius and…

Is the accesory nerve cranial and spinal?

The accessory nerve is a spinal nerve that supplies the sternocleidomastoid and trapezius muscles. It is considered the eleventh of twelve pairs of cranial nerves , or simply cranial nerve XI, as part of it was formerly believed to originate in the brain.

What is the right accessory nerve?

The accessory nerve is a cranial nerve that supplies the sternocleidomastoid and trapezius muscles. It is considered the eleventh of twelve pairs of cranial nerves, or simply cranial nerve XI , as part of it was formerly believed to originate in the brain.

What is accessory nerve disorder?

Accessory nerve disorder. Accessory nerve disorder is an injury to the spinal accessory nerve which results in diminished or absent function of the sternocleidomastoid muscle and upper portion of the trapezius muscle.