Is spinal accessory nerve a cranial nerve?

The spinal accessory nerve is the eleventh cranial nerve. It is a motor nerve (somatic motor) innervating two muscles—the sternocleidomastoid and trapezius. It has two components—a spinal part and a cranial part. The cranial part of the accessory nerve is from the vagus nerve.

What is the function of the spinal accessory nerve?

The accessory nerve provides motor function (movement) to two muscles essential to neck and shoulder movement, the sternocleidomastoid (SCM) and the trapezius, as well as to the larynx (voice box) and other structures in the throat.

Where does the spinal accessory nerve come from?

The spinal accessory nerve originates from neuronal cell bodies located in the cervical spinal cord and caudal medulla. Most are located in the spinal cord and ascend through the foramen magnum and exit the cranium through the jugular foramen.

What are the two branches of the accessory nerve?

Most texts will still refer to the accessory nerve as having two components. The fibers arising from the intracranial component is known as the cranial accessory nerve, while those fibers arising from the spinal nucleus are called the spinal accessory nerve.

Why are accessory nerves referred to as spinal accessory nerves?

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 is vagus nerve?

The vagus nerve carries an extensive range of signals from digestive system and organs to the brain and vice versa. It is the tenth cranial nerve, extending from its origin in the brainstem through the neck and the thorax down to the abdomen.

How does the accessory nerve differ from the other cranial nerves?

Different from the other cranial nerves, each accessory nerve has some motor fibers originating in the lateral area of the anterior gray horns of the first five cervical spinal cord segments. The fibers then join motor fibers of the cranial root, originating at a nucleus of the medulla.

How do you find the spinal accessory nerve?

The main identification point of the nerve is in the posterior triangle, behind the posterior edge of the sternocleidomastoid muscle at Erb’s point, which is defined by the exit of the greater auricular nerve from behind the sternocleidomastoid muscle.

What type of nerve is the vagus nerve?

vagus nerve, also called X cranial nerve or 10th cranial nerve, longest and most complex of the cranial nerves. The vagus nerve runs from the brain through the face and thorax to the abdomen. It is a mixed nerve that contains parasympathetic fibres.

What and where is the vagus nerve?

Is the vagus nerve parasympathetic or sympathetic?

The vagus nerve (VN) is the longest nerve of the organism and a major component of the parasympathetic nervous system which constitutes the autonomic nervous system (ANS), with the sympathetic nervous system.

What happens if the spinal accessory nerve is damaged?

Spinal Accessory Nerve. 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.