CRANIAL NERVE X: VAGUS NERVE

Type of Innervation:

1. BRANCHIAL MOTOR (SVE): All muscles of the larynx, pharynx, and palate, EXCEPT the Stylopharyngeus (IX) and Tensor Palati (V3).

• In this role, the Vagus is "stealing" some of the innervation from the Spinal Accessory (XI). Hence in this case the Vagus is actually innervating striated rather than smooth muscle.

2. VISCERAL MOTOR (GVE): Parasympathetics to the Thoracic and Abdominal viscera.

• The Vagus serves no Parasympathetic function in the head and neck region -- only the thorax and abdomen.

3. VISCERAL SENSORY (GVA): Sensory info from tongue, pharynx and larynx, heart and lungs, CAROTID SINUS (along with CN IX), stomach and intestine.
4. GENERAL SENSORY (GSA): General sensory from larynx, pharynx, and a small portion of the outer ear and tympanic membrane.

• General Sensory innervation may include the eardrum itself. These individuals may elicit a gag reflex when cleaning their ears -- due to sensory response from the Vagus!

5. SPECIAL SENSORY (SVA): Maybe a few taste buds carry taste information via the Vagus.

TACHYCARDIA:

To treat a racing heart rate, you can give the patient a Carotid Body Massage, at the bifurcation of the Carotids, in attempt to stimulate the visceral sensory components of the Vagus and Glossopharyngeal, to try to slow heart rate by increasing the Vagal stimulation of the heart.

UNILATERAL LESIONS OF THE VAGUS: Lesions of the vagus lead to the following symptoms.

1. Hoarseness, due to lost laryngeal function on the affected side.
2. Difficulty Swallowing, due to inability to elevate the soft palate on the affected side. This also makes the soft palate droop on that side.
3. The uvula tends to deviate toward the unaffected (intact) side, due to droop of the soft palate on the affected side.
• If the uvula deviates toward the left, then damage is to the right Vagus nerve.

SUPERIOR VAGUS GANGLION: It is within the Jugular Foramen. It houses somatic sensory cell bodies of the Vagus nerve.

Category: Anatomy Notes