Question

Vagus nerve is a
A. Mixed Xth cranial nerve
B. Mixed XIth cranial nerve
C. Mixed Xth thoracic nerve
D. Sensory Xth cranial nerve

Answer 1

Hint: The vagus nerve, also called pneumogastric nerve is the longest nerve of the autonomic nervous system in the human body and comprises sensory and motor fibers.

Complete answer:
Vagus nerve, also called Xth 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. The vagus nerve has two sensory ganglia: the superior and the inferior ganglia. The vagus also gives off cardiac, esophageal, and pulmonary branches. In the abdomen, the vagus innervates the greater part of the digestive tract and other abdominal viscera.
Upon leaving the medulla oblongata, the vagus nerve extends through the jugular foramen, passes into carotid sheath between the internal carotid artery and the internal jugular vein down to neck, chest, and abdomen, where it contributes to the innervation of the viscera. The right vagus nerve gives rise to the right recurrent laryngeal nerve, which hooks around the right subclavian artery and ascends into the neck. The left vagus nerve enters the thorax between the left common carotid artery and left subclavian artery and descends on the aortic arch. It gives rise to the left recurrent laryngeal nerve, which hooks around the aortic arch to the left of the ligamentum arteriosum and ascends between the trachea and esophagus.

Function:
The vagus also controls a few skeletal muscles, including cricothyroid muscle, levator veli palatini muscle, salpingopharyngeus muscle etc.
Different vagus nerve fibers innervating the pharynx and back of the throat are responsible for the gag reflex.
The vagus nerve also plays a role in satiation following food consumption.

Therefore, the correct option is A, mixed Xth cranial nerve.

Note: Clinical significance:
Vagus nerve stimulation: Vagus nerve stimulation (VNS) therapy using a neurostimulator implanted in the chest is a treatment used to control seizures in epilepsy patients and has been approved for treating drug-resistant cases of clinical depression.
Sensory neuropathy: The hypersensitivity of vagal afferent nerves causes refractory or idiopathic cough.