Glossopharyngeal nerve in the context of "Progressive bulbar palsy"

A mixed nerve is any nerve that contains both sensory (afferent) and motor (efferent) nerve fibers. All 31 pairs of spinal nerves are mixed nerves. Four of the twelve cranial nerves – V, VII, IX and X are mixed nerves.

Special visceral afferent fibers (SVA) are afferent fibers that develop in association with the gastrointestinal tract. They carry the special sense of taste (gustation). The cranial nerves containing SVA fibers are the facial nerve (VII), the glossopharyngeal nerve (IX), and the vagus nerve (X). The facial nerve receives taste from the anterior 2/3 of the tongue; the glossopharyngeal from the posterior 1/3, and the vagus nerve from the epiglottis. The sensory processes, using their primary cell bodies from the inferior ganglion, send projections to the medulla, from which they travel in the tractus solitarius, later terminating at the rostral nucleus solitarius.

The solitary nucleus (SN) (nucleus of the solitary tract, nucleus solitarius, or nucleus tractus solitarii) is a series of neurons whose cell bodies form a roughly vertical column of grey matter in the medulla oblongata of the brainstem. Their axons form the bulk of the enclosed solitary tract. The solitary nucleus can be divided into different parts including dorsomedial, dorsolateral, and ventrolateral subnuclei.

The solitary nucleus receives general visceral and special visceral inputs from the facial nerve (CN VII), glossopharyngeal nerve (CN IX) and vagus nerve (CN X); it receives and relays stimuli related to taste and visceral sensation. It sends outputs to various parts of the brain, such as the hypothalamus, thalamus, and reticular formation, forming circuits that contribute to autonomic regulation.