Lab 10 - Cranial Nerve Nuclei and Brain Stem Circulation

Review-The Gustatory Components

The rostral portion of the nucleus solitarius receives the terminals of gustatory afferent fibers of the vagus, glossopharyngeal and facial nerves. The gustatory fibers of the vagus (X) nerve innervate taste buds in the epiglottis and ascend in the solitary tract to end in the rostral (gustatory) portion of nucleus solitarius. The gustatory fibers of theglossopharyngeal (IX) nerve innervate taste buds in the posterior third of the tongue and the pharynx and ascend in the solitary tract to end in the gustatory portion of nucleus solitarius. The gustatory fibers of the facial (VII) nerve innervate taste buds in the anterior two-thirds of the tongue and the palate and end in the gustatory portion of nucleus solitarius.

Gustatory Sensations in Cranial Nerve VII and IX is rarely tested, but may be assessed by testing anterior tongue for sweet with sugar water, sour with citric acid, and salty with saline. Test posterior tongue for bitter with a quinine solution.