VPB 121: Veterinary Physiology - II (2+1)

GUSTATORY PATHWAY

• Taste impulses from the anterior two third of the tongue pass through chorda tympani branch of the facial nerve‚ thence to nuclei tractus solitarius of the brain stem, while the posterior one-third sends the taste sensations through the glossopharyngeal nerve to nuclei tractus solitarius. Vagus receives the sensory inputs from the base of the tongue and other parts of the pharyngeal region.

• Thalamic area adjacent to ventrobasal complex receives the second order neurons from the nuclei tractus solitarius. The third order neurons originate from the thalamus to the lower tip of the post central gyrus in the parietal cortex, the gustatory cortex. Some of the third order neurons also project to the nearby opercular - insular area‚ located deep in the sylvian fissure.

Taste reflex

• Tractus solitarius transmits impulses to the superior‚ and the inferior salivatory nuclei‚ thus reflexly regulates the secretions of the submandibular, sublingual and the parotid glands.