Visceral Sensory

Overview

This component of CN IX innervates the baroreceptors of the carotid sinus and chemoreceptors of the carotid body.

Peripheral and Intracranial Course

Sensory fibers arise from the carotid sinus and carotid body at the bifurcation of the common carotid artery, ascend in the sinus nerve, and join the other components of CN IX at the inferior hypoglossal ganglion.

The cell bodies of these neurons reside in the inferior ganglion.

The central processes of these neurons enter the skull via the jugular foramen.

Central Course

Once inside the skull, the visceral sensory fibers enter the lateral medulla between the olive and the inferior cerebellar peduncle and descend in the tractus solitarius to synapse in the caudal nucleus solitarius.

From the nucleus solitarius, connections are made with several areas in the reticular formation and hypothalamus to mediate cardiovascular and respiratory reflex responses to changes in blood pressure, and serum concentrations of CO2 and O2.