Glossopharyngeal Nerve - Overview of Special Sensory Component

Overview of Special Sensory Component

The special sensory component of CN IX provides taste sensation from the posterior one-third of the tongue.

Peripheral course

Special sensory fibers from the posterior one-third of the tongue travel via the pharyngeal branches of CN IX to the inferior glossopharyngeal ganglion where their cell bodies reside.

Central course - special sensory component

The central processes of these neurons exit the inferior ganglion and pass through the jugular foramen to enter the brainstem at the level of the rostral medulla between the olive and inferior cerebellar peduncle. Upon entering the medulla, these fibers ascend in the tractus solitarius and synapse in the caudal nucleus solitarius. Taste fibers from CN VII and X also ascend and synapse here. Ascending secondary neurons originating in nucleus solitarius project bilaterally to the ventral posteromedial (VPM) nuclei of the thalamus via the central tegmental tract. Tertiary neurons from the thalamus project via the posterior limb of the internal capsule to the inferior one-third of the primary sensory cortex (the gustatory cortex of the parietal lobe).