General Sensory

Overview

This component of CN X carries general sensory information (pain, temperature, and touch) from the skin of the back of the ear and external auditory meatus, parts of the external surface of the tympanic membrane, and the from the larynx and pharynx.

Peripheral Course

Sensory fibers from the external ear, external auditory canal, and external surface of the tympanic membrane are carried via the auricular branch of CN X. These fibers pass into the jugular foramen and enter the superior vagal ganglion where their cell bodies reside.

General sensory information from the larynx and pharynx travels in the recurrent laryngeal and internal laryngeal nerves which join and ascend into the jugular foramen with the vagus nerve. The cell bodies of these neurons reside in the inferior vagal ganglion.

Central Course

The central processes of the general sensory neurons exit the vagal ganglia and pass through the jugular foramen to enter the brainstem at the level of the medulla.

Upon entering the medulla these fibers descend in the spinal trigeminal tract and synapse in the spinal nucleus of the trigeminal.

Ascending secondary neurons originating from the spinal nucleus of CN V project to the contralateral ventral posteromedial (VPM) nucleus of the thalamus via the anterolateral system (ventral trigeminothalamic tract).

Tertiary neurons from the thalamus project via the posterior limb of the internal capsule to the sensory cortex of the post-central gyrus.

Clinical Correlation

Stimulation of the fibers of the auricular nerve in the external auditory meatus can cause coughing and/or vomiting by reflex activation of the visceral motor component of the vagus nerve via the reticulobulbar pathway.