Lab 6 - Auditory, Vestibular, Gustatory and Olfaction Systems

Central Vestibular Pathway - Pons

View and identify the structures in the illustration.

In Figure 1, layer a notice that the inferior cerebellar peduncles are not clearly visible in this section and that the superior vestibular nucleus and the lateral vestibular nucleus now form the vestibular (sensory) area lateral to the sulcus limitans. The superior vestibular nucleus sends most of its axons into the medial longitudinal fasciculus to extraocular motor nuclei. Some 2° vestibular afferents appear to travel along with the medial longitudinal fasciculus, and others travel with the lateral lemniscus to the thalamus.

Figure 1, layer b marks the rostral limit of the vestibular nuclear complex. Only the rostral pole of the superior vestibular nucleus is present at this level. The 2° vestibular afferents ascend in two bundles, one with the medial longitudinal fasciculus and one with the lateral lemniscus.

Figure 1, layer c the 2° vestibular afferents ascend along with the medial longitudinal fasciculus and the lateral lemniscus. Some MLF fibers terminate in the trochlear nucleus, which participates in driving eye movements. Recall that the vestibular nuclei (superior and medial, predominantly) send axons in the medial longitudinal fasciculus to the extraocular motor nuclei and are involved in reflex adjustments of eye position to compensate for changes in head position.