Lab 9 - Descending Pathways to the Spinal Cord

Vestibulospinal Pathways - Pons

Figure 1 is a transverse section through the caudal pons. The fibers of the lateral vestibulospinal tract arise from the lateral vestibular nucleus and descend through the brain stem along the anterior surface of the vestibular nuclear complex. The lateral vestibular nucleus is located posterior to the spinal trigeminal tract and nucleus. It receives axons of the vestibular nerve and axons from the cerebellum. The abducens nucleus marks the rostral extent of the lateral vestibular nucleus.

Figure 2 is a transverse section at the pontomedullary junction. Axons of the lateral vestibular nucleus, located in the gray matter near the posteromedial border of the inferior cerebellar peduncle, continue to join the lateral vestibulospinal tract. These axons remain uncrossed and pass caudally along the anterior margin of the nucleus. The medial vestibular nucleus gives rise to a small group of fibers (the medial vestibulospinal tract) that joins the ipsilateral medial longitudinal fasciculus. The vestibular nuclear complex receives input from the vestibular nerve, cerebellum, and the contralateral vestibular nuclear complex.