Central Vestibular System

Nerve Conduction

Cranial nerve VIII is the vestibulocochlear nerve. The vestibular branch of this nerve connects into the crista ampullares’ hair cells. This nerve conducts the electrochemical impulse to the brainstem.

Vestibular Nuclear Complex 

VNC similar to the CNC, Consists of 4 nuclei: 1.Superior 2.Inferior 3. Medial 4. Lateral 

VNC – Cerebellum

VNC projects fibers to the cerebellum. Cerebellum coordinates motor movement. These VNC to cerebellum connections facilitate the coordinated movements necessary to preserve the body’s balance.

VNC – Eye Movements

VNC projects fibers to nuclei in brainstem that control eye movements. Nuclei include: Abducens nucleus in pons, Trochlear nucleus in midbrain, and Oculomotor nucleus in midbrain. Keep eyes fixed on target while head moves. 

VNC – Nausea

VNC projects to the reticular formation. RF coordinates visceral/autonomic functions. VNC to RF connection involves motion sickness and possible vomiting.

VNC – Spinal Cord & Head/Neck Movements

VNC projects to spinal cord as medial vestibulospinal tracts. Facilitate vestibulocollic reflex is the ability to rotate head in one direction and body in the other.

VNC – Spinal Cord & Arm/Leg Adjustments

VNC also projects descending fibers as lateral vestibulospinal tract. Facilitates vestibulospinal reflex – when bending over, the lifting of one leg to keep oneself balanced