Peripheral and Central Vestibular System Anatomy

The vestibular system is a sophisticated network of structures and nerve pathways that play a role in our feeling of proprioception and balance. These functions involve detecting the head’s position and acceleration in all directions and the corresponding eye movements and posture adjustments. The reflexes are known as the vestibulo-ocular and vestibulospinal reflexes. The central vestibular system processes signals from the inner ear’s peripheral vestibular system to enable reflexes through the neural pathways in the brain. The membranous labyrinth is encased by perilymph and hangs from the bony labyrinth by fragile connective tissue strands. The structure includes an anterior chamber and the cochlear duct, which is responsible for hearing and connects to the peripheral vestibular apparatus by the round saccule. The peripheral vestibular system comprises the saccule, utricle, and semicircular canals. Most sensory nerve fibers from the hair cells end in the vestibular nuclei on the bottom of the fourth ventricle. Their boundaries are as follows: medially by the pontine reticular formation, laterally by the restiform body, rostrally by the brachium conjunctivum, and ventrally by the nucleus and spinal tract of the trigeminal nerve. Upon entering the brainstem at the inner aspect of the restiform body, the central processes of the primary afferent vestibular neurons split into an ascending and a descending branch.