NEUROSCIENCE: VESTIBULAR SYSTEM -- Introduction

INTRODUCTION to the Vestibular System

A. Located in the inner ear (labyrinth)

1. bony labyrinth: cavity within temporal bone

2. membranous labyrinth: two concentric tubes

a. space between outer and inner filled with perilymph (similar to CSF)
b. inner filled with endolymph (high in K⁺) (due to K⁺ secretion)

B. Sensory organs of inner ear

1. Cochlea (hearing); cochlear branch of VIIIth nerve

2. Vestibular (orientation and equilibrium); vestibular branch of VIIIth nerve

a. Utricle and saccule (2 organs) -- linear movement & gravity

b. Semicircular canals (3 canals oriented in mutually perpendicular planes) -- rotational (angular) movement