Chapter 2 - Overview of anatomy and physiology of the vestibular system

Abstract

This chapter reviews that the vestibular system helps to maintain spatial orientation and stabilize vision for the purpose of maintaining balance, especially during movement. Vestibular end organs sense angular and linear acceleration, and transduce these forces to electrochemical signals that can be used by the central nervous system. It discusses that the central nervous system integrates the information from the vestibular system to stabilize gaze during head motion by means of the vestibulo-ocular reflex (VOR) and to modulate muscle tone by the vestibulocollic and vestibulospinal reflexes. The vestibular system detects angular and linear acceleration through five end organs of the membranous labyrinth on each side: the saccule; the utricle; and the anterior, posterior, and lateral semicircular canals. The saccule and the utricle, the otolith organs, transduce linear accelerations, be they from the pull of gravity or from translation of the head. Each of the semicircular canals has a different spatial orientation; the summation of signals from the semicircular canals allows one to detect rotation of the head in any direction.