Vestibular System: Semicircular Canals and Otolith Organs

• The peripheral vestibular system helps stabilize visual images on the fovea of the retina during head movement, and maintains postural stability.
• Each labyrinth contains five neural structures that detect head acceleration: three semicircular canals and two otolith organs.
• The three semicircular canals (SCCs) (horizontal, posterior [inferior], and superior [anterior]) respond to angular acceleration and are orthogonal (at right angles) with respect to one another.
• Alignment of the SCCs in the temporal bone is such that each canal has a contralateral coplanar mate.
• The horizontal canals form a coplanar pair while the posterior and contralateral anterior SCCs form coplanar pairs.
• The anterior aspect of the horizontal SCC is inclined 30° upward from a plane connecting the external auditory canal to the lateral canthus.
• The posterior and anterior SCCs are inclined about 92° and 90°, respectively, from the plane of the horizontal SCC.

The SCCs are tilted by the otolith organs, which are located in the inner ear. These organs respond to changes in head acceleration, and send signals to the SCCs. The SCCs then send signals to the brain, which helps to stabilize visual images on the fovea of the retina.

Test your knowledge about the peripheral vestibular system, including the anatomy and function of the semicircular canals and otolith organs, as well as their role in stabilizing visual images during head movement and maintaining postural stability.