Semicircular canals

Semicircular canals are three tiny, fluid-filled tubes in your inner ear that help you keep your balance. When your head moves, fluid inside the semicircular canals moves. This movement of fluid tells your brain if you're moving in a circle or standing still.

Structure

The semicircular canals are part of the bony labyrinth of the inner ear and are responsible for detecting rotations of the head. They are oriented at right angles to each other and are named according to their orientation: the horizontal semicircular canal, the anterior semicircular canal, and the posterior semicircular canal.

Function

The semicircular canals detect rotational movements. The canals are filled with a fluid called endolymph. When the head rotates, the endolymph in the canals lags behind due to inertia and exerts a force on the cupula. The cupula is a gelatinous structure in the canals, and when it is pushed by the endolymph, it bends the hair cells of the vestibular system. This bending of the hair cells generates a nerve impulse which is sent to the brain to interpret the direction of the head movement.

Clinical significance

Diseases of the semicircular canals can lead to a loss of balance and other symptoms. One such disease is Benign paroxysmal positional vertigo (BPPV), which is a disorder stemming from the inner ear and causes a feeling of spinning.

See also

• Inner ear
• Vestibular system
• Benign paroxysmal positional vertigo

Semicircular_canals

• 
  Vertigo
• 
  Cochlea and vestibular system
• 
  Gray913
• 
  Gray923
• 
  Gray902
• 
  Gray922