ear, nose, and throat disorders
Overview of the Inner Ear
Vestibular system
The vestibular system consists of two fluid-filled sacs called the saccule and the utricle and three fluid-filled tubes called the semicircular canals. These sacs and tubes gather information about the position and movement of the head. The brain uses this information to help maintain balance. Thesacculeandutricleare located in the vestibule and contain cells that sense movement of the head from side to side (horizontally), sensing acceleration, or up and down (vertically), sensing gravity. Thesemicircular canalsare three fluid-filled tubes at right angles to one another that sense rotation of the head. Rotation of the head causes the fluid in the canals to move. Depending on the direction the head moves, the fluid movement is greater in one of the canals than in the others. The canals contain hair cells that respond to this movement of fluid. The hair cells initiate nerve impulses that tell the brain which way the head is moving so that appropriate action can be taken to maintain balance. If the semicircular canals malfunction, which can occur in an upper respiratory infection or other temporary or permanent disorders, the person's sense of balance may be lost or a false sensation of moving or spinning ( Dizziness and Vertigo ) may develop. 