Deep inside the head is the inner ear, which contains 3 small, fluid-filled structures called the semicircular canals (ducts). Each duct has a swelling at the end called the ampulla. Within the ampulla are tiny "balance" receptors called crista.Update Date: 4/3/2007 Updated by: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Daniel Kantor, M.D., Director of the Comprehensive MS Center, Neuroscience Institute, University of Florida Health Science Center, Jacksonville, FL. Review provided by VeriMed Healthcare Network (5/16/2006).