Cochlea

One of the three divisions of the internal ear, similar in shape to an ordinary snail shell, and consisting of two coils and a half about an axis or "modiolus." The outer wall is of bone, and the whole is imbedded in the petrous portion of the temporal bone of the skull. Within it is a hollow pa age winding spirally to the summit and divided by a plate of bone and two membranes into three canals; the scala tym pan i, facing the base of the cochlea, the scala vestibuli, facing the apex, and the canal is cochlear is, between the other two. The lower of the two dividing membranes supports the ORGAN OF CORTI (q.v.).