The smaller of two sacs in the vestibule of the inner ear which is part of the mechanism which relates information about the position of the head in space.
The smaller of the two membranous sacs within the vestibule of the ear: it forms part of the membranous labyrinth. It is filled with fluid (endolymph) and contains a macula. This responds to gravity and relays information to the brain about the position of the head.