Otolith

An otolith (οτο-, oto-, ear + λιθος, lithos, a stone), also called statoconium or otoconium or statolith, is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth of vertebrates. They have been identified in both extinct and extant vertebrates. The saccule and utricle, in turn, together make the otolith organs. They are sensitive to gravity and linear acceleration. Because of their orientation in the head, the utricle is sensitive to a change in horizontal movement, and the saccule gives information about vertical acceleration (such as when in an elevator).

Description

Endolymphatic infillings such as otoliths are structures in the saccule and utricle of the inner ear, specifically in the vestibular labyrinth of all vertebrates (fish, amphibians, reptiles, mammals and birds). In vertebrates, the saccule and utricle together make the otolith organs. Both statoconia and otoliths are used as gravity, balance, movement, and directional indicators in all vertebrates and have a secondary function in sound detection in higher aquatic and terrestrial vertebrates. They are sensitive to gravity and linear acceleration. Because of their orientation in the head, the utricle is sensitive to a change in horizontal movement, and the saccule gives information about vertical acceleration (such as when in an elevator).