utricle is the larger inner ear otolithic organ that helps sense the position of the head in space.
utricle is the larger inner ear otolithic organ that helps sense the position of the head in space.
which larger inner ear otolithic organ helps sense the position of the head in space?
utricle
the otolithic membrane is part of the otolith organs in the vestibular system. the otolith organs include the utricle and the saccule. the otolith organs are beds of sensory cells in the inner ear, specifically small patches of hair cells. overlying the hair cells and their hair bundles is a gelatinous layer and above that layer is the otolithic membrane. the utricle serves to measure horizontal accelerations and the saccule responds to vertical accelerations. the reason for this difference is the orientation of the macula in the two organs. the utricular macula lie horizontal in the utricle, while the saccular macula lies vertical in the saccule. every hair cell in these sensory beds consist of 40-70 stereocilia and a kinocilium. the sterocilia and kinocilium are embedded in the otolithic membrane and are essential in the function of the otolith organs. the hair cells are deflected by structures called otoconia.
otolithic membrane
within the macula are hair cells, each having a hair bundle on the apical aspect. the hair bundle is composed of a single kinocilium and many (at least 70) stereocilia. stereocilia are connected to mechanically gated ion channels in the hair cell plasma membrane via tip links. supporting cells interdigitate between hair cells and secrete the otolithic membrane, a thick, gelatinous layer of glycoprotein. covering the surface of the otolithic membrane are otoliths, which are crystals of calcium carbonate. for this reason, the saccule is sometimes called an "otolithic organ."
saccule