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The lateral semicircular canal (also known as horizontal or external semicircular canal) is the shortest of the three canals.Movement of fluid within its duct corresponds to rotation of the head around a vertical axis (i.e. the neck), or in other words, rotation in the transverse plane.
Running parallel with the perilymphatic duct is a separate blind-ending duct, the lagena, filled with endolymph. The lagena is separated from the perilymphatic duct by a basilar membrane, and contains the sensory hair cells that finally translate the vibrations in the fluid into nerve signals. It is attached at one end to the saccule.
Movement of fluid within the horizontal semicircular canal corresponds to rotation of the head around a vertical axis (i.e. the neck), as when doing a pirouette. The anterior and posterior semicircular canals detect rotations of the head in the sagittal plane (as when nodding), and in the frontal plane, as when cartwheeling. Both anterior and ...
The receptor cells located in the semicircular ducts are innervated by the eighth cranial nerve, the vestibulocochlear nerve (specifically the vestibular portion). The crista ampullaris itself is a cone-shaped structure, covered in receptor cells called "hair cells".
Within the gelatinous layer lie otoliths, tiny formations of calcium carbonate. When a person moves, these otoliths shift position. This shift alters the positions of the filaments, which opens ion channels within the cell membranes, creating depolarisation and an action potential that is transmitted to the brain along the vestibulocochlear nerve.
Information from the semicircular canals reflects rotational movement of the head. Both are necessary for the sensation of body position and gaze stability in relation to a moving environment. Axons of the vestibular nerve synapse in the vestibular nucleus are found on the lateral floor and wall of the fourth ventricle in the pons and medulla.
The vestibule is the central part of the bony labyrinth in the inner ear, and is situated medial to the eardrum, behind the cochlea, and in front of the three semicircular canals. [ 1 ] The name comes from the Latin vestibulum , literally an entrance hall.
The bony labyrinth (also osseous labyrinth or otic capsule) is the rigid, bony outer wall of the inner ear in the temporal bone.It consists of three parts: the vestibule, semicircular canals, and cochlea.