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The lateral semicircular duct is about a 30-degree angle from the horizontal plane. The orientations of the ducts cause a different duct to be stimulated by movement of the head in different planes, and more than one duct is stimulated at once if the movement is off those planes. The lateral semicircular duct detects angular acceleration of the ...
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".
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 .
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 ampullary cupula, or cupula, is a structure in the vestibular system, providing the sense of spatial orientation. The cupula is located within the ampullae of each of the three semicircular canals. Part of the crista ampullaris, the cupula has embedded within it hair cells that have several stereocilia associated with each kinocilium. The ...
The semicircular canals and sacs in all vertebrates are attached to endolymphatic ducts, which in some groups (such as sharks) end in small openings, called endolymphatic pores, on the dorsal surface of the head. [1] Extrinsic grains may enter through these openings, typically less than a millimeter in diameter.
The vestibular system is important for balance, or equilibrium. It includes the saccule, utricle, and the three semicircular canals. The vestibule is the name of the fluid-filled, membranous duct that contains these organs of balance and is in turn encased in the temporal bone of the skull as a part of the inner ear.
From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch (endolymphatic sac) on the posterior surface of the petrous portion of the temporal bone, where it is in contact with the dura mater.