- A conical cavity in the petrous portion of the temporal bone, forming one of the divisions of the labyrinth or internal ear. It consists of a spiral canal making two and a half turns around a central core of spongy bone, the modiolus; this spiral canal of the c. contains the membranous c., or cochlear duct, in which is the spiral organ (Corti). [L. snail shell]
* * *co·chle·a 'kō-klē-ə, 'käk-lē- n, pl co·chle·as or co·chle·ae 'kō-klē-.ē, 'käk-lē-.ē, -.ī a division of the bony labyrinth of the inner ear coiled into the form of a snail shell and consisting of a spiral canal in the petrous part of the temporal bone in which lies a smaller membranous spiral passage that communicates with the saccule at the base of the spiral, ends blindly near its apex, and contains the organ of Cortico·chle·ar 'kō-klē-ər, 'käk-lē-ər adj
* * *n.the spiral organ of the labyrinth of the ear, which is concerned with the reception and analysis of sound. As vibrations pass from the middle ear through the cochlea, different frequencies cause particular regions of the basilar membrane to vibrate: high notes cause vibration in the region nearest the middle ear; low notes cause vibration in the region nearest the tip of the spiral. The organ of Corti, which lies within a central triangular membrane-bound canal (scala media or cochlear duct), contains sensory hair cells attached to an overlying tectorial membrane. When the basilar membrane vibrates the sensory cells become distorted and send nerve impulses to the brain via the cochlear nerve.• cochlear adj.
* * *coch·lea (kokґle-ə) [L. â€œsnail shellâ€] 1. anything of a spiral form. 2. [TA] a spirally wound tube, resembling a snail shell, which forms part of the internal ear. Its base lies against the lateral end of the internal acoustic meatus and its apex is directed anterolaterally. It consists of the modiolus, a bony canal, and the osseous spiral lamina, which partially divides the cochlea into the essential organs of hearing, the scala vestibuli and scala tympani; the scalae communicate through the helicotrema. cochlear adj
Cochlea and other structures of the bony labyrinth.
Medical dictionary. 2011.