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A partition between the scalae of the cochlea. The largest part of this, next the modiolus, is formed of bone. The remainder, or that part nest the opposite side of the scalae, is composed of a cartilaginous membrane, called, by Valsalva, Zona seu Zonula Cochleae. By some anatomists, the lamina is divided into a Zona ossea and Z. mollis. By others, it is considered to consist of four laminae, when examined with a strong glass: a Zona ossea, next to the modiolus- a Zona coriacea, on the outer side of this: a Zona vesicularis- and a Zona membranacea, which is, perhaps, the lining membrane of the cochlea. At the apex of the cochlea, the lamina spiralis terminates by a pointed hook-shaped process, hamulus laminae spirallis.

partition which divides the cochlea into the two scalae.

Syn.: crista spiralis. A l. which divides the interior of the spiral canal of the cochlea into two scalae. It is divided into the l. spiralis ossea and the l. spiralis membranacea, or membrana.