Cochlea

Cochlea gebelikten 5 hafta sonra oluşan ve ses dalgalarını algıladıktan sonra bir çeşit sinirsel sinyale dönüştürerek beyne göndermeye yarayan kulağımızın en önemli bölümüdür.

The bony capsule has been dissected out, showing the 2 1/2 coils of the membranous labyrinth (35 mm in length). The oval (o) and round (r) windows are indicated. Bar: 0.5mm



Cross section of the whole cochlea.
This mid-modiolar section shows the coiling of the cochlear duct
(1) containing endolymph and the scala vestibuli
(2) and scala tympani
(3) containing perilymph. The red arrow is from the oval window, the blue arrow points to the round window. Within the modiolus, yellow indicates the spiral ganglion
(4) and auditory nerve fibers
(5). For details, see the single turn cross section below.



The cochlear duct (3) is isolated from the scala vestibuli (1) and scala tympani (2) by the Reissner's (10) and basilar (5) membranes respectively. The organ of Corti is covered by the tectorial membrane (6) floating in the endolymph. The stria vascularis (8) and the fibres (7) going to the spiral ganglion are also indicated.



SEM view of a rat cochlear spiral (the bony capsule, stria and tectorial membrane have been removed)
In rat, the basilar membrane develops a 3 turn spiral of a total length of 22 mm (compare with the coiling in human). Only the extreme base (hook) is not seen.
Yellow boxes link to higher magnification pictures showing the hair cell surfaces and stereocilia at both base and apex.



Distribution of frequencies (passive tonotopy) along the basilar membrane according to G. von Bekesy.
Lines of preferential frequency vibrations (kHz) are indicated in blue on the diagram. Note, from base (20 kHz) to apex (50 Hz), a gradual enlargement of the basilar membrane. See also an uncoiled representation and superimposed traveling waves.


Kaynak
Ses Frekans Tekniği
İ. Eren Başaran