The cochlear duct (bounded by the scala media) is an

endolymph Endolymph is the fluid contained in the membranous labyrinth of the inner ear. The major cation in endolymph is potassium, with the values of sodium and potassium concentration in the endolymph being 0.91 mM and 154 mM, respectively. I ...

filled cavity inside the

cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the Organ of Corti, the sensory org ...

, located between the

tympanic duct The tympanic duct or scala tympani is one of the perilymph-filled cavities in the inner ear of humans. It is separated from the cochlear duct by the basilar membrane, and it extends from the round window to the helicotrema, where it continues as ...

and the

vestibular duct The vestibular duct or scala vestibuli is a perilymph-filled cavity inside the cochlea of the inner ear that conducts sound vibrations to the cochlear duct. It is separated from the cochlear duct by Reissner's membrane and extends from the vesti ...

, separated by the

basilar membrane The basilar membrane is a stiff structural element within the cochlea of the inner ear which separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani. The basilar membrane moves up and down ...

and the vestibular membrane (Reissner's membrane) respectively. The cochlear duct houses the

organ of Corti The organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea. This highly varied strip of epithelial cells allows for transduction of auditory signals into nerve impulses' action potential. Transd ...

Structure

The cochlear duct is part of the

. It is separated from the

(scala tympani) by the

. It is separated from the

(scala vestibuli) by the vestibular membrane (Reissner's membrane). The

stria vascularis The stria vascularis of the cochlear duct is a capillary loop in the upper portion of the spiral ligament (the outer wall of the cochlear duct). It produces endolymph for the scala media in the cochlea. Structure The stria vascularis is part o ...

is located in the wall of the cochlear duct.

Development

The cochlear duct develops from the ventral

otic vesicle Otic vesicle, or auditory vesicle, consists of either of the two sac-like invaginations formed and subsequently closed off during embryonic development. It is part of the neural ectoderm, which will develop into the membranous labyrinth of the in ...

(otocyst). It grows slightly flattened between the middle and outside of the body. This development may be regulated by the genes EYA1,

SIX1 Homeobox protein SIX1 (Sine oculis homeobox homolog 1) is a protein that in humans is encoded by the ''SIX1'' gene. Function The vertebrate SIX genes are homologs of the Drosophila 'sine oculis' (so) gene, which is expressed primarily in the ...

GATA3 GATA3 is a transcription factor that in humans is encoded by the ''GATA3'' gene. Studies in animal models and humans indicate that it controls the expression of a wide range of biologically and clinically important genes. The GATA3 transcription ...

, and

TBX1 T-box transcription factor TBX1 also known as T-box protein 1 and testis-specific T-box protein is a protein that in humans is encoded by the TBX1 gene. Genes in the T-box family are transcription factors that play important roles in the formation ...

. The organ of Corti develops inside the cochlear duct.

Function

The cochlear duct contains the

. This is attached to the basilar membrane. It also contains

, which contains high concentrations of K⁺ for the function of

inner hair cells Hair cells are the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates, and in the lateral line organ of fishes. Through mechanotransduction, hair cells detect movement in their environment. ...

and

outer hair cells Hair cells are the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates, and in the lateral line organ of fishes. Through mechanotransduction, hair cells detect movement in their environment. ...

in the organ of Corti.

Clinical significance

Drugs delivered directly to the

will spread to all of the

except for the cochlear duct. Rarely, the cochlear duct may develop to have the wrong shape.

History

The cochlear duct is the space bounded by the scala media.

Additional images

File:Gray903.png, Transverse section of the cochlear duct of a fetal cat. File:Gray924.png, The membranous labyrinth. File:Gray929.png, Floor of ductus cochlearis. File:Cochlea-crosssection.svg, Cross section of the cochlea.

References

External links

Cross section
at avatar.com.au {{Authority control Ear Auditory system