cochlear duct
{{Short description|Cavity in the cochlea of the inner ear}}
{{More citations needed|date=January 2009}}
{{Infobox anatomy
| Name = Cochlear duct
| Latin = ductus cochlearis
| Greek =
| Image = Blausen 0329 EarAnatomy InternalEar.png
| Caption = Inner ear, with cochlear duct labeled near bottom.
| Width = 400px
| Image2 = Gray928.png
| Caption2 = Diagrammatic longitudinal section of the cochlea. (visible at far right under latin name ductus cochlearis)
| Precursor =
| System =Ear
| Artery =
| Vein =
| Nerve =
| Lymph =
}}
The cochlear duct (a.k.a. the scala media) is an endolymph filled cavity inside the cochlea, located between the tympanic duct and the vestibular duct, separated by the basilar membrane and the vestibular membrane (Reissner's membrane) respectively. The cochlear duct houses the organ of Corti.{{Cite book|last1=Hayes|first1=Sarah H.|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780702053108000016|title=Handbook of Clinical Neurophysiology|last2=Ding|first2=Dalian|last3=Salvi|first3=Richard J.|last4=Allman|first4=Brian L.|publisher=Elsevier|year=2013|isbn=978-0-7020-5310-8|volume=10|pages=3–23|language=en|chapter=1 – Anatomy and physiology of the external, middle and inner ear|doi=10.1016/B978-0-7020-5310-8.00001-6|issn=1567-4231}}
Structure
The cochlear duct is part of the cochlea. It is separated from the tympanic duct (scala tympani) by the basilar membrane.{{Cite book|last=Feher|first=Joseph|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780128008836000409|title=Quantitative Human Physiology – An Introduction|publisher=Academic Press|year=2012|isbn=978-0-12-800883-6|edition=2nd|pages=440–455|language=en|chapter=4.7 – Hearing|doi=10.1016/B978-0-12-800883-6.00040-9}} It is separated from the vestibular duct (scala vestibuli) by the vestibular membrane (Reissner's membrane). The stria vascularis is located in the wall of the cochlear duct.
= Development =
The cochlear duct develops from the ventral otic vesicle (otocyst).{{Cite book|last=Fekete|first=D. M.|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780080450469002527|title=Encyclopedia of Neuroscience|publisher=Academic Press|year=2009|isbn=978-0-08-045046-9|pages=1031–1040|language=en|chapter=Cochlear Development|doi=10.1016/B978-008045046-9.00252-7}} It grows slightly flattened between the middle and outside of the body. This development may be regulated by the genes EYA1, SIX1, GATA3, and TBX1. The organ of Corti develops inside the cochlear duct.{{Cite book|last1=Goodyear|first1=Richard J.|chapter-url=https://www.sciencedirect.com/science/article/pii/S0070215318300383|title=Current Topics in Developmental Biology|last2=Richardson|first2=Guy P.|publisher=Elsevier|year=2018|isbn=978-0-12-809802-8|volume=130|pages=217–244|language=en|chapter=6 – Structure, Function, and Development of the Tectorial Membrane: An Extracellular Matrix Essential for Hearing|doi=10.1016/bs.ctdb.2018.02.006|pmid=29853178 |issn=0070-2153}}
Function
The cochlear duct contains the organ of Corti.{{Cite book|last=Spelman|first=Francis A.|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780080877808000838|title=Biomaterials Science – An Introduction to Materials in Medicine|publisher=Academic Press|year=2013|isbn=978-0-12-374626-9|edition=3rd|pages=967–980|language=en|chapter=2.5.11 – Cochlear Prostheses|doi=10.1016/B978-0-08-087780-8.00083-8}} This is attached to the basilar membrane. It also contains endolymph, which contains high concentrations of K+ for the function of inner hair cells and outer hair cells in the organ of Corti.
Clinical significance
Drugs delivered directly to the tympanic duct will spread to all of the cochlea except for the cochlear duct.{{Cite book|last1=Shepherd|first1=R. K.|chapter-url=https://www.sciencedirect.com/science/article/pii/B9781782421016000057|title=Implantable Neuroprostheses for Restoring Function|last2=Seligman|first2=P. M.|last3=Fallon|first3=J. B.|publisher=Woodhead Publishing|year=2015|isbn=978-1-78242-101-6|pages=97–125|language=en|chapter=5 – Neuroprostheses for restoring hearing loss|doi=10.1016/B978-1-78242-101-6.00005-7}} Rarely, the cochlear duct may develop to have the wrong shape.
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
{{Reflist}}
External links
- [http://www.avatar.com.au/courses/PPofM/hearing/hearing3.html Cross section] at avatar.com.au
{{Auditory and vestibular anatomy}}
{{Authority control}}