perilymph: Definition from Answers.com

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Cross-section of cochlea. Perilymph is located in the scala tympani and scala vestibuli - the aqua regions at the top and bottom of the diagram.

Perilymph is an extracellular fluid located within the cochlea (part of the ear) in 2 of its 3 compartments; the scala tympani and scala vestibuli. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major cation of perilymph is sodium.

1 Perilymph vs. endolymph
2 Clinical significance
3 References
4 External links

Perilymph vs. endolymph

The third compartment of the ear, the cochlear duct (or scala media) contains endolymph. Perilymph and endolymph have unique ionic compositions suited to their functions in regulating electrochemical impulses of hair cells. The electric potential of endolymph is ~80-90 mV more positive than perilymph due to a higher concentration of K compared to Na.^[1]

Clinical significance

It has also been suggested that perilymph and endolymph participate in a unidirectional flow that is interrupted in Meniere's disease.

References

^ Konishi T, Hamrick PE, Walsh PJ (1978). "Ion transport in guinea pig cochlea. I. Potassium and sodium transport". Acta Otolaryngol. 86 (1-2): 22–34. doi:10.3109/00016487809124717. PMID 696294.

External links

http://oto.wustl.edu/cochlea/intro3.htm

Sensory system: Auditory and Vestibular systems (TA A15.3, GA 10.1029)

Auditory

Outer ear	Pinna (Helix, Antihelix, Tragus, Antitragus, Earlobe) • Ear canal

Middle ear	Eardrum (Umbo) • Ossicles (Malleus, Incus & Stapes) • muscles (Stapedius, Tensor tympani) • Eustachian tube (Torus tubarius)

Inner ear/Labyrinth	Vestibule • Membranous labyrinth Oval window → Scala vestibuli / Reissner's/vestibular membrane, Helicotrema and Scala tympani / Basilar membrane (Perilymph) → Round window Cochlea: Modiolus • Cochlear duct / scala media (Endolymph, Stria vascularis, Spiral ligament), Olivocochlear system Organ of Corti: Stereocilia • Tectorial membrane • Sulcus spiralis (externus, internus) • Limbus spiralis

To brain	Hair cells → Spiral ganglion → Cochlear nerve ^VIII → Cochlear nuclei → Trapezoid body → Superior olivary nuclei → Lateral lemniscus → Inferior colliculi → Medial geniculate nuclei → Acoustic radiation → Primary auditory cortex

Vestibular

Inner ear/Labyrinth	Static/translations: Utricle (Macula) · Saccule (Macula, Endolymphatic sac, Endolymphatic duct) · Kinocilium · Otolith Kinetic/rotations: Semicircular canals (Superior, Posterior, Horizontal) • Cupula • Ampullae (Crista ampullaris)

To brain	Vestibular nerve ^VIII → Vestibular nuclei, Flocculonodular lobe Vestibular nuclei → Vestibulospinal tract, Ventral posterolateral nucleus → Vestibular cortex

ear navs: anat/physio/dev, noncongen/congen, eponymous signs, proc

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perilymph

Contents

Perilymph vs. endolymph

Clinical significance

References

External links