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{{Short description|Part of SR around T-tubules in muscle}}
{{distinguish|Lumbar cistern{{!}}Terminal cistern at the end of spinal cord}}
{{More citations needed|date=January 2021}}
[[File:Blausen 0801 SkeletalMuscle.png|thumb|300px|[[Skeletal muscle]], with terminal cisterna labeled near bottom.]]
{{wiktionary|terminal cisterna}}
'''Terminal cisternae''' (singular: terminal cisterna) are enlarged areas of the [[sarcoplasmic reticulum]] surrounding the [[transverse tubules]].<ref>{{Citation|last=Kay|first=G. Neal|title=3 - Stimulation and Excitation of Cardiac Tissues|date=2017-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323378048000031|work=Clinical Cardiac Pacing, Defibrillation and Resynchronization Therapy (Fifth Edition)|pages=61–113|editor-last=Ellenbogen|editor-first=Kenneth A.|publisher=Elsevier|language=en|doi=10.1016/b978-0-323-37804-8.00003-1|isbn=978-0-323-37804-8|access-date=2020-11-04|last2=Shepard|first2=Richard B.|editor2-last=Wilkoff|editor2-first=Bruce L.|editor3-last=Kay|editor3-first=G. Neal|editor4-last=Lau|editor4-first=Chu-Pak|url-access=subscription}}</ref>

== Function ==
Terminal cisternae are discrete regions within the muscle cell. They store [[calcium]] (increasing the capacity of the [[sarcoplasmic reticulum]] to release calcium) and release it when an [[action potential]] courses down the transverse tubules, eliciting [[muscle contraction]].<ref name=":0">{{Citation|last=Feher|first=Joseph|title=3.6 - The Neuromuscular Junction and Excitation–Contraction Coupling|date=2017-01-01|url=http://www.sciencedirect.com/science/article/pii/B978012800883600029X|work=Quantitative Human Physiology (Second Edition)|pages=318–333|editor-last=Feher|editor-first=Joseph|place=Boston|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-800883-6.00029-x|isbn=978-0-12-800883-6|access-date=2020-11-04|url-access=subscription}}</ref> Because terminal cisternae ensure rapid calcium delivery, they are well developed in muscles that contract quickly, such as fast twitch [[skeletal muscle]]. Terminal cisternae then go on to release calcium, which binds to [[troponin]]. This releases [[tropomyosin]], exposing active sites of the thin filament, [[actin]].

There are several mechanisms directly linked to the terminal cisternae which facilitate [[Muscle contraction|excitation-contraction coupling]]. When excitation of the membrane arrives at the [[T-tubule]] nearest the [[Myocyte|muscle fiber]], a [[dihydropyridine channel]] ([[DHP channel]]) is activated.<ref name=":0" /> This is similar to a [[voltage-gated calcium channel]], but is not actually an [[Ligand-gated ion channel|ionotropic channel.]] Instead, it serves to activate [[ryanodine]], which will let [[Calcium|calcium ions]] pass into the sarcoplasmic reticulum, and triggers calcium release to the muscle fiber itself.

A T-tubule surrounded by two terminal cisternae is called a [[Triad (anatomy)|triad]]. The terminal cisternae, along with the transverse tubules, are the mechanisms of transduction from a [[Action potential|nervous impulse]] to an actual [[muscle contraction]].

== See also ==
* [[Cistern of lamina terminalis]]
* [[Rexed lamina]]
* [[Preganglionic nerve fiber]]
* [[Postganglionic nerve fiber]]
* [[Splanchnic nerve]]

== References ==
<references />

{{Muscle tissue}}

[[Category:Anatomy articles needing expert attention]]
[[Category:Anatomy]]

{{cell-biology-stub}}

Terminal cisternae - Revision history

imported>OAbot: Open access bot: url-access updated in citation with #oabot.