View source for Extensor retinaculum of the hand

{{Short description|A thickened fascia holding the tendons of the hand extensor muscles in place}}
{{Infobox anatomy
| Name        = Extensor retinaculum of the hand
| Latin       = retinaculum musculorum extensorum manus
| Image       = Gray424.png
| Caption     = The mucous sheaths of the [[tendons]] on the back of the [[wrist]]. (Dorsal carpal ligament labeled at bottom center.)
| Image2      =
| Caption2    =
| System      =
}}
The '''extensor retinaculum''' ('''dorsal carpal ligament''', or '''posterior annular ligament''') is a thickened portion of the [[antebrachial fascia]] that holds the [[tendon]]s of the [[List of extensors of the human body|extensor muscles]] in place.<ref name=":2">{{Cite journal|last1=PALMER|first1=A. K.|last2=SKAHEN|first2=J. R.|last3=WERNER|first3=F. W.|last4=GLISSON|first4=R. R.|date=2016-11-17|title=The Extensor Retinaculum of The Wrist: An Anatomical and Biomechanical Study|url=https://journals.sagepub.com/doi/10.1016/S0266-7681%2885%2980006-1|journal=Journal of Hand Surgery|volume=10|issue=1|pages=11–16|language=en|doi=10.1016/S0266-7681(85)80006-1|pmid=3998587|s2cid=11507945 }}</ref> It is located on the back of the [[forearm]], just [[Proximal#Directions: general usage|proximal]] to the [[hand]].<ref name=":3">{{Cite book|last=Drake, Richard L. (Richard Lee), 1950-|url=https://www.worldcat.org/oclc/55139039|title=Gray's anatomy for students|date=2005|publisher=Elsevier/Churchill Livingstone|others=Vogl, Wayne., Mitchell, Adam W. M., Gray, Henry, 1825-1861.|isbn=0-443-06612-4|location=Philadelphia|oclc=55139039}}</ref> It is continuous with the [[palmar carpal ligament]] (which is located on the anterior side of the forearm).
== Structure ==
The extensor retinaculum is a strong, fibrous band, extending obliquely downward and medialward across the back of the [[wrist]].<ref name=":3" /> It consists of part of the [[deep fascia]] of the back of the [[forearm]], strengthened by the addition of some transverse fibers.{{Citation needed|date=August 2023}}
=== Relations ===
There are six separate synovial sheaths run beneath the extensor retinaculum: (1st) abductor pollicis longus and extensor pollicis brevis tendons, (2nd) extensor carpi radialis longus and brevis tendons, (3rd) extensor pollicis longus tendon, (4th) extensor digitorium communis and extensor indicis proprius tendons, (5th) extensor digiti minimi tendon and (6th) extensor carpi ulnaris tendon.<ref>{{Cite book |url=https://www.worldcat.org/oclc/1132300315 |title=Sobotta anatomy textbook |date=2019 |others=Friedrich Paulsen, Tobias M. Böckers, J. Waschke, Stephan Winkler, Katja Dalkowski, Jörg Mair, Sonja Klebe, Elsevier ClinicalKey |isbn=978-0-7020-6760-0 |location=Munich |oclc=1132300315}}</ref>{{Clarification needed|reason=What is the significance of the numbering? Does it signify a sequence in the mediolateral axis?|date=August 2023}}
On the dorsal side of the hand, the [[palmar carpal ligament]] corresponds in location and structure to the extensor retinaculum, both being formations of the antebrachial fascia and therefore continuous. Consequently, the [[Flexor retinaculum of the hand|flexor retinaculum]] is commonly referred to as the ''transverse carpal ligament'' to avoid confusion.<ref name=":02">{{Cite book |last1=Moore |first1=Keith L. |title=Clinically Oriented Anatomy |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. |publisher=Wolters Kluwer |year=2018 |isbn=978-1-4963-4721-3 |edition=8th |location= |pages=159}}</ref>
=== Histology ===
Structurally, the retinaculum consists of three layers. The deepest layer, the gliding layer, consists of [[hyaluronic acid]]-secreting cells. The thick middle layer consists of  interspersed elastin fibers, collagen bundles, and fibroblasts. The most superficial layer is made up of loose connective tissue which contains vascular channels. Combined these three layers create a smooth gliding surface as well as mechanically strong tissue which prevents tendon bowstringing.<ref name=":0">{{Cite journal |last1=Klein |first1=David M. |last2=Katzman |first2=Barry M. |last3=Mesa |first3=Joseph A. |last4=Lipton |first4=Jeffrey F. |last5=Caligiuri |first5=Daniel A. |date=1999-01-01 |title=Histology of the Extensor Retinaculum of the Wrist and the Ankle |url=http://www.sciencedirect.com/science/article/pii/S0363502399685963 |journal=The Journal of Hand Surgery |language=en |volume=24 |issue=4 |pages=799–802 |doi=10.1053/jhsu.1999.0799 |issn=0363-5023 |pmid=10447172}}</ref> The extensor retinaculum of the foot has similar structure.{{Citation needed|date=August 2023}}
==Clinical significance ==
Studies conducted on the retinaculum have exhibited it to have several possible surgical treatments uses. A graft of the extensor retinaculum was shown to be useful in treating boxer's knuckle when direct repair of the damaged capsule is not possible.<ref name=":1">{{Cite journal|last1=Nagaoka|first1=Masahiro|last2=Satoh|first2=Takako|last3=Nagao|first3=Soya|last4=Matsuzaki|first4=Hiromi|date=2006-07-01|title=Extensor Retinaculum Graft for Chronic Boxer's Knuckle|url=http://www.sciencedirect.com/science/article/pii/S0363502306003820|journal=The Journal of Hand Surgery|language=en|volume=31|issue=6|pages=947–951|doi=10.1016/j.jhsa.2006.02.027|pmid=16843154 |issn=0363-5023}}</ref> Because of their similarities in histological structure, studies also show the extensor retinaculum to be a reasonable biological replacement for reconstruction of a deficient annular pulley.<ref name=":1" />
==Additional images==
<gallery>
File:Gray421.png|Transverse section across distal ends of radius and ulna.
File:Slide2val.JPG|Extensor retinaculum of the hand. Deep dissection.
</gallery>
==References==
<references />
==External links==
* {{KansasHandKinesiology|ligaments/wdsextreti.htm}}
{{Upper limb general}}
{{Authority control}}
[[Category:Human anatomy]]