View source for Extensor carpi radialis longus muscle

{{Short description|One of five forearm muscles controlling the wrist}}
{{Infobox muscle
| Name        = Extensor carpi radialis longus
| Latin       = musculus extensor carpi radialis longus
| Image       = Extensor carpi radialis longus.png
| Caption     = Posterior view of the superficial muscles of the left forearm. Extensor carpi radialis longus visible in blue.
| Image2      = Carpal-Tunnel.svg
| Caption2    = Transverse section across the wrist and digits. (Ext. carp. rad. long. labeled at center left.)
| Origin      = [[Lateral supracondylar ridge]]
| Insertion   = [[2nd metacarpal]]
| Blood       = [[Radial artery]]
| Nerve       = [[Radial nerve]]
| Action      = [[Extensor]] at the [[wrist joint]], [[Abduction (kinesiology)|abducts]] the [[hand]] at the [[wrist]]
| Antagonist  = [[Flexor carpi ulnaris muscle]]
}}

The '''extensor carpi radialis longus''' is one of the five main [[muscle]]s that control movements at the [[wrist]].<ref>{{Citation|last=Garten|first=Hans|title=M. extensor carpi radialis (longus and brevis)|date=2013-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780702037399000298|work=The Muscle Test Handbook|pages=58–59|editor-last=Garten|editor-first=Hans|publisher=Churchill Livingstone|language=en|doi=10.1016/b978-0-7020-3739-9.00029-8|isbn=978-0-7020-3739-9|access-date=2020-10-22|url-access=subscription}}</ref> This muscle is quite long, starting on the lateral side of the [[humerus]], and attaching to the base of the [[second metacarpal bone]] (metacarpal of the [[index finger]]).

==Structure==
It originates from the [[lateral supracondylar ridge]] of the [[humerus]], from the [[lateral intermuscular septum of arm|lateral intermuscular septum]], and by a few fibers from the [[lateral epicondyle of the humerus]].<ref name=":0">{{Cite book|title=Color atlas and textbook of human anatomy : in three volumes|publisher=Thieme|last1=Platzer|first1=Werner |last2=Kahle|first2=Werner |others=Frotscher, Michael|year=2003|isbn=978-1-58890-159-0|edition=5th rev. and enlarged [English]|location=Stuttgart|pages=164|oclc=54767617}}</ref>

The fibers end at the upper third of the forearm in a flat tendon, which runs along the lateral border of the [[Radius (bone)|radius]], beneath the [[abductor pollicis longus]] and [[extensor pollicis brevis]]; it then passes beneath the [[dorsal carpal ligament]], where it lies in a groove on the back of the radius common to it and the [[extensor carpi radialis brevis]], immediately behind the [[styloid process (radius)|styloid process]].

One of the three muscles of the [[Mobile wad|radial forearm group]], it initially lies beside the [[Brachioradialis muscle|brachioradialis]], but becomes mostly tendon early on. Passing between the brachioradialis and the [[Extensor carpi radialis brevis muscle|extensor carpi radialis brevis]], this tendon continues into the second tendon compartment together with the latter muscle.<ref name=":0" />

It is inserted into the dorsal surface of the base of the [[second metacarpal bone]], on its radial side.<ref name=":0" />

===Innervation===
The extensor carpi radialis longus is a wrist extensor that is innervated by the [[radial nerve]],<ref name=":0" /><ref>{{Cite journal|last1=Genet|first1=François|last2=Autret|first2=Katell|last3=Schnitzler|first3=Alexis|last4=Lautridou|first4=Christine|last5=Bernuz|first5=Benjamin|last6=Denormandie|first6=Philippe|last7=Allieu|first7=Yves|last8=Parratte|first8=Bernard|date=December 2012|title=Motor Branch of Extensor Carpi Radialis Longus: Anatomic Localization|url=https://doi.org/10.1016/j.apmr.2012.03.015|journal=Archives of Physical Medicine and Rehabilitation|volume=93|issue=12|pages=2309–2312|doi=10.1016/j.apmr.2012.03.015|pmid=22459176|issn=0003-9993|url-access=subscription}}</ref> from [[Spinal nerve|spinal roots]] C6 and C7.<ref>Bradley Bowden, Illustrated Atlas of the Skeletal Muscles, 2005</ref>  All other major extensor muscles in the superficial layer of the posterior compartment (the [[extensor digitorum]], [[extensor carpi radialis brevis]], [[extensor carpi ulnaris]], and [[extensor digiti minimi]]) are innervated by the [[deep branch of radial nerve|posterior interosseous branch]] of the radial nerve.

==Function==
As the name suggests, this muscle is an extensor at the wrist [[joint]] and travels along the radial side of the arm, so it will also abduct (radial abduction) the hand at the wrist.<ref name=":0" />  That is, it manipulates the wrist so as to move the hand towards the [[thumb]] (i.e. [[Abduction (kinesiology)|abduction]]—away from the mid-position of the hand) and away from the palmar side (i.e. [[extension (kinesiology)|extension]]—increased angle between the palm and the front of the forearm).

==Exercises==
The muscle, like all extensors of the forearm, can be [[strength training|strengthened]] by exercise that resist its extension.

===Example exercises===
*[[wrist curl|Reverse wrist curls]] with [[dumbbell]]s can be performed.

==Additional images==
{{gallery|mode=nolines
|Image:Gray417_color.PNG|Cross-section through the middle of the forearm.
|Image:Gray424.png|The mucous sheaths of the tendons on the back of the wrist.
}}

== Notes ==
{{one source|article|date=August 2009}}
{{Reflist}}

== References ==
* {{cite book
| first     = Werner | last = Platzer
| title     = Color Atlas of Human Anatomy, Vol. 1: Locomotor System
| publisher = [[Thieme Medical Publishers|Thieme]] | isbn = 3-13-533305-1<!---US: 1-58890-159-9--->
| year      = 2004 | edition = 5th
}}

{{Muscles of upper limb}}
{{Authority control}}

[[Category:Muscles of the upper limb]]