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#REDIRECT [[Anatomical terms of motion#Flexion and extension]]
[[Image:BodyPlanes.jpg|thumb|right|300px|Anatomical planes in a human. Extension usually occurs in the coronal plane when the body is in the [[anatomical position]]]]
[[Image:LegExtensionMachineExercise.JPG|thumb|300px|The ''leg extension'' is an isolation exercise.]]
'''Extension''' is a movement of a joint. For example, extension is produced by extending the flexed elbow. The arm is now straight; it has been extended. If the head is tilted all the way back, it is said to be extended.
The movement in the opposite directions is called [[flexion]]. Flexion decreases the angle between the bones of the limb at a joint, while extension increases it.
With the [[foot]], extension (elevation) is usually called [[Dorsiflexion]].
If a part of the body is overstretched, then one speaks of a [[Hyperextension]] (as with the [[knee]]).
In some anatomical muscle names, particularly with muscles of the [[forearm]] and the [[Cnemis]], the term occurs explicitly as the second word in the Latin spelling of the name (for example, [[Musculus extensor carpi ulnaris]]).
==Muscles of extension==
===Upper limb===
* of [[forearm]] at [[elbow]]<ref>http://www.exrx.net/Articulations/Elbow.html#anchor764495</ref>
** [[Posterior compartment of the arm]]
*** [[Triceps]]
*** [[Anconeus]]
* of [[hand]] at [[wrist]]<ref>http://www.exrx.net/Articulations/Wrist.html#anchor261877</ref>
** [[Posterior compartment of the forearm]]
*** [[Extensor carpi radialis longus]]
*** [[Extensor carpi radialis brevis]]
*** [[Extensor digitorum]]
* of [[phalanges]], at all joints
** [[Posterior compartment of the forearm]]
*** [[Extensor digitorum]]
*** [[Extensor carpi ulnaris]]
*** [[Extensor digiti minimi]] (little finger only)
*** [[Extensor indicis]] (little finger only)
* of [[phalanges]], at [[interphalangeal joints]]<ref>http://www.exrx.net/Articulations/Fingers.html#anchor783765</ref>
** [[Lumbricals of the hand]]
** [[Dorsal interossei of the hand]]
** [[Palmar interossei]]
* of [[thumb]]<ref>http://www.exrx.net/Articulations/Thumb.html#anchor206622</ref><ref>http://www.exrx.net/Articulations/Thumb.html#anchor210115</ref>
** [[Extensor pollicis brevis]] (proximal phalange)
** [[Extensor pollicis longus]] (distal phalange)
===Lower limb===
* of [[thigh]]/[[femur]] at [[hip]]<ref>http://www.exrx.net/Articulations/Hip.html#anchor845621</ref>
** [[Gluteus maximus muscle|Gluteus maximus]]
** [[Posterior compartment of thigh]]
*** [[Biceps femoris muscle|Biceps femoris]]
*** [[Semitendinosus muscle|Semitendinosus]]
*** [[Semimembranosus muscle|Semimembranosus]]
* of [[leg]] at [[knee]] (L3-L4)<ref>http://www.exrx.net/Articulations/Knee.html#anchor22459</ref>
** [[Quadriceps muscle|Quadriceps]]
*** [[Rectus femoris muscle]]
*** [[Vastus medialis]]
*** [[Vastus lateralis]]
*** [[Vastus intermedius]]
* of [[toes]]<ref>http://www.exrx.net/Articulations/Toes.html#anchor231444</ref><ref>http://www.exrx.net/Articulations/Toes.html#anchor235208</ref>
** [[Extensor hallucis longus]]
** [[Extensor digitorum longus]]
** [[Extensor digitorum brevis]]
** [[Extensor hallucis brevis]]
==References==
<references/>
==External links==
* {{eMedicineDictionary|Extension}}
{{anatomy-stub}}
{{Joints}}
[[de:Extension (Medizin)]]
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