Extensor pollicis longus muscle

Template:Muscle infobox The Extensor pollicis longus is much larger than the Extensor pollicis brevis muscle, the origin of which it partly covers.

Origin and insertion

It arises from the lateral part of the middle third of the dorsal surface of the body of the ulna below the origin of the Abductor pollicis longus, and from the interosseous membrane.

It ends in a tendon, which passes through a separate compartment in the dorsal carpal ligament, lying in a narrow, oblique groove on the back of the lower end of the radius.

It then crosses obliquely the tendons of the Extensores carpi radialis longus and brevis, and is separated from the Extensor brevis pollicis by a triangular interval, the anatomical snuff box in which the radial artery is found; and is finally inserted into the base of the last phalanx of the thumb.

Relations

The radial artery is crossed by the tendons of the Abductor pollicis longus and of the Extensores pollicis longus and brevis.

Action

The extends the proximal phalanx, and the

Extensor pollicis longus extends the terminal phalanx of the thumb; in combination with the Extensor pollicis brevis, it helps to extend and abduct the wrist.

Additional images

• Anatomical snuff box
  Anatomical snuff box
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  Bones of left forearm. Posterior aspect.
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  Bones of the left hand. Dorsal surface.
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  Tendons of forefinger and vincula tendina.
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  Cross-section through the middle of the forearm.
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  Posterior surface of the forearm. Superficial muscles.
• Posterior surface of the forearm. Deep muscles.
  Posterior surface of the forearm. Deep muscles.
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  Transverse section across the wrist and digits.
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  Arteries of the back of the forearm and hand.

External links

• Template:MuscleLoyola
• Template:GPnotebook
• Template:EMedicineDictionary
• PTCentral