Extensor pollicis longus muscle

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Extensor pollicis longus muscle
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The mucous sheaths of the tendons on the back of the wrist. (Extensor pollicis longus visible at center right.)
Latin musculus extensor pollicis longus
Gray's subject #125 455
Origin: ulna
Insertion: thumb, distal phalanx
Artery:
Nerve: posterior interosseus nerve (branching from the radial nerve)
Action: extension of the thumb (metacarpophalangeal and interphalangeal)
Antagonist: Flexor pollicis longus muscle, Flexor pollicis brevis muscle
Dorlands/Elsevier m_22/12548955

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

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

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