Abductor pollicis brevis muscle

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Abductor pollicis brevis muscle
Abductor pollicis brevis visible at center right.
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The mucous sheaths of the tendons on the back of the wrist. (Abductor pollicis longus and brevis visible at center right, going into thumb.)
Latin musculus abductor pollicis brevis
Gray's subject #126 461
Origin: Transverse carpal ligament, the scaphoid and trapezium [1]
Insertion: Radial base of proximal phalanx of thumb and the thumb extensors [1]
Artery:
Nerve: Median nerve
Action:
Antagonist: Adductor pollicis muscle
Dorlands/Elsevier m_22/12548307

The abductor pollicis brevis is a muscle in the hand that functions as an abductor of the thumb.

Structure

The abductor pollicis brevis is a flat, thin muscle located just under the skin. It is a thenar muscle, and therefore contributes to the bulk of the palm's thenar eminence.

It originates from the flexor retinaculum of the hand, the tubercle of the scaphoid bone, and additionally sometimes from the tubercle of the trapezium.

Running lateralward and downward, it is inserted by a thin, flat tendon into the lateral side of the base of the first phalanx of the thumb and the capsule of the metacarpophalangeal joint.

Innervation

The abductor pollicis brevis is usually innervated by the recurrent branch of the median nerve, but is occasionally innervated (in whole or in part) by the deep branch of the ulnar nerve.

Actions

Abduction of the thumb is defined as the movement of the thumb anteriorly, a direction perpendicular to the palm. The abductor pollicis brevis does this by acting across both the carpometacarpal joint and the metacarpophalangeal joint.

It also assists in opposition and extension of the thumb.

Additional images

References

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 As such, some of the information contained herein may be outdated.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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