Abductor pollicis brevis muscle

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

Abductor pollicis brevis muscle
Superficial muscles of the left hand, palmar view
Details
OriginTransverse carpal ligament, the scaphoid and trapezium[1]
InsertionRadial base of proximal phalanx of thumb and the thumb extensors[1]
ArterySuperficial palmar arch
NerveRecurrent branch of the median nerve
ActionsAbduction of the thumb by acting across the carpometacarpal joint and the metacarpophalangeal joint. It also assists in opposition and extension of the thumb.
AntagonistAdductor pollicis muscle
Identifiers
Latinmusculus abductor pollicis brevis
TA98A04.6.02.054
TA22521
FMA37373
Anatomical terms of muscle

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.

Nerve supply

The abductor pollicis brevis is supplied by the recurrent branch of the median nerve (Roots C5- C7 and C8-T1 in the brachial plexus lateral and medial cords respectively).[2][3]

Function

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
  • Cadaver dissection

References

This article incorporates text in the public domain from page 461 of the 20th edition of Gray's Anatomy (1918)

  1. Eatonhand - Abductor Pollicis Brevis
  2. Preston, David C.; Shapiro, Barbara E. (2013-01-01), Preston, David C.; Shapiro, Barbara E. (eds.), "6 - Repetitive Nerve Stimulation", Electromyography and Neuromuscular Disorders (Third Edition), London: W.B. Saunders, pp. 52–61, doi:10.1016/b978-1-4557-2672-1.00006-4, ISBN 978-1-4557-2672-1, retrieved 2020-10-24
  3. Visser, Gerhard H.; Blok, Joleen H. (2009-01-01), Bromberg, M. B. (ed.), "Chapter 6 - The CMAP scan", Supplements to Clinical Neurophysiology, Motor Unit Number Estimation (MUNE) and Quantitative EMG, Elsevier, 60, pp. 65–77, doi:10.1016/s1567-424x(08)00006-8, retrieved 2020-10-24
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