Extensor Pollicis Brevis

General information

Extensor pollicis brevis is a short, slender muscle situated in the forearm’s posterior compartment. The deep forearm extensors consist of the extensor pollicis brevis, supinator, abductor pollicis longus, extensor pollicis longus and extensor indicis muscles.

Literal meaning

The short muscle that straightens the thumb.

Interesting information

As well as belonging to the deep forearm extensors, the extensor pollicis brevis is also a part of the forearm’s deep, posterior fascial compartment.

The muscle also forms part of an anatomical landmark, making up the lateral aspect of the anatomical snuffbox.

Origin

Posterior surface of distal third of radius and interosseus membrane.

Insertion

Posterior aspect of base of proximal phalanx of thumb.

Function 

1st Carpometacarpal and metacarpophalangeal joint: Thumb extension.

Nerve supply

Posterior interosseous nerve (C7, C8).

Blood supply

Posterior interosseous artery, anterior interosseous artery.

Relevant research

Rerouting of the extensor pollicis longus (EPL) is the standard part of tendon transfer surgery for thumb extension. However, extensor pollicis brevis (EPB) produces better thumb abduction and extension when it is rerouted.

Bhardwaj, P., Muddappa, P. P., Bindesh, D., & Sabapathy, S. R. (2019). Evaluation of Extensor Pollicis Brevis as a Recipient of Tendon Transfer for Thumb Extension. Indian journal of plastic surgery: official publication of the Association of Plastic Surgeons of India, 52(2), 171–177.

Extensor pollicis brevis exercises

Strengthening:

Thumb extension - band

Place the resistance band around the top of your thumb and hold the other end of the band. Pull your thumb upwards against the resistance band, relax and repeat.

Stretching:

Thumb extension stretch

Use your two of your fingers to bend your thumb backwards. The stretch will be felt at the bottom of your thumb.