Abductor pollicis muscle

Abductor Pollicis Longus Muscle

Abductor pollicis longus muscle (shown in red). Image via Gray's Anatomy.

The Abductor Pollicis Longus (APL) is one of the extrinsic muscles of the hand. Its major function is to abduct the thumb at the wrist. Its tendon forms the lateral border of the anatomical snuffbox.

Origin and Insertion

The APL originates from the posterior surfaces of the ulna and radius, and the interosseous membrane. It inserts into the base of the first metacarpal bone and the trapezium.

Innervation

The APL is innervated by the Posterior interosseous nerve, a branch of the Radial nerve.

Function

The primary function of the APL is to control thumb movement. It abducts and extends the thumb at the carpometacarpal and metacarpophalangeal joints.

Clinical Significance

Injury to the APL can result in loss of thumb abduction, which can significantly impact hand function.

See Also

• Anatomical snuffbox
• Extrinsic muscles of the hand
• Radial nerve
• Posterior interosseous nerve