The middle 2/4 of the volar surface of the radius and the adjacent interosseus membrane. (Also occasionally a small origin slightly on the medial epicondyle of the ulna.)


The base of the distal phalanx of the thumb.


The flexor pollicis longus is a flexor of the phalanges of the thumb; when the thumb is fixed, it assists in flexing the wrist.

Nerve Supply

Anterior interosseous nerve (branch of the median nerve) (C8, T1)

Arterial Supply

Anterior interosseus artery

Physical Exam

Enter physical examination maneuvers for muscle

Clinical Importance

Enter clinical importance of muscle

Disease States



The anterior interosseous nerve (a branch of the median nerve) and the anterior interosseous artery and vein pass downward on the front of the interosseous membrane between the flexor pollicis longus and flexor digitorum profundus. Injuries to tendons are particularly difficult to recover from due to the limited blood supply they receive.

Slips may connect with flexor digitorum superficialis, flexor digitorum profundus, or the pronator teres. An additional tendon to the index finger is sometimes found.


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From Wikipedia:
Flexor pollicis longus