Flexor pollicis longus muscle
|Flexor pollicis longus muscle|
|Front of the left forearm. Deep muscles. (Flexor pollicis longus is shown in blue)|
|Latin||musculus flexor pollicis longus|
|Gray's||subject #125 449|
|Origin:||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.)|
|Insertion:||The base of the distal phalanx of the thumb|
|Artery:||Anterior interosseus artery|
|Nerve:||Anterior interosseous nerve (branch of median nerve) (C8, T1)|
|Action:||Flexion of the thumb.|
|Antagonist:||Extensor pollicis longus muscle, Extensor pollicis brevis muscle|
Origin and insertion
It arises also from the adjacent part of the interosseous membrane of the forearm, and generally by a fleshy slip from the medial border of the coronoid process of the ulna, or from the medial epicondyle of the humerus.
The fibers end in a flattened tendon, which passes beneath the flexor retinaculum of the hand through the carpal tunnel. It is then lodged between the lateral head of the flexor pollicis brevis and the oblique part of the adductor pollicis, and, entering an osseoaponeurotic canal similar to those for the flexor tendons of the fingers, is inserted into the base of the distal phalanx of the thumb.
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.
The flexor pollicis longus is a flexor of the phalanges of the thumb; when the thumb is fixed, it assists in flexing the wrist.
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 As such, some of the information contained herein may be outdated.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.