Anatomy of Abductor #Pollicis Longus

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

ABDUCTOR POLLICIS LONGUS

• The Abductor Pollicis Longus is an important muscle .
• It is one of the extrinsic muscles of the hand.

ORIGIN: It arises from the posterior surface of the ulna, radius and the interosseous membrane.

INSERTION: The APL is inserted into the base of the first metacarpal bone.

FUNCTION: It abducts and extends the thumb of the carpometacarpal joint.

INNERVATION: APL is innervated by the posterior interosseous nerve.

DE QUERVAIN’S SYNDROME: Both Abductor Pollicis Longus and Extensor Pollicis Brevis are involved in this syndrome.

De Quervain’s syndrome mainly occurs in:
o Women
o Golfers
o Racquets sports
o May occur due to overuse
o May occur post partum
o It may occur without any specific cause

FINKELSTEIN’S TEST is used to diagnose De Quervain’s tenosynovitis in patients who have wrist pain.

• It is conducted by making a fist with the fingers closed over the thumb and the wrist is bent towards the little finger.
• The wrist is then pulled so that the tendons of the first dorsal compartment are stretched distally causing sharp local pain, if tendon inflammation is present.
• If the tenderness is located about 5 cm proximal to the wrist joint, it may be INTERSECTION SYNDROME.
• De Quervain’s syndrome is a stenosing inflammatory condition involving the first dorsal compartment of the wrist.
• Recurrence of symptoms may be due to failure of decompression of the tendons due to unusual anatomy.

 

• The APL is also associated with BENNETT FRACTURES – The volar ulnar beak fracture fragment attached to the palmar oblique ligament.
• The distal part of the first metacarpal is adducted by the adductor pollicis muscle.
• The metacarpal shaft is displaced proximally by the abductor pollicis longus muscle.