The investigations showed an accessory extensor pollicis longus muscle which was also found in a third extensor compartment.
Variation of extensor pollicis longus muscle is a rare anatomical anomaly (Wang & Weiss, 2013) but knowledge of it, is immense significant because it plays an important role especially during radiological diagnosis and surgical procedures such as reconstructive surgery.
(2012) used the radial half of the ECRL muscle tendon to reconstruct the tendon of the extensor pollicis longus muscle
, since a graft from the inserted tendon was not possible given the absence of the PL muscle, and they obtained excellent results, comparable to those obtained using the fascia lata.
1), is laterally limited by the tendons of abductor pollicis longus and extensor pollicis brevis muscles, and medially limited by the tendon of extensor pollicis longus muscle (Latarjet & Ruiz-Liard).
1= tendon of extensor pollicis longus muscle; 2= tendon of extensor pollicis brevis muscle; 3= head of the first metacarpal bone; 4= anatomical snuffbox.
1= tendon of abductor pollicis longus muscle; 2= tendon of extensor pollicis brevis muscle; 3= tendon of extensor pollicis longus muscle; 4= cephalic vein; 5= terminal branches of the superficial branch of radial nerve; 6= radial artery; 7= superficial branch of radial nerve; 8= retinaculum of extensor muscles; 9= tendon of extensor carpi radialis longus muscle; 10= tendon of extensor carpi radialis brevis muscle.
Specifically, the authors (5) required the subjects to perform simultaneous isometric muscle actions of the flexor pollicis longus and extensor pollicis longus muscles
for the purpose of stiffening the interphalangeal joint of the thumb and producing zero net force.