The function of extensor pollicis longus tendon is to stretch the thumb, and the function of extensor pollicis brevis tendon is to stretch the thumb. Abductor pollicis longus originates from the tendon and forearm interosseous membrane on the dorsal side of radius and ulna, and runs in the deep surface of extensor carpi radialis, extensor digitorum and above extensor pollicis brevis, as well as in the deep layer of extensor retinaculum. The abductor pollicis longus tendon and extensor pollicis brevis tendon run in the same fiber sheath, and then the abductor pollicis longus tendon stops at the base of the first metacarpal bone.

1. The starting and ending points are different: the extensor pollicis longus tendon is innervated by the radial nerve, starting from the dorsal side of the ulna and radius and the interosseous membrane, and ending at the base of the phalanx of the thumb. The extensor pollicis brevis tendon is innervated by the radial nerve, starting from the dorsal side of the ulna and radius and the interosseous membrane, and ending at the phalangeal base of the thumb 1. Abductor pollicis longus starts from the back of radius and ulna and the interosseous membrane of forearm, and ends at the base of the first metacarpal bone.

2. Their positions are different: extensor pollicis brevis tendon is located on the ulnar side of abductor pollicis longus tendon. Abductor pollicis longus tendon is located on the radial side of extensor pollicis brevis tendon, abductor pollicis longus tendon and extensor pollicis brevis tendon are located in the superficial layer of extensor carpi radialis tendon, and extensor pollicis longus tendon is located in the deep layer of forearm.

Extended data:

The rupture of extensor pollicis longus tendon mostly occurs in male gymnasts, especially in the groove of extensor pollicis longus tendon in radius. This kind of tendon is prone to chronic inflammation or degeneration after wear and tear, and it is easy to break. After fracture, the distal thumb can't extend backward actively, but the function of thumb abduction and proximal phalanx extension is normal. The problem of extensor pollicis brevis tendon may lead to mild hallux valgus. When the extensor pollicis brevis tendon contracts, it can not only make the thumb extend backward, but also make the thumb abduct.

Anatomically, snuff fossa refers to a triangular fossa on the back of wrist, whose inner edge is extensor pollicis longus tendon, which passes through the fibrous sheath of bone and ends at the root of distal thumb. The lateral margin is abductor pollicis longus tendon and extensor pollicis brevis tendon.

References:

Baidu encyclopedia-extensor pollicis longus

Baidu encyclopedia-extensor pollicis brevis

Baidu Encyclopedia-Kidnappers have long thumbs.