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The extensor pollicis brevis arises from the ulna distal to the abductor pollicis longus, from the interosseous membrane, and from the dorsal surface of the radius. [1]Its direction is similar to that of the abductor pollicis longus, its tendon passing the same groove on the lateral side of the lower end of the radius, to be inserted into the base of the first phalanx of the thumb.
Structure. The abductor pollicis brevis is a flat, thin muscle located just under the skin. It is a thenar muscle, and therefore contributes to the bulk of the palm's thenar eminence. It originates from the flexor retinaculum of the hand, the tubercle of the scaphoid bone, and additionally sometimes from the tubercle of the trapezium.
An accessory abductor pollicis longus (AAPL) tendon is present in more than 80% of people, and a separate muscle belly is present in 20% of people. In one study, the accessory tendon was inserted into the trapezium (41%); proximally on the abductor pollicis brevis (22%) and opponens pollicis brevis (5%); had a double insertion on the trapezium and thenar muscles (15%); or the base of the first ...
The extensor pollicis brevis originates on the ulna distal to the abductor pollicis longus, from the interosseus membrane, and from the dorsal side of the radius. Passing through the first tendon compartment together with the abductor pollicis longus, it is attached to the base of the proximal phalanx of the thumb.
Moving distally, there are the abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis (EI). The APL originates from the lateral part of the dorsal surface of the body of the ulna below the insertion of the anconeus and from the middle third of the dorsal surface of the body of the ...
Extensor pollicis longus extends the terminal phalanx of the thumb. While abductor pollicis brevis and adductor pollicis, both attached to the extensor pollicis longus tendon, can extend the thumb's interphalangeal joint to the neutral position, only extensor pollicis longus can achieve full hyperextension at the interphalangeal joint.
The examiner pulls the thumb of the patient in ulnar deviation and longitudinal traction. If there is an increased pain in the radial styloid process and along the length of the extensor pollicis brevis and abductor pollicis longus tendons, then the test is positive for de Quervain’s syndrome.
The first compartment locating the most radial is occupied by the extensor pollicis brevis and the abductor pollicis longus to insert to the thumb. The second compartment is occupied by the two radial wrist extensors, the extensor carpi radialis longus and the extensor carpi radialis brevis.