The extensor pollicis longus is a muscle located in the forearm. The primary action of the muscle is to help extend the wrist as well as the thumb during a variety of different activities. Visually it’s possible to see the muscle at the bottom of the thumb. It is a much bigger muscle than its cousin the extensor pollicis brevis.
The origin of the extensor pollicis longus is on the ulna, which is a bone in the forearm. From around halfway between the elbow and the wrist, the muscle begins and then runs down the arm and up through the thumb before attaching to the distal phalanx. Its innvervation is from the posterior interosseous nerve. The antagonists of the muscle are the flexor pollicis longus and flexor pollicis brevis which help to counteract its movements.
The extensor pollicis longus muscle is long and thin in shape. At the base of the thumb, however, it forms a triangle shape in between two different tendons. The muscle starts off thicker and becomes thinner as it travels down the arm before entering the thumb. To view the extensor pollicis longus a person must look on the wrist’s radial side.
The muscle's main action is to extend the distal phalanax, which are the tips of the fingers. For this reason it is used in any activity which requires letting go of an object. Along with the extensor pollicis brevis the muscle is also used in extension of the wrist. It also helps in wrist adduction.
There are several other extensor muscles located in the wrist and forearm. For example, the extensor carpi radialis muscles and extensor carpi ulnaris are all used to control movements of the wrist and hand. Together with the extensor pollicis longus, these muscles make a variety of movements possible and help to provide the stability and function needed for small and accurate actions.
The extensor pollicis longus tendon is prone to problems because it is so regularly used. Tendinitis of the extensor pollicis longus is a relatively common and painful condition. As with all types of tendinitis, the initial stages of recovery are usually aided by resting and icing the affected area. Often the problem is caused by overuse and hence avoiding the action which caused the tendon to become inflamed is essential for a full recovery. More serious occurrences of extensor pollicis longus tendinitis may require additional treatment.
