Extensor Carpi Radialis Longus Muscle

The ECRL originates from the lower third of the lateral supracondylar ridge of the humerus. The ECRL inserts at the back of the base of the second metacarpal bone. The ECRL acts for extension and abduction of the hand at the wrist joint. This means extension and radial deviation of the hand at the wrist joint. In case of posterior interosseous nerve palsy, the extensor carpi radialis longus causes extension and radial deviation of the wrist.

In posterior interosseous nerve palsy, the extensor carpi ulnaris function is lost. The extensor carpi ulnaris is attached to the ulnar aspect of the fifth metacarpal bone, and it neutralizes the radial deviation effect of the extensor carpi radialis longus. The ECRL is innervated by the radial nerve (C6). The tendon of the ECRL is located at the second dorsal extensor compartment, and this tendon is implicated in insertion syndrome. Intersection Syndrome is pain felt on top of the forearm where two muscles that connect to the thumb cross over the underlying wrist tendons. The pain is located about 4 cm from the wrist joint. The two tendons of the wrist are the extensor carpi radialis longus and extensor carpi radialis brevis. The pain is increased by extension and flexion of the wrist (felt more on top of the forearm). Intersection syndrome pain is more proximal than the pain associated with De Quervain syndrome.

Author
Nabil Ebraheim, MD

You Might Also Enjoy...

Coracobrachialis Muscle Anatomy

The coracobrachialis muscle arises from the tip of the coracoid process. The coracobrachialis muscle may have a conjoint tendon with the short head of the biceps muscle. The coracobrachialis lies lateral to the pectoralis minor muscle.

Motions of the Thumb

The motions of the thumb are complex and are often difficult to visualize, as multiple joints and planes are involved. The motions are crucial to the overall function of the hand, with amputation of the thumb resulting in 40% impairment.