Extensor Carpi Radialis Longus
|Origin||Lateral epicondyle of the humerus and ridge immediately above.|
|Insertion||Dorsal surface of base of the second metacarpal.|
Extensor carpi radialis longus is sometimes grouped with brachioradialis, and together are called the spiral muscles of the arm. Both muscles originate on the lateral side of the distal end of the humerus, wrap around to the palm side of the forearm, and insert along the radial side of the wrist. This is a good way of regarding them when the arm is straightened or relaxed.
But the tensed brachioradialis rises away from carpi radialis longus, and a sharp angle forms between them. Brachioradialis seems to align with biceps, another flexor, and the division between them and their neighboring extensors is clear.