Extensor carpi radialis longus

Longus is a separate muscle

Extensor carpi radialis longus and brevis are separate muscles with similar wrist actions, not two heads of one muscle. This page selects the longus mesh.

Use the name and source identifier to distinguish them. Shape alone can be misleading when the camera angle or zoom changes.

Sources: Longus anatomy · Brevis comparison

Above the lateral epicondyle to metacarpal II

ECRL begins on the lower part of the humerus’s lateral supracondylar ridge and the adjacent lateral intermuscular septum. Its tendon attaches to the dorsal base of the second metacarpal.

Despite the word radialis, the distal attachment is in the hand, not on the radius. Neither that metacarpal nor the humerus is loaded here.

Sources: Longus anatomy

Extension with radial deviation

ECRL helps bend the wrist toward the back of the hand and move it toward the thumb side. These are wrist extension and radial deviation, respectively.

The hand and wrist bones are not loaded here. Camera rotation changes the view, not wrist position; this model does not simulate contraction, tendon gliding or a range of motion.

Compare the companion brevis guide to separate a shared action from a shared attachment: the two muscles have different metacarpal destinations.

Sources: Longus anatomy · Brevis comparison

Radial-nerve and arterial connections

The radial nerve supplies ECRL. Radial recurrent arterial branches contribute to its blood supply.

Nerves and vessels are not loaded in this subset, so the text describes connections you cannot select in the viewer.

Sources: Forearm anatomy study

Read the model

Explore extensor carpi radialis longus in 3D

1. Follow the longus mesh. Inspect it alone first. Use Front, Back and Oblique to compare the same structure from different angles.
2. Switch between the radial extensors. Choose Show context, then alternate Extensor carpi radialis longus and Extensor carpi radialis brevis. Gold follows the selected muscle; it does not indicate which muscle is contracting.
3. Keep the endpoint limitation in mind. The hand bones are absent, so the second-metacarpal insertion described in the article cannot be checked against a loaded bone.

Sources and editorial status

This guide uses independently written explanations with links to the evidence behind them. Source checking and specialist anatomical review are separate steps; the latter is still pending.

1. Loyola University Chicago — LUMEN, Extensor carpi radialis longus

   Supracondylar and septal origin, second-metacarpal insertion, wrist actions and radial-nerve supply.

2. Loyola University Chicago — LUMEN, Extensor carpi radialis brevis

   Comparison of brevis attachments and actions with longus.

3. Anatomy of the nerves, vessels, and muscular compartments of the forearm, as revealed by high-resolution ultrasound. Part 1 (2021)

   Table 2: nerve and arterial supply of the forearm compartments. No ultrasound images are reproduced.

3D geometry and its separate license are credited beneath the viewer. References do not imply endorsement of this site.