Overview
In the cat it is described as two muscles, the extensor carpi radialis longus and brevis, each with its own belly and tendon crossing the dorsal surface of the carpus. In the dog it forms a single belly with two tendons.
Origin
Lateral supracondylar crest of the humerus.
Insertion
- Extensor carpi radialis longus: base of metacarpal bone II.
- Extensor carpi radialis brevis: base of metacarpal bone III.
Action
Extends the carpus.
Innervation
Radial nerve (n. radialis).
Clinical relevance
It is used in the neurological examination: tapping its belly extends the carpus (extensor carpi radialis reflex), which tests the radial nerve.