Which muscles assist with wrist extension?

Wrist extension is primarily facilitated by muscles that are located on the dorsal or posterior aspect of the forearm. The extensor indicis and extensor carpi radialis longus are two such muscles that play a significant role in this action.

The extensor carpi radialis longus originates from the lateral supracondylar ridge of the humerus and inserts into the base of the second metacarpal. Through its action, it extends and abducts the wrist. The extensor indicis, on the other hand, originates from the distal ulna and assists in extending the wrist while also extending the index finger. Together, these two muscles contribute effectively to wrist extension, making this answer correct.

In contrast, the other options contain muscles that do not primarily contribute to wrist extension. For instance, the flexor digitorum superficialis and flexor carpi ulnaris are involved in wrist flexion rather than extension. Palmaris longus and abductor pollicis brevis also focus on wrist flexion and thumb abduction, respectively. Finally, the flexor pollicis longus and flexor carpi radialis also do not assist in wrist extension; they primarily facilitate wrist flexion or thumb flex