What is the primary action of the flexor carpi radialis?

• A. Flex carpus
• B. Extend carpus
• C. Abduct manus
• D. Rotate forearm

Answer: (A)

The flexor carpi radialis muscle primarily functions to flex the wrist (carpus). It is located in the anterior compartment of the forearm and acts to bend the wrist towards the anterior side of the body. This muscle's path, running from the medial epicondyle of the humerus to its insertion on the base of the second and third metacarpal bones, facilitates this flexion action effectively.

While the other options mention actions like extending, abducting, and rotating, these do not represent the primary function of the flexor carpi radialis. Instead, they correspond to other muscles or muscle groups responsible for those movements. For instance, extending the wrist involves the extensor muscles on the posterior aspect of the forearm, and abducting the hand involves muscles such as the abductor pollicis longus and abductor digiti minimi. Rotation of the forearm is primarily facilitated by the pronator teres, supinator, and other specific muscles designed for pronation and supination.