The forearm constitutes the anatomical adaptation most likey responsible for the advancement of human intelligence. Intelligence would be sorely handicapped without the dexterity contained in the forearm and hand. Furthermore, the combination of intelligence and manual dexterity renders humans more capable of survival than any other animal species. It could also, however, be the means to our demise.

The forearm has many muscular functions involving the movement of the wrist and hand. Large powerful muscles operate the wrist and hand in performing movements requiring strength such as gripping a hammer or grasping a heavy pair of garden shears. These large powerful muscles are located in the forearm where they can best perform actions involving strength. Imagine your glove size if these muscles were located in the hand.

With the muscles of strength located in the forearm, the smaller muscles performing the more delicate digital movements can be located within the hand.

Pronation and supination are other movements of the forearm. These movements occur when the proximal radius, rotating in the radial notch of the ulna, and the distal radius, rotating about the distal end of the ulna, bring about the action of turning the forearm. Because the radius is curved, the rotary motion results in the anterior facing forearm becoming the posterior facing forearm (pronation). Untrained observaion may result in the conclusion that this movement appears to be occurring at the wrist with the hand rotating about the forearm. It is even more interesting that supination is orchestrated primarily by the biceps brachii located in the arm.

At the wrist or radiocarpal joint, the radius articulates with the scaphoid and lunate. The ulna has very little involvement with the carpals. Injuries resulting from a fall on outstretched hands (FOOSH) often leave the scaphoid or radius broken.