Your Wrist & Hand
The structure and function of the hand is unique to Homo sapiens. This is because the thumb is positioned in the hand so that it can appose to the other four fingers. This then allows humans to manipulate their environment in the effective manner that they do. This manipulative ability is complimented by the fact that humans stand on their two lower limbs and probably developed as a result of Man's ability to stand upright. Each finger consists of three bones called phalanges that are activated by flexor and extensor tendons. The thumb consists of two phalanges again activated by flexor, abductor and extensor tendons. The wrist consists of eight bones ( scaphoid, lunate, triquetrum, pisiform, hamate, capitate, trapezoid and trapezium - starting and ending on the thumb side) that are arranged so that the wrist can transmit forces to the forearm and upper arm. The wrist functions best in the transmission of forces when in a position of extension that is approximately 20-30°. Its function is to act as a platform for the thumb and fingers of the hand.
