The wrist is one of the most complex joints in the body, comprised of multiple small bones and joints and capable of multiple degrees of freedom, according to eOrthopod. The anatomy of the wrist is complicated because its structure supports the functionality required to give the hand a full range of complex motion and the dexterity for a strong grip.
The wide range of motion of the hand is due to the bones, ligaments and supporting structures in the wrist, explains eOrthopod.The wrist contains eight small carpal bones divided into two rows. The proximal row of bones, comprised of the scaphoid, lunate and triquetrum, connects the radius and ulna to the metacarpals in the hand. The distal row of bones contains the trapezium, trapezoid, capitate, hamate and pisiform bones and is located closer to the fingers. The wrist is supported by two important ligaments called the collateral ligaments, which help to form a joint capsule around the eight carpal bones.
The ulnar collateral ligament and the radial collateral ligament connect the forearm to the wrist and prevent the wrist from bending too far in either direction, states eOrthodpod. Flexor and extensor tendons connect muscle to bone and are responsible for helping to bend the wrist and curl the fingers and thumb. These tendons originate in the forearm. Three nerves that innervate the hand begin as a bundle in the shoulder and cross through the wrist. The radial, median and ulnar nerves carry motor signals to the muscles in the wrist and hand, and carry sensory signals back to the brain. Large blood vessels such as the radial and ulnar arteries travel alongside the nerves to supply the hand with blood.