What is the wrist?

The wrist is a complex joint that connects the bones of the forearm to those of the hand. It allows flexion and extension movements of the hand. If the wrist is overused by chronic repetitive movements, it can lead to damage to it or even limiting movement possibilities.

The wrist is formed by bones hold together by ligaments and associated muscles and nerves which allow mobility. The structure itself is made up of the ulna and radius (two bones of the forearm) and the scaphoid bone and lunate bone (two carpal bones). In addition to this, there are also six other carpal bones, which are formed in two rows. The proximal row (the one nearest to the wrist) is formed by the triquetrum bone and the pisiform bone, while the distal row (the one farthest from the wrist) is formed by the trapezoid bone, trapezium bone, capitates bone and hamate bone. The navicular crosses both rows instead. Each of these bones is connected to the ones closest to it by means of one or more ligaments. Among these, the largest are the ulnar collateral ligament (medial ligament) and the radial collateral ligament (side ligament), respectively connecting the ulna at the triquetrum and pisiform bones and the radius at the scaphoid bone. 

The muscles that are used to move the wrist are located in the forearm. They include the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor digitorum (ED), extensor digiti minimi (EDM), extensor carpi ulnaris (ECU), abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis (EI). A single tendon connects them to the hand moving inside the wrist.Finally, three nerves originating from the forearm move cross the wrist to reach the hand. These include the radial nerve, which innervates the back of the hand in the area between the thumb and middle finger; the median nerve, which is divided into four bands to innervate the thumb and three higher fingers; and the ulnar nerve, which innervates the little finger and the outer half of the ring.

Common conditions associated with the wrist include carpal tunnel syndrome and osteoarthritis. Carpal tunnel syndrome refers to a medical condition that causes pain, numbness and tingling of the wrist. Osteoarthritis is a condition that causes joint destruction due to degeneration of cartilage and bone changes. In both cases, seeking medical assistance is essential in order to determine the most appropriate form of treatment and prevent symptoms from worsening.


What function does the wrist serve?

The wrist connects the forearm and hand, in turn allowing a wide range of movements. In particular, the wrist extensors allow the hand to be raised and wrist to be rotated. The wrist also allows other movements, specifically in the ulnar deviation (which involve the ulnar extensor and flexor carpi ulnaris) by allowing the hand to be turned to the outside; the radial deviation, which permits writing and the flexor carpi radialis and short/long radials, which allow the hand to be turned inward.

The anatomy of the wrist is extremely complex, though the group of bones and joints involved allow the hands to be used in a number of different ways. The wrist must be extremely mobile in order to give the hands full range of motion and at the same time, provide strength for heaving gripping and lifting.