Function

  Wrist

  The wrist connects the radius and ulna to the metacarpals. It should provide a stable, mobile, pain-free platform on which the hand can function. It comprises eight bones — scaphoid, trapezium, trapezioid, capitate, hamate, triquetral, pisiform and lunate. A complex system of intrinsic and extrinsic ligaments maintains the alignment of these bones and co­ordinates their movement, whilst the long flexor and extensor tendons contract across them.

  Hand

The hand is a very intricate tool with which the individual can receive information from the outside world and then act upon it. It must be supple, sensate, pain-free and co­ordinated. There are several types of grip. The thumb acts as a post against which the index finger moves for fine pinch (picking up a pin). The little and ring fingers curl into the palm to provide power grip (holding a hammer). The thumb moves to the side of the index finger for key grip and to the tips of the index and middle fingers for chuck grip (holding a pen). All of the fingers curl for hook grip (holding a suitcase).