chapter  45
28 Pages

Upper Extremity Analysis of the Wrist

The human hand has 27 bones divided into three groups: 8 carpal bones in the wrist, 5 metacarpal bones,

and 14 phalanges of the fingers. The carpal bones are arranged in two rows and have names reflecting

their shapes (Figure 45.1). The bones of the distal row, from the lateral side to the medial side,

include the trapezium (four sided with two parallel sides), the trapezoid (four sided), the capitate

(the central bone), and the hamate (hook shaped). These four bones fit together, tightly bound by inter-

osseous ligaments to form a relatively immobile unit that articulates with the metacarpals to form the

carpometacarpal (CMC) joint. The bones of the proximal row include the scaphoid (boat shaped),

the lunate (half-moon shaped), the triquetrum (triangle shaped), and the pisiform (pea shaped). The

proximal surfaces of the scaphoid, lunate, and triquetrum form a biconvex elliptical surface which articu-

lates with the biconcave surface of the distal extremity of the radius. The articulation between the prox-

imal and distal rows is term the midcarpal joint while articulations between adjacent bones are called

intercarpal joints.