Chapter 4 The Skeletal System 145 The wrist includes eight carpal (KAR-pal) bones that are roughly arranged in two rows (Figure 4.23). The carpal bones are bound together by ligaments that allow a small amount of gliding motion at the intercarpal joints. However, the main function of the carpals is to provide a base for the bones of the hand. Five metacarpal (meht-a-KAR-pal) bones in each hand articulate with the carpal bones in each wrist. There are 14 phalanges (fa-LAN-jeez)—the bones in the fingers. Each of the four fingers has proximal, medial, and distal phalanges, but the thumb has only two. At the distal (lower) ends of both the radius and ulna are styloid (STIGH-loyd) processes that are easy to see and feel with your fingers. The distal end of the radius unites with several of the carpal bones of the wrist to form the radiocarpal (ray-dee-oh-KAR-pal) joint (Figure 4.22). The Wrist and Hand Collectively, the wrists and hands contain 54 bones—27 on the left and 27 on the right. This large number of bones enables a wide range of precise movements, along with the important ability to grasp objects. © Body Scientific International Figure 4.21 Anterior and posterior views of the radius and ulna. Which of these two bones allows your forearm and hand to rotate freely? Head of ulna Ulnar notch of radius Anterior view Posterior view Olecranon Articular facets Styloid process Radial tuberosity Radial notch of ulna Trochlear notch Interosseous borders Ulnar tuberosity Coronoid process Radius Ulna Interosseous membrane Styloid process Styloid process Neck of radius Head of radius Head of radius Neck of radius Articulating Bones of the Arm and Wrist Joint Notched Bone Joining Bone humeroulnar (elbow) joint humerus ulna radioulnar joints (proximal and distal) radius ulna radiocarpal (wrist) joint radius three carpal bones Figure 4.22 Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co., Inc.