What is the anatomy of the hand and wrist?
The distal radius and ulna articulate with the proximal row of carpal bones, although the ulna does not articulate directly but is separated by the articular disc of the triangular fibrocartilage complex (TFCC). The proximal carpal row consists of scaphoid, lunate, triquetrum, and pisiform bones. The distal carpal row consists of the trapezium, trapezoid, capitate, and hamate bones.
The distal carpal row articulates with the bases of the metacarpal bones, which in turn articulate with the proximal phalanges. In the thumb, there are only two (proximal and distal) phalanges joined at the interphalangeal (IP) joint, whereas in the remainder of the digits there are three phalanges (proximal, middle, and distal) joined by the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints.
The ligaments of the wrist consist of both the intrinsic ligaments, which extend between the bones of the proximal carpal row, and the extrinsic ligaments, primarily on the volar and dorsal surface of the wrist, which extend over much greater distances, often crossing the radiocarpal and carpometacarpal articulations. The extrinsic ligaments provide the overall stability of the wrist, whereas the intrinsic ligaments maintain the relationship of the bones of the proximal row.
Multiple tendons cross the dorsal surface of the wrist, contained within six separate compartments. As they extend onto the dorsal surface of the fingers, the tendons divide up in a complex pattern to form the dorsal “hood.” The flexor tendons cross the wrist on the volar surface within the carpal tunnel and exit onto the fingers as the deep and superficial flexor tendons, where they are held close to the bone by a series of fibrous pulleys.