Figure 4

Macroscopic analysis of the radial aspect of the trapeziometacarpal joint. The photographs in Fig. 3 show the radial aspect (right thumb). The layered relationships among the abductor pollicis brevis (APB), opponens pollicis (OPP), flexor pollicis brevis (FPB), and joint capsule are indicated. (a) the radial side of Fig. 3b. (b) the APB and abductor pollicis longus main tendon (APL-M) are removed from (a). The attachment of the APL-M to the first metacarpal bone (1st MC) is indicated by an asterisk. (c) muscular parts of the FPB and OPP are removed from (b). The radial capsule in the deep layer of the FPB and OPP is indicated by a dagger. FCR, flexor carpi radialis; APL-S, abductor pollicis longus–supernumerary tendon; Tm, trapezium; Dist, distal; Dors, dorsal; Ulna, ulnar.