Figure 10.19 (A) Anterior view of the forearm extrinsic finger flexors. (B) Anterior view displaying the flexor digitorum and flexor pollicis longus with a resected flexor digitorum superficialis.
TABLE 10.1 Extrinsic Hand Muscles Ventral Muscle Group
tunnel 3, which extends all the joints of the thumb and assists with wrist extension. Figure 10.22 illustrates the dorsal and palmar extrinsic muscles of the thumb. The tendons of the extensor digitorum and extensor indicis travel through tunnel 4. The extensor digitorum attaches proximally as part of the extensor tendon on the lateral humerus. The extensor digitorum tendons cross the wrist and course toward each of the digits before inserting distally on digits 2 through 5. Dorsal to the MCP joints, the extensor digitorum tendons are interconnected by thin strips of connective tissue called juncturae tendin- eae. These strips stabilize the position of the tendons as they approach the fi ngers. Contracting the extensor digitorum muscle extends all four of the digits. Because the muscle also crosses the wrist, it can assist with pro- ducing wrist extension. The extensor indicis also extends the joints of the second digit. Tunnel 5 contains the extensor digiti minimi that extends the fi fth digit. The extensor indicis and digiti minimi can also assist with
