The clinical anatomy of commonly injured muscle bellies.

Injury to a skeletal muscle belly resulting in discontinuity of the muscle fibers is an infrequent but serious occurrence. Early surgical treatment of these injuries may prevent healing of the muscle in a lengthened position. Cadaver specimens of commonly injured muscles of the upper and lower extremities were examined for the presence, location, and extent of the tendons of origin and insertion. Most of the muscle bellies contained tendinous extensions that appeared as flattened fibrous bands. Optimal surgical repair of a muscle belly injury should include re-establishing the continuity of any intramuscular tendinous extensions. This study provides anatomic information as to the approximate location and extent of these tendons to permit optimal repair. In general, operative repair of the tendinous portion within a muscle belly is possible in the proximal third and distal thirds of most muscles, and in the middle third of a few muscles.