Anatomic and clinical studies of the extensor digitorum brevis manus.

The extensor digitorum brevis manus muscle (EDBM) was found in 17 (3.0%) out of 559 dissected hands of 286 cadavers. The anatomy of the EDBM was classified into three types. The EDBM frequently arose on the distal margin of the radius, but without direct attachment to the carpal bones. The insertion of the EDBM was the same as that of the extensor indicis proprius. The EDBM and the extensor indicis proprius were often joined and had the same nerve and arterial supply. The EDBM muscle was considered to be a variant of the extensor indicis proprius muscle. Clinically five of 29 patients with an EDBM were treated.