Distribution of the extensor tendons on the dorsum of the hand

The patterns of the tendons of extensor digiti minimi, extensor digitorum, and extensor indicis have been studied on the dorsum of the hands of 25 embalmed cadavers. Each of the tendons of extensor digitorum (ED) is usually single, but those of the middle and ring fingers are occasionally multiple. Intertendinous connections are of variable pattern. The ED tendon of the little finger lies closely to that of the ring finger, with which it may be fused, or it may be absent. It is suggested that it may be undergoing evolutionary reduction. Extensor digiti minimi (EDM) usually has two tendons, but may have three or four. In addition to EDM, the little finger also receives either a separate tendon, or a tendinous slip, from ED. Extensor indicis (EI) varies in the number of its tendons, in its position relative to the ED tendon to index finger, and in its connection to extensor pollicis longus tendon. Examples of supernumerary muscles (extensor digitorum brevis manus, extensor indicis brevis, and extensor pollicis et indicis communis) were also found.