Extensor Digitorum

The Extensor Digitorum is sometimes simply referred to as Extensor Digitorum Communis and is one of the extensor muscles of the wrist, found in the forearm.

Anatomy of the Extensor Digitorum

It is innervated by the Posterior interosseous nerve and divides below into four tendons, which pass, together with that of the Extensor indicis proprius, through a separate compartment of the dorsal carpal ligament, within a mucous sheath.

The tendons then diverge on the back of the hand, and are inserted into the second and third phalanges of the fingers in the following manner.

The tendon to the index finger is accompanied by the Extensor indicis proprius, which lies on its ulnar side.

On the back of the hand, the tendons to the middle, ring, and little fingers are connected by two obliquely placed bands, one from the third tendon passing downward and lateral-ward to the second tendon, and the other passing from the same tendon downward and medial-ward to the fourth.

Occasionally the first tendon is connected to the second by a thin transverse band.

Functions of the Extensor Digitorum

The Extensor digitorum extends the phalanges, then the wrist, and finally the elbow.

It tends to separate the fingers as it extends them.

You will normally use the muscle when pulling the hand back and straightening the fingers to wave

The muscle can be strengthened by exercises that include the wrist extensor stretch and wrist extension with a resistance band.

As with most wrist extensors, you are likely to suffer from tennis elbow in the muscle.

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