Extensor digiti minimi
Musculus extensor digiti minimi
Also known as: EDM, extensor digiti quinti
A slender muscle, often partly fused with extensor digitorum, that extends the little finger. It occupies its own (5th) extensor compartment.
Overview
EDM arises from the common extensor origin, usually as a partially separate slip of extensor digitorum. Its tendon passes through the 5th extensor compartment, over the distal radio-ulnar joint, and joins the extensor expansion of the little finger, usually on the ulnar side of the extensor digitorum tendon to that finger. Together with the often-deficient extensor digitorum slip to the little finger, it allows the little finger to be extended independently.
Anatomy
- Origin
Lateral epicondyle of the humerus (common extensor origin).
- Insertion
Extensor expansion of the 5th digit.
- Action
Extension of the little finger.
- Innervation
Posterior interosseous nerve.
- Nerve roots
C7–C8
- Arterial supply
Posterior interosseous artery.
Function
- Extends the little finger at the MCP and IP joints
- Assists wrist extension
Clinical significance
Vaughan-Jackson syndrome
In rheumatoid arthritis, erosion of the ulnar head causes attritional rupture of the extensor tendons, starting with EDM and then the extensor digitorum tendons to the ring and little fingers.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.