extensor digitorum brevis manus muscle
The extensor digitorum brevis manus (EDBM) muscle is an accessory muscle in the hand and is a normal anatomical variant.
Summary
- origin: distal radius and posterior radiocarpal ligament
- insertion: extensor hood of 2 or 3 digits (variable)
- innervation: posterior interosseous nerve
- action: extension of the digits
Epidemiology
It is thought to be present in ~3% of the population . It can be bilateral in up to half of cases.
Gross anatomy
The EDBM muscle lies along the ulnar side of the extensor tendon of the 2 digit (usually fourth wrist compartment ). It commonly arises at the distal end of the radius and posterior radiocarpal ligament to insert most commonly on the 2 digit. However, insertion can also be seen on the 3, 4, or 5 digits, as well as multiple insertions on more than one digit.
Arterial supply
- pending
Innervation
Clinical presentation
The muscle is usually painless although rarely it can present as a painful mass over the dorsal aspect of the hand. Occasionally it may be associated with exercise-induced pain or tenosynovitis of the extensor tendons.
Radiographic features
Plain radiograph
Can be normal.
Ultrasound
Sonography may reveal a soft-tissue mass with muscle echotexture; in real time, it usually undergoes morphologic changes during active finger extension.
MRI
Signal characteristics include:
- T1/T2/PD: isointense to muscle on all sequences
- C+ (Gd): no enhancement in uncomplicated cases (e.g. unless there is inflammation)
Siehe auch:
Assoziationen und Differentialdiagnosen zu extensor digitorum brevis manus muscle: