The extensor digiti minimi is one of the muscles of the superficial layer of the posterior compartment of the forearm. It is an accessory extensor of the little finger.
The posterior compartment of the forearm consists of a superficial layer (7 muscles) and a deep layer (5 muscles).
The muscles in the superficial layer include:
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor digitorum
- Extensor digiti minimi
- Extensor carpi ulnaris
The muscles of the superficial layer share a common origin from the lateral epicondyle and lateral supracondylar ridge of the humerus.
All the muscles of the posterior compartment are innervated by the radial nerve.
The extensor expansion/hood is a triangular connective tissue aponeurosis on the dorsal surfaces of the middle and distal phalanges. The apex of th triangle attaches to the distal phalanx, the central parts attach to the middle phalanx and the corners of the triangle are wrapped around the sides of the metacarpophalangeal joints, attaching to the deep transverse metacarpal ligaments.
Several of the intrinsic muscles of the hand attach to the margins of the extensor hood on either side, reinforcing the structure.
The extensor expansion consists of 3 parts/slips:
Flexor digiti minimi brevis