Dorsal Interossei
The structure indicated is the
first dorsal interosseous muscle of the hand.
The
dorsal interossei belong to the
intrinsic group of muscles which act on the hand. The intrinsic muscles include the following muscles/groups:
- Thenar group (act on thumb)
- Hypothenar group (act on little finger)
- Adductor pollicis
- Lumbricals
- Interossesus muscles (dorsal and palmar)
- Palmaris brevis
All the intrinsic muscles of the hand, except the thenar muscles and the lateral two lumbrical muscles are innervated by the
deep branch of the ulnar nerve. The thenar muscles and the lateral two lumbrical muscles are innervated by the
median nerve. A useful mnemonic for remembering this is MEATLOAF. “
MEAT” refers to the
Median nerve, and
LOAF refers to the muscles which it innervates:
Lateral two lumbricals,
Opponens pollicis,
Abductor pollicis brevis,
Flexor pollicis brevis.
The
interosseous muscles, as the name suggests are located between (inter-) the metacarpal bones (-osseus). There are
4 bipennate dorsal interossei located between the adjacent shafts of the metacarpal bones and insert onto the bases of the proximal phalanges and the extensor hoods. The dorsal interossei serve to
abduct the fingers away from the central axis of the middle finger. The first interosseous muscle inserts onto the base laterally on the index finger.
The
palmar interossei in contrast are
unipennate in structure and function to
adduct the fingers towards the central axis of the middle finger. A useful mnemonic for remembering this function is PAD and DAB:
Palmar interossei
AD-duct,
Dorsal interossei
AB-duct.
Learn more about the anatomy of the
hand muscles in this tutorial.
