Central muscles of the hand

Lumbricals 1-2

Digtal branch of median nerve (C8-T1)
O: lateral sides of 1st and 2nd tendons of FDP
I: lateral sides of proximal phalanges and extensor hoods of index and middle fingers

Lumbricals 3-4

Deep branch of ulnar nerve (C8-T1)
O: medial side of 2nd tendon and adjacent sides of 3rd, lateral side of 4th tendon of FDP
I: lateral sides of proximal phalanges and extensor hood of ring and little

Lumbricals movement

MCP joint flexion and IP joint extension
Positions MCP joints for writing
Takes tension off the flexor tendons during finger extension

Adduction pollicis

Deep branch of ulnar nerve (C8-T1)
O: transervse head (lateral shaft of 3rd metacarpal) oblique (capitate and bases of 2nd a nd 3rd metacarpals)
I: base of proximal phalanx of thumb

Adductor polliics action

Thumb adduction

Palmar interossei

Anterior to dorsal interossei (unipennate)

1st palmar interosseuous

Deep branch of ulnar nerve (C8-T1)
O: medial side of shaft of 2nd metacarpal
I: medial side of proximal phalax and extensor expansion of index finger

2-3 palmar interossei

Deep branch of ulnar nerve (C8-T1)
O: lateral side of shafts 4 and 5 metacarpals
I: lateral side of proximal phalanx and extensor expansion of ring and little finger

Palmar interossei action

Adduction of index, fing and little

Dorsal interossei

Posterior to palmar interossei (bipennate)

1-2 dorsal interossei

Deep branch of ulnar nerve (C8-T1)
O: medial side of 1, adjacent sides of 2, and lateral side of 3rd metacarpal
I: lateral side of proximal phalanx and extensor expansion of index and middle fingers

3-4 dorsal interossei

Deep branch of ulnar nerve (C8-T1)
O: medial side of 3rd, adjacent sides of 4 and lateral side of 5
I: medial side of proximal phalanx and extensor expansion of middle and ring fingers

Dorsal interossei action

Abduction of index, middle and ring