intricate muscles of the hand: midpalmar muscles

Question 1

Lumbricals

Answer 1

O: lateral side of each tendon of flexor digitorum profundus in palm
I: lateral edge of extensor expansion on proximal phalanx of fingers 2-5
N: median nerve and ulnar nerve
K: flex fingers at metacarpophalangeal joints but extend fingers at interphalangeal joints

Question 2

Palmar interossei

Answer 2

O: side of each metacarpal that faces the midaxis of the hand but absent from metacarpal 3
I: extensor expansion on first phalanx of each finger, on side facing midaxis of hand
N: ulnar nerve
K: adductor of fingers.

Question 3

Dorsal interossei

Answer 3

O: sides of metacarpals
I: extensor expansion over proximal phalanx of fingers 2-4 on side opposite midaxis of hand but on both sides of finger 3
N: ulnar nerve
K: abducts (diverge) fingers