Action: Flex the metacarpophalangeal joint, extend the proximal and distal interphalangeal joints of digits 2-4, abduct digits 2-4 (abduction of digits in the hand is defined as movement away from the midline of the 3rd digit)Origin - Four muscles, each arising from two adjacent metacarpal shaftsInsertion - Base of the proximal phalanx and the extensor expansion on lateral side of the 2nd digit, lateral & medial sides of the 3rd digit, and medial side of the 4th digitInnervation - Ulnar nerve, deep branch

1.
Action: Flex the metacarpophalangeal joint, extend the proximal and distal interphalangeal joints of digits 2-4, abduct digits 2-4 (abduction of digits in the hand is defined as movement away from the midline of the 3rd digit)
Origin - Four muscles, each arising from two adjacent metacarpal shafts
Insertion - Base of the proximal phalanx and the extensor expansion on lateral side of the 2nd digit, lateral & medial sides of the 3rd digit, and medial side of the 4th digit
Innervation - Ulnar nerve, deep branch

Opponens Pollicis
Tensor Fascia Lata
Peroneus (Fibularis) Brevis
Dorsal Interossei