First palmar interosseous muscle

Origin: Metacarpals

Insertion: Proximal phalange

Nerve: Deep branch of ulnar nerve

Action: Adduction

Description:
The Palmar Interossei, three in number, are smaller than the Interossei dorsales, and placed upon the volar surfaces of the metacarpal bones, rather than between them. Each arises from the entire length of the metacarpal bone of one finger, and is inserted into the side of the base of the first phalanx and aponeurotic expansion of the Extensor communis tendon to the same finger.

• The first arises from the ulnar side of the second metacarpal bone, and is inserted into the same side of the first phalanx of the index finger.
• The second arises from the radial side of the fourth metacarpal bone, and is inserted into the same side of the ring finger.
• The third arises from the radial side of the fifth metacarpal bone, and is inserted into the same side of the little finger. From this account it may be seen that each finger is provided with two Interossei, with the exception of the little finger, in which the Abductor takes the place of one of the pair.