The second palmar interosseous (PAD: Palmar ADducts) adducts the ring finger toward the axis of the middle finger. It lies between the third and fourth metacarpals in the third web space and is the primary radial deviator of the ring finger, counterbalancing the fourth dorsal interosseous.
| Origin | Radial side of the fourth metacarpal (unipennate) |
|---|---|
| Insertion | Radial base of the proximal phalanx of the ring finger and extensor hood |
| Nerve Supply | Deep branch of the ulnar nerve (C8, T1) |
| Blood Supply | Second palmar metacarpal artery |
| Actions | Adducts the ring finger toward the middle finger axis; Assists MCP flexion of the ring finger |
|---|
The second palmar interosseous is assessed in ulnar nerve palsy alongside the dorsal interossei. Its denervation produces ring finger abduction deformity (the ring finger deviates radially due to unopposed third dorsal interosseous action). EMG needling of the second palmar interosseous targets the third interosseous space. In Dupuytren's disease affecting the ring finger, the palmar interosseous may be incorporated in the cord.
Palpated in the third web space on the palmar surface during resisted ring finger adduction toward the middle finger.
Ulnar nerve denervation of the second palmar interosseous producing ring finger radial deviation and weakness of MCP flexion with IP extension, requiring intrinsic rebalancing in chronic cases.
