Corpus: Interossei palmares muscles
from latin: palma palm; os - bone
Definition
The palmar interossei muscles are three short muscles that belong to the musculature of the palm of the hand. They are located volarly (on the palm side) in front of the dorsal interossei muscles.
Course
Origin
The palmar interossei muscles originate from the metacarpal bones according to the following scheme:
- Palmar interosseous muscle I: originates from the ulnar side of the metacarpal bone II
- Palmar interosseous muscle II: originates from the radial side of the metacarpal bone IV
- Palmar interosseous muscle III: originates from the radial side of the metacarpal bone V
Insertion
The short tendons of these muscles insert on the proximal phalanges and the dorsal aponeuroses of the fingers as follows:
- Palmar interosseous muscle I: inserts on the ulnar side of digit II
- Palmar interosseous muscle II: inserts on the radial side of digit IV
- Palmar interosseous muscle III: inserts on the radial side of digit V
Innervation
The innervation of the palmar interossei muscles is provided by the deep branch of the ulnar nerve from the brachial plexus (segments: C8 and Th1).
Function
The palmar interossei muscles are responsible for the adduction (drawing together) of the fingers at the metacarpophalangeal joints, thus acting antagonistically to the dorsal interossei muscles. However, both groups of muscles cause flexion at the metacarpophalangeal joints and extension at the proximal and distal interphalangeal joints.