Muscle
Palmar interossei
Draw the fingers back toward the middle-finger axis
High-yield
Palmar interossei bring fingers together. The middle finger needs no matching adductor because it defines the reference axis.
Overview
Three palmar interossei are usually described for the index, ring and little fingers. Each pulls its finger toward the middle-finger axis and helps coordinate the knuckle and interphalangeal joints.
Reference facts
- Origin
- Second metacarpal on its ulnar side; fourth and fifth metacarpals on their radial sides
- Insertion
- Same-sided proximal phalangeal bases and extensor expansions of digits 2, 4 and 5
- Action
- Draw digits 2, 4 and 5 toward the middle finger; assist MCP flexion and IP extension
- Innervation
- Deep ulnar nerve branch, mainly C8–T1
- Blood supply
- Branches of the palmar metacarpal arteries
Clinical correlation
Ulnar nerve dysfunction can weaken finger adduction. A little finger that remains spread outward is called Wartenberg's sign; it is one finding within a broader nerve examination.
Frequently asked questions
What do the palmar interossei do?
Draw digits 2, 4 and 5 toward the middle finger; assist MCP flexion and IP extension.
What nerve innervates the palmar interossei?
Deep ulnar nerve branch, mainly C8–T1.
Where do the palmar interossei attach?
Origin: Second metacarpal on its ulnar side; fourth and fifth metacarpals on their radial sides. Insertion: Same-sided proximal phalangeal bases and extensor expansions of digits 2, 4 and 5.
What is the blood supply of the palmar interossei?
Branches of the palmar metacarpal arteries.