Name

# Palmar Interossei

Pronunciation

(PALM-er in-ter-OSS-E-I)

Origin/Proximal Attachment

From the side of the metacarpal that faces the midline

Insertion/Distal Attachment

On the base of the proximal phalanx of the digit of origin (same side toward the midline); extensor hood of the same digit/s

Action/Relevance

Adducts the fingersFlexes the fingers (at the MCP while IP joints are extended)

Innervation

Ulnar nerve - deep branch (C8, T1)

Notes

The palmar interossei muscles are a group of four muscles located between the metacarpal bones. Relative to the dorsal interossei, they reside in a more superficial layer relative to the palmar surface.

The palmar interossei arise from the ulnar side of the 1st and 2nd metacarpals and the radial side of the 4th and 5th metacarpals. Each muscle independently inserts into the base of the proximal phalanx and extensor expansion of the same digit. The exception is the first palmar interosseous which inserts into the ulnar sesamoid bone of the thumb.