The palmar interossei are intrinsic muscles of the hand. There are three palmar interossei muscles (although some texts describe a fourth muscle at the base of the proximal phalanx of the thumb). Attachments: Each interossei originates from a medial or lateral surface of a metacarpal, and attaches into the extensor hood and proximal phalanx of same finger. Actions: Adduction of the digits. Assists in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints. Innervation: Ulnar nerve. Blood Supply: Palmar metacarpal arteries By TeachMeSeries Ltd (2025) Fig 1The dorsal and palmar interossei of the hand. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Print Article Rate This Article