Oblique Head of the Adductor Pollicis Muscle, Anterior View

Description

Arising from the capitate and the bases of the second and third metacarpals, the oblique head of adductor pollicis is rendered on the palmar (anterior) aspect of a male hand, lying deep in the central palm and running distally and laterally toward the thumb. Its muscle fibers converge into a tendon that passes to the ulnar side of the first metacarpophalangeal joint, blending with the medial sesamoid and inserting on the ulnar base of the proximal phalanx of the thumb. Surrounding skeletal landmarks include the carpal bones in two rows, the metacarpals aligned from radial to ulnar, and the proximal, middle, and distal phalanges, with the thumb shown in its two-phalange configuration. Blue articular surfaces mark the carpal, carpometacarpal, metacarpophalangeal, and interphalangeal joints for orientation. Palmar exposure is the point here because adductor pollicis sits in the deep thenar compartment, where it forms the muscular bulk that draws the thumb toward the index metacarpal during pinch. Weakness of thumb adduction is a practical exam finding in ulnar nerve palsy, and the adductor pollicis is the muscle tested with Froment sign when patients compensate with flexor pollicis longus. The insertion adjacent to the sesamoid complex also explains why pathology around the thumb MCP joint can alter adduction mechanics and pinch stability. Hand anatomy courses and surgical teaching files can use this plate to anchor deep palmar muscle layering against fixed bony landmarks, from capitate to first metacarpal and proximal phalanx. It also suits clinical education on ulnar neuropathy at Guyon canal and motor testing of intrinsic hand muscles in rehabilitation and neurology texts. Anatomical accuracy verified by SciePro's Medical Advisory Board.