Flexor Digitorum Profundus, Medial View

Description

Arising from the anterior and medial surfaces of the ulna and the adjacent interosseous membrane, the flexor digitorum profundus occupies the deep layer of the anterior compartment of the forearm, shown from a medial perspective beneath the flexor digitorum superficialis. Its muscle belly lies anterior to the ulna, while the radius sits more lateral, and the tendon slips course distally toward the carpal region en route to the digits. Proximally, the elbow region is framed by the distal humerus articulating with the ulna and radius, with the shoulder represented by the humeral head superiorly. Depth is the point. A medial view clarifies why the profundus is the power source for flexion at the distal interphalangeal joints, and why its tendons remain clinically distinct from the superficialis within the digital flexor sheath. For hand surgeons and therapists, separating profundus from superficialis function underpins examination of jersey finger (avulsion of the flexor digitorum profundus tendon from the distal phalanx, classically the ring finger) and guides planning for tendon repair and rehabilitation protocols that protect the repair while preserving glide. The ulnar-sided origin also helps teach why ulnar nerve lesions can weaken intrinsic hand function and, in more proximal injury, compromise the ulnar-innervated portion of profundus to the ring and little fingers. Orthopaedic and gross anatomy faculty can place this plate alongside cross-sectional teaching to anchor the deep-to-superficial organization of the forearm flexors and the relationship of tendon paths to the carpus and phalanges. It also fits cleanly into surgical education materials on flexor tendon zones, pulley anatomy, and postoperative splinting rationales in hand therapy documentation. Anatomical accuracy verified by SciePro's Medical Advisory Board.