Flexor Digitorum Profundus Muscle, Anterior View

Description

Anterior forearm anatomy is presented with the flexor digitorum profundus (FDP) emphasized as a broad, deep muscle belly occupying much of the volar compartment. From its proximal attachments along the anterior and medial surfaces of the ulna and the adjacent interosseous membrane, the muscle fibers course distally and give rise to four tendons that pass deep to flexor digitorum superficialis, continuing toward digits II to V. Medial to the radius, the FDP lies deep to the more superficial flexor-pronator mass, and it tracks into the carpal tunnel region beneath the flexor retinaculum. Deep plane. FDP matters because it is the only long flexor that reliably produces flexion at the distal interphalangeal joints, a key teaching point when isolating finger flexion on physical exam. Its intimate relationship with the anterior interosseous nerve in the deep forearm explains why anterior interosseous nerve syndrome can present as weak thumb interphalangeal flexion and weak index (and sometimes middle) finger DIP flexion, classically affecting flexor pollicis longus and the radial portion of FDP. Surgeons and hand therapists also care about the tendon anatomy, since zone II flexor tendon lacerations and adhesions can limit independent DIP motion even when the superficialis tendon remains intact. Use this artwork in upper limb dissection lab guides, hand and wrist biomechanics lectures, and exam-prep materials that distinguish FDP from flexor digitorum superficialis by depth and joint action. It also fits operative atlases and patient-facing education on flexor tendon repair, anterior forearm nerve entrapment, and rehabilitation goals after volar forearm injuries. Anatomical accuracy verified by SciePro's Medical Advisory Board.