Hand and Blood Supply to Upper Limb

Hand and Blood Supply to the Upper Limb

Palmar Fascia and Flexor Sheaths

The palmar aponeurosis is a triangular thickening of deep fascia whose apex is attached to palmaris longus (when present) and whose fingers extend to the flexor sheaths and skin of the palm. Dupuytren's contracture is fibrosis of the palmar aponeurosis causing progressive flexion deformity, most commonly of the ring and little fingers.

The fibrous flexor sheath (digital tendon sheath) forms osseofibrous tunnels for the flexor tendons of each finger. It has annular (A1–A5) and cruciate (C1–C3) pulleys that prevent bowstringing. The synovial flexor sheath lubricates the tendons: FPL has its own sheath; FDS and FDP share a common digital sheath (incomplete for digits 2–4 but continuous for digit 5 and thumb). The flexor retinaculum spans from scaphoid/trapezium laterally to pisiform/hamate medially, forming the carpal tunnel roof. Carpal tunnel contents: FDS (×4), FDP (×4), FPL, and the median nerve. Carpal tunnel syndrome: compression of median nerve → pain/paraesthesia in lateral 3.5 digits, wasting of thenar muscles (ape hand).

Intrinsic Hand Muscles

Thenar eminence (opponens pollicis, flexor pollicis brevis, abductor pollicis brevis — all median nerve except deep head FPB = ulnar). Hypothenar eminence (opponens digiti minimi, flexor digiti minimi, abductor digiti minimi — all ulnar). Lumbricals (4): originate from FDP tendons, insert into extensor hood (lateral bands); flex MCP joints and extend IP joints; medial 2 = ulnar nerve, lateral 2 = median nerve. Interossei: dorsal interossei abduct (DAB, dorsal abduct); palmar interossei adduct (PAD, palmar adduct); both flex MCP and extend IP joints via extensor hood (all ulnar nerve).

Blood Supply to Upper Limb

Subclavian artery → axillary artery (at lateral border of 1st rib) → brachial artery (medial arm, bifurcates in cubital fossa) → radial artery (lateral) + ulnar artery (medial). In the hand: superficial palmar arch (mainly ulnar artery, completes with radial superficial branch) → common palmar digital → proper palmar digital arteries. Deep palmar arch (mainly radial artery entering via anatomical snuff box, completes with ulnar deep branch) → palmar metacarpal arteries, princeps pollicis, radialis indicis. Allen's test assesses collateral supply between radial and ulnar arteries.