Digital artery

The digital arteries are the terminal branches of the hand's arterial system that supply the fingers. They are divided into common digital arteries and proper digital arteries. These arteries deliver oxygenated blood to the palmar and dorsal surfaces of the fingers, playing a vital role in the vascular supply to the digital skin, tendons, joints, and nail beds. Their integrity is essential for hand function, tissue viability, and thermal regulation.

Classification

Location

• Common digital arteries: Travel in the palm over the flexor tendons, between the metacarpal bones, and divide into proper digital arteries near the base of the fingers.
• Proper digital arteries: Run along the medial and lateral sides of each finger. Each finger is supplied by a pair of proper digital arteries.
• Dorsal digital arteries: Found on the dorsal side of the fingers and supply the proximal phalanges and nail beds. Their supply is often supplemented by perforating branches from the palmar side.

Origin and Course

Palmar Digital Arteries

• The superficial palmar arch, primarily derived from the ulnar artery, gives rise to three common palmar digital arteries.
• Each common palmar digital artery bifurcates near the web spaces to form two proper palmar digital arteries.
• These proper branches run along the sides of the index, middle, ring, and little fingers.
• The radial artery contributes to the thumb and lateral index finger through the princeps pollicis artery and radialis indicis artery.

Dorsal Digital Arteries

• The dorsal metacarpal arteries, arising from the dorsal carpal arch, divide into dorsal digital arteries which supply the dorsum of the fingers.
• These are generally limited to the proximal phalanges, as the distal parts of the dorsum of the fingers are supplied by palmar digital artery perforators.

Function

• Oxygenation: Provide oxygen and nutrients to the skin, connective tissue, and nail beds of the digits.
• Thermoregulation: Play a key role in heat conservation and dissipation through vasodilation and vasoconstriction.
• Collateral circulation: Digital arteries form anastomotic loops at the level of each phalanx to ensure continuous perfusion even under stress or compression.

Physiological Role(s)

• Enable fine tactile function through adequate perfusion of mechanoreceptors in the skin.
• Maintain tissue viability during cold exposure and vascular stress by participating in arteriovenous shunting.
• Support rapid healing and inflammation control in case of digital trauma or infection.

Relations

• Palmar digital arteries: Accompanied by digital nerves and veins in neurovascular bundles located on each side of the finger.
• Located superficial to the flexor tendons and deep to the skin and fibrous digital sheaths.
• Dorsal digital arteries: Run in the subcutaneous tissue over the extensor tendons, typically less robust than palmar vessels.

Development

Digital arteries form from the remodeling of primitive capillary plexuses in the embryonic limb bud. Vascular branching is guided by limb patterning genes and coordinated with nerve development. The radial and ulnar arteries extend into the hand and create the palmar arches, from which digital vessels sprout. Maturation includes the formation of anastomotic arcades and thermoregulatory structures like glomus bodies.

Clinical Significance

• Raynaud’s disease: Hyperreactivity of digital arteries to cold or stress causes episodic digital ischemia and pallor, often with pain or numbness.
• Digital ischemia: Trauma, embolism, or vasculitis may compromise these arteries, leading to tissue necrosis if not treated.
• Frostbite: Digital arteries are extremely vulnerable to freezing injury due to their small size and peripheral location.
• Peripheral artery disease (PAD): Rarely, PAD may extend distally and affect digital perfusion, especially in diabetic patients or smokers.
• Allen test: Used to evaluate collateral flow from ulnar and radial arteries before radial artery cannulation; indirectly reflects digital perfusion.

Imaging

• Doppler ultrasound: Used to assess digital artery flow and detect occlusion or spasm.
• CT angiography: Can provide high-resolution images of hand vasculature in trauma or vascular disease workup.
• Fluorescein angiography: Sometimes used in microvascular surgery to confirm perfusion in replanted digits.

Surgical Relevance

• Digital replantation: Success depends heavily on re-establishing arterial flow through proper digital arteries.
• Flap surgeries: Local flaps based on digital artery perforators are used in reconstructive hand surgery.
• Digital sympathectomy: Performed in severe Raynaud’s disease to relieve vasospasm by interrupting sympathetic nerves around digital arteries.

Anatomical Variations

• The branching pattern of the superficial palmar arch can vary, affecting the number and size of common digital arteries.
• Some individuals have incomplete palmar arches, with greater reliance on radial or ulnar arteries for digital supply.
• Anomalous digital branches may arise directly from the radial artery or from an enlarged princeps pollicis artery.