Terminal branches of radial + ulnar arteries anastomose in the palm, forming two arches that ensure uninterrupted digital blood supply during gripping.

Superficial Palmar Arch

Formation: Direct continuation of ulnar artery (main contributor) + superficial palmar branch of radial artery (completes laterally)

Level: Distal border of fully extended thumb

Relations:

• Superficial: palmaris brevis; palmar aponeurosis
• Deep: long flexor tendons (FDS, FDP); lumbricals; digital branches of median + ulnar nerves

Branches:

Superficial arch supplies medial 3½ fingers (3 common + 1 proper digital arteries)

Deep Palmar Arch

Formation: Direct continuation of radial artery (main contributor) + deep palmar branch of ulnar artery (completes at base of 5th metacarpal)

Course of radial artery to deep arch:

1. Anatomical snuffbox (deep to APL, EPB, EPL; crosses scaphoid + trapezium)
2. Proximal 1st interosseous space
3. Between two heads of 1st dorsal interosseous → enters palm
4. Deep to oblique head of adductor pollicis → through adductor pollicis heads → deep palmar arch

Level: ~1 cm proximal to superficial arch; deep to long flexor tendons

Key relation: Deep branch of ulnar nerve travels within the concavity of the arch

Branches:

Additional radial artery branches (before completing arch):

• Princeps pollicis → 2 branches for palmar surface of thumb
• Radialis indicis → lateral side of index finger

Comparison

Applied Anatomy

Laceration of Palmar Arches

• Profuse bleeding, difficult to control — arches are under arterial pressure + richly anastomotic
• Control: compression of brachial artery against humerus (most effective)
• Ligating radial or ulnar artery at wrist alone fails — both arches remain connected via carpal arch anastomoses

The arteries of the hand are the terminal branches of the radial and ulnar arteries. They anastomose in the palm to form two arterial arches — the superficial palmar arch and the deep palmar arch — which ensure an uninterrupted blood supply to the digits even when the hand is gripping.

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Superficial Palmar Arch

Formation

The superficial palmar arch is formed by the direct continuation of the ulnar artery (main contributor) beyond the flexor retinaculum, completed laterally by the superficial palmar branch of the radial artery.

The ulnar artery is the dominant contributor. The superficial palmar branch of the radial artery is small and simply completes the arch on its lateral side.

Level and Surface Anatomy

The arch lies across the palm at the level of the distal border of the fully extended thumb. Its convexity is directed towards the fingers.

Relations

Branches

The superficial palmar arch thus supplies the medial 3½ fingers (via the 3 common + 1 proper digital arteries).

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Deep Palmar Arch

Formation

The deep palmar arch is formed by the direct continuation of the radial artery (main contributor), completed medially at the base of the 5th metacarpal by the deep palmar branch of the ulnar artery.

The radial artery is the dominant contributor. It reaches the palm after traversing the anatomical snuffbox and passing between the two heads of the 1st dorsal interosseous muscle.

Course of Radial Artery to the Deep Arch

1. Winds posteriorly around the wrist → enters the anatomical snuffbox
2. Lies deep to APL, EPB, and EPL tendons in the snuffbox; crosses the scaphoid and trapezium
3. Passes distally to the proximal end of the 1st interosseous space
4. Passes between the two heads of the 1st dorsal interosseous muscle → enters the palm
5. Passes deep to the oblique head of adductor pollicis, then between the two heads of adductor pollicis → forms the deep palmar arch

Level and Surface Anatomy

The deep palmar arch lies approximately 1 cm proximal to the superficial palmar arch. It is deep to the long flexor tendons.

Relations

Branches from Deep Arch

Additional Branches of the Radial Artery in the Palm

Before completing the deep arch, the radial artery gives off two important named branches:

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Comparison — Superficial vs Deep Palmar Arch

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Applied Anatomy

Laceration of Palmar Arches

Wounds of the palmar arches cause profuse and often uncontrollable bleeding because:

• The arches are under arterial pressure
• Both arches are richly anastomotic — bleeding continues even after the wound contracts

Control of bleeding:

• Compression of the brachial artery against the humerus — most effective method
• Ligation of the radial artery or ulnar artery at the wrist alone fails to control bleeding, because the palmar arches remain connected to the palmar and dorsal carpal arches proximally

Clinical point: Surgeons must not assume that ligating one forearm artery controls palmar haemorrhage. Both vessels contribute to both arches via anastomotic channels, and the arches themselves communicate with the carpal arches.

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