What supplies the dominant flow to the thumb digital arteries?

Thumb Digital Artery Blood Supply

The thumb digital arteries receive dominant flow from the first palmar metacarpal artery (also known as the princeps pollicis artery) in approximately 66% of cases, arising from the deep palmar arch (radial artery system). 1, 2

Primary Arterial Sources and Dominance Patterns

The arterial supply to the thumb demonstrates significant anatomical variation, but clear dominance patterns emerge from systematic analysis:

Dominant Source Distribution

• The first palmar metacarpal artery (princeps pollicis) provides the dominant source in 66.2% of cases, originating from the deep palmar arch (radial artery system). 2
• The first dorsal metacarpal artery serves as the dominant source in 15.5% of cases. 2
• The superficial palmar arch (ulnar artery system) provides dominant flow in only 8.2% of cases. 2
• A dominant source can be identified in 88.2% of all anatomical variations. 2

Individual Digital Artery Patterns

The thumb typically receives blood flow through four distinct digital arteries with varying incidence:

• The ulnopalmar digital artery (UPDAT) is present in 99.63% of cases, arising from the first palmar metacarpal artery in 63.15%, the first dorsal metacarpal artery in 20.54%, and the superficial palmar arch in 25.57%. 2
• The radiopalmar digital artery (RPDAT) is present in 99.26% of cases, originating from the first palmar metacarpal artery in 78.88%, the first dorsal metacarpal artery in 2.53%, and the superficial palmar arch in 23.04%. 2
• The ulnodorsal digital artery (UDDAT) is present in 83.39% of cases, supplied by the first palmar metacarpal artery in 56.95% and the first dorsal metacarpal artery in 20.62%. 2
• The radiodorsal digital artery (RDDAT) is present in 70.38% of cases, arising from the first palmar metacarpal artery in 41.48% and the first dorsal metacarpal artery in 4.81%. 2

Clinical Implications for Vascular Compromise

Radial vs. Ulnar Dominance in Practice

Understanding that the radial artery system (via the deep palmar arch and first palmar metacarpal artery) provides dominant thumb perfusion in two-thirds of patients is critical when managing upper extremity vascular injuries or planning interventional procedures. 1, 2

• The radial artery supplies the lateral forearm, lateral wrist, dorsal hand, and proximal digit portions, with the pulse palpable on the lateral flexor surface of the wrist. 1
• The ulnar artery supplies the medial forearm, wrist, hand, and most palmar/distal dorsal finger aspects, with the pulse palpable on the medial flexor surface of the wrist. 1
• Despite radial dominance for thumb perfusion, the hand possesses extraordinarily robust collateral circulation between radial and ulnar systems, making ischemic complications from single-vessel occlusion extremely rare. 1

Management of Arterial Insufficiency

When digital arterial insufficiency occurs in the setting of dialysis access or other iatrogenic injury:

• Interventional cardiologists no longer routinely perform Allen or Barbeau tests before radial artery access, as these tests do not predict hand ischemia. 1
• Even with radial artery occlusion rates of 0.8-3.0% following transradial procedures, hand ischemia remains extraordinarily rare due to ulnar artery collateralization. 1
• For forearm arteriovenous fistula complications causing digital hypoperfusion, endovascular embolization of the distal radial artery combined with ulnar artery angioplasty can restore adequate hand perfusion by leveraging the collateral network. 1

Important Anatomical Variations and Pitfalls

Single End-Arterial Supply Risk

• In 75% of specimens, there is a single end-arterial blood supply to the thumb, making the thumb vulnerable to ischemia if this dominant vessel is injured. 3
• Anatomic variations in thumb arterial patterns are present in 25% of cases, requiring careful preoperative assessment when planning thumb reconstruction or replantation. 3

Rare Complete Ulnar Dependence

• In rare cases (approximately 8%), the entire arterial supply to the thumb may be provided solely by the superficial palmar arch (ulnar artery system) with no contribution from the radial artery. 4
• This creates a potential hazard in the event of traumatic injury to the ulnar artery, as no collateral supply exists from the radial system. 4

Multiple Anastomotic Networks

• Multiple anastomoses exist between radial and ulnar digital arteries and between dorsal and palmar systems, allowing the thumb to survive even after severe lesions of nearly all arteries. 5
• These interconnected systems provide multiple alternatives in flap design without endangering survival. 5

Practical Assessment Approach

When evaluating thumb perfusion clinically:

• Palpate both radial and ulnar pulses at the wrist on the flexor surface, with the radial pulse lateral and ulnar pulse medial. 1
• Do not deny patients radial artery procedures based on "failed" Allen tests, as hand ischemia risk remains minimal even with radial artery occlusion. 1
• When planning thumb reconstruction or managing vascular injury, recognize that the first palmar metacarpal artery (princeps pollicis) from the radial system is the dominant source in two-thirds of patients, but significant anatomical variation exists. 2, 3