Which is the most dominant artery among ulnar dorsal, ulnar volar, radial dorsal, and radial ulnar?

Radial Artery Dominance in Digital Blood Supply

The radial artery is the dominant arterial supply to the digits in the majority of patients, particularly for the thumb (87% radial dominant) and index finger (70.5% radial dominant), with dominance decreasing progressively toward the ulnar digits. 1

Anatomical Distribution by Digit

Thumb

• 87% of thumbs demonstrate radial artery dominance, making it by far the most radially-supplied digit 1
• The princeps pollicis artery (typically arising from the radial artery system) provides the primary blood supply in 73.3% of cases 2
• The dorsal ulnar artery of the thumb is present in 100% of hands but serves a secondary role 2

Index Through Small Fingers

• Index finger: 70.5% radial dominant 1
• Long finger: 60% radial dominant 1
• Ring finger: 52% radial dominant 1
• Small finger: 52% radial dominant 1

The progressive decrease in radial dominance from radial to ulnar digits reflects the anatomical transition from radial to ulnar arterial territory across the hand 1.

Overall Hand Dominance Patterns

• Complete radial artery dominance (all digits): 28% of hands 1
• Complete ulnar artery dominance (all digits): Only 5% of hands 1
• Radial dominance in ≥3 digits: 57% versus ulnar dominance in ≥3 digits: 21.5% 1
• Equal dominance: 21.5% of hands 1

Vessel Size Comparison

The radial artery is anatomically larger than the ulnar artery at the wrist level:

• Radial artery diameter is 28% larger in the right arm (p < 0.001) 3
• 26% larger in the left arm (p < 0.001) 3
• Radial artery is the dominant vessel in 83% of right arms and 71% of left arms 3

This contradicts traditional teaching that the ulnar artery is larger, which has important implications for bypass grafting and vascular access 3.

Clinical Implications

Robust Collateral Circulation

Despite radial dominance, the hand possesses extraordinarily robust collateral circulation between radial and ulnar systems, making ischemic complications from single-vessel occlusion extremely rare 4. The American College of Cardiology notes that interventional cardiologists no longer routinely confirm collateral circulation with Allen or Barbeau tests before radial artery access, as these tests do not predict hand ischemia 4.

Radial Artery Access Safety

Even with radial artery occlusion rates of 0.8-3.0% following transradial procedures, hand ischemia remains extraordinarily rare due to ulnar artery collateralization 4. The multiple anastomotic arcades between arterial systems allow the thumb and digits to survive even after severe lesions of nearly all arteries 2.

Critical Pitfall

In rare anatomical variants where the entire arterial supply to the thumb is provided solely by the ulnar artery via the superficial palmar arch (with no radial contribution), traumatic injury to the ulnar artery could create a potential hazard 5. However, this variant is exceedingly uncommon 5.