Objective: To find out the SPA patterns and arterial supply of thumb variations in Thai population by using epoxy resin injection technique.

Material and Method: The methods used were vascular injection by epoxy resin with blue resin color to brachial artery before dissection of 100 fresh cadaveric hands to find out the SPA pattern and the anatomical variation of the princeps pollicis artery.

Results: It was found that the SPA patterns of 100 cadaveric hands were composed of 13 patterns, which could be classified into two main types: arch type and non-arch type. Arch type was found in 67 hands (67%) and non-arch type 33 hands (33%). From 13 patterns, the most common was the ulnar + 1st dorsal interosseous pattern, which found in 27 hands (27%) and the less common, in 15 hands was ulnar pattern in both arch type and non-arch type. The princeps pollicis artery was present in all of the arch-type hands (67 hands) with its origin from the radial artery. It emerged deep in the 1st dorsal interosseous muscle in 66 hands (98.5%) and dorsally to this muscle in 1 hand (1.5%). Using epoxy resin injection before dissection was a good technique with less confusion for arteries and other tissues.

Conclusion: The authors found 13 superficial palmar arch patterns, 67 percent is arch type. The princeps pollicis artery always lies deep in the first dorsal interosseous muscle. This is essential knowledge for the hand surgeon to repair or reconstruct the injured limb.

Keywords: Superficial palmar arch (SPA), Variation, Princeps pollicis artery