Dermal Arteries of the Human Thumb: Arterial Units, Sucquet-Hoyer Canals, and Arterio-Arterial Anastomoses in Pad Versus Tip.

The dermal arteries of the finger are organized in discrete units. We hypothesized that the anatomy of the dermal arterial units and the number and complexity of dermal Sucquet-Hoyer canals (SHCs) differ between the tip and center of the pad of the thumb. To test this, digital HREM volume datasets (voxel dimensions of 1-3 μm³) were created from biopsies harvested from the thumb tip and pad of six body donors. They were analyzed using virtual sectioning and three-dimensional (3D) surface and volume models. In the tip samples, two to six arteries entered the dermis via a square of 4 mm2 of the dermo-hypodermal junction. They supplied 1.16 mm2 surface and connected to ∼5.5 SHCs. Conversely, in 50% of pad samples, no dermal artery entered via the dermo-hypodermal junction. In the remaining 50%, one or two arteries supplied an average surface of 2.08 mm2 and fed ∼2.5 SHCs. SHC tortuosity and the number of arterio-arterial bridge anastomoses were similar in the tip and pad. Our results support the concept of discrete dermal arterial units. The differences in the dermal microanatomy between the thumb's tip and pad are of particular significance, since they may reflect distinct functional requirements and different reactions to injury and pathogens.