Variation in glabrous skin physiology across anatomical locations on the human hand

Skin physiology varies greatly between anatomical locations, with impact on tactile sensitivity. Research on the variations in morphology and physiology between different anatomical locations of glabrous skin is limited so far. This study investigates the morphology and physiology of glabrous skin on the human hand (N = 60), including the index finger pads of dominant and non-dominant hand, the small finger pads, the thenar palm and the volar arm as hairy skin reference. We employed laser scanning microscopy, optical coherence tomography, skin corneometry, skin cutometry and two-point discrimination measurements as non-invasive in situ methods. We found significant morphological and physiological differences between fingers, palm and volar arm. The finger pads had a thicker stratum corneum (SC), especially the index finger of the dominant hand. They also exhibited higher skin hydration and a higher density of Meissner corpuscles and of sweat glands compared to the palm. All parameters exhibited strong interindividual variability. A correlation between anatomical positions for individuals was found for some but not all parameters. The skin's mechanical response differed significantly between the anatomical locations, in correlation with skin hydration for all glabrous skin positions. The effect of ageing on skin elasticity was strongest on the hairy skin of the volar arm. In glabrous skin ageing affected the density of Meissner corpuscles and thus spatial acuity. Glabrous skin exhibits a high specialization depending on the anatomical position. Physiological and morphological parameters play a crucial role in its mechanical properties and tactile acuity. KEY POINTS: Skin physiology varies between anatomical locations, with impact on tactile sensitivity. However very little attention has been paid to the glabrous skin of our hands. We evaluate non-invasively the morphological physiological differences between the index finger pads of the dominant and non-dominant hands, the small finger pads, the palm and the volar arm as representative of hairy skin (N = 60). Skin is highly specialized depending on the anatomical position. The thickness of the stratum corneum (SC) decreases from the dominant index finger to the palm; skin hydration in the SC and density of Meissner corpuscles (MCs) are higher on the finger pads than on the palm. Skin parameters vary largely between participants but are often correlated between anatomical positions across participants. The main effect of increasing age is a decrease in the density of MCs, with the strongest negative correlation for the index finger of the dominant hand, which also exhibits the strongest decrease in tactile acuity with age.