EEMCO guidance to the in vivo assessment of tensile functional properties of the skin. Part 1: relevance to the structures and ageing of the skin and subcutaneous tissues.

From an engineering point of view, the skin and subcutaneous tissue represent an integrated load-transmitting structure. It is subjected to intrinsic and environmental influences. An attempt to use a four-layered model is offered to explain how the integument withstands and transmits loads through deforming appropriately. The stratum corneum, the association between the living epidermis and papillary dermis, the reticular dermis and the hypodermis have each their own intimate structures whose tensile functions are ideally balanced to respond adequately to the casual mechanical demands. A series of physiological variables, ageing and skin diseases alter the tensile functions of the organ. In the overall analysis, truly comprehensive multidisciplinary approaches in this field have brought advances in the understanding of functional skin biology. The assessment of tensile functions of skin also provides incentives for progress in skin care.