ABSTRACT
Fingertip pulp is comprised of the skin and underlying fatty tissue on the ventral surface of the distal phalanx of each digit. Forces applied to the skin by contact with the environment may not be the same as the forces applied to the skeleton, because the pulp of the fingertips may affect the temporal and spatial distribution of the forces. A biomechanical model of the fingertip pulp is needed to bridge the gap between the external force applied to the skin and the forces acting on the phalanges of the digits. Serina (1996) developed a quasi-static mechanical model of fingertip pulp for use in analysing keyboarding tasks. It used an axisymmetric, ellipsoidally shaped membrane with a uniform internal pressure to model the finger pulp. The membrane was assumed to extend infinitely between two parallel, rigid plates. The subcutaneous tissue was modelled as an incompressible, inviscid fluid; the skin was modelled as an isotropic, elastic, incompressible continuum undergoing finite deformations. Model predictions were compared to in vivo measurements of pulp displacement under a variety of loading conditions. Although that model assists in understanding finger pulp mechanics quasi-statically, a fully dynamic model is necessary for use in analysing the rapid finger movements associated with keyboard use or piano playing.
