Gerling Gregory J, Thomas Geb W
Department of Systems and Information Engineering, University of Virginia, Charlottesville, VA 22904, USA.
Somatosens Mot Res. 2008 Mar;25(1):61-76. doi: 10.1080/08990220701838996.
Understanding how skin microstructure affects slowly adapting type I (SA-I) mechanoreceptors in encoding edge discontinuities is fundamental to understanding our sense of touch. Skin microstructure, in particular papillary ridges, has been thought to contribute to edge and gap sensation. Cauna's 1954 model of touch sensibility describes a functional relationship between papillary ridges and edge sensation. His lever arm model proposes that the papillary ridge (exterior fingerprint line) and underlying intermediate ridge operate as a single unit, with the intermediate ridge acting as a lever which magnifies indentation imposed at the papillary ridge. This paper contests the validity of the lever arm model. While correctly representing the anatomy, this mechanism inaccurately characterizes the function of the papillary ridges. Finite element analysis and assessment of the critical anatomy indicate that papillary ridges have little direct effect on how SA-I receptors respond to the indentation of static edges. Our analysis supports a revised (stiff shell-elastic bending support) interpretation where the epidermis is split into two major layers with a stiff, deformable shell over an elastic bending support. Recent physiological, electrophysiological, and psychophysical findings support our conclusion that the function of the intermediate ridge is distinct from the function of the papillary ridge.
了解皮肤微观结构如何影响慢适应I型（SA-I）机械感受器对边缘不连续的编码，对于理解我们的触觉至关重要。皮肤微观结构，特别是乳头嵴，一直被认为有助于边缘和间隙感知。考纳1954年的触觉敏感性模型描述了乳头嵴与边缘感觉之间的功能关系。他的杠杆臂模型提出，乳头嵴（外部指纹线）和下方的中间嵴作为一个单一单元起作用，中间嵴充当杠杆，放大施加在乳头嵴上的压痕。本文对杠杆臂模型的有效性提出质疑。虽然该模型正确地呈现了解剖结构，但这种机制对乳头嵴功能的描述并不准确。有限元分析和关键解剖结构评估表明，乳头嵴对SA-I受体如何响应静态边缘的压痕几乎没有直接影响。我们的分析支持一种修订后的（硬壳-弹性弯曲支撑）解释，即表皮分为两个主要层，在弹性弯曲支撑上有一个坚硬、可变形的壳。最近的生理学、电生理学和心理物理学研究结果支持我们的结论，即中间嵴的功能与乳头嵴的功能不同。
