Tensile strength of cranial pia mater: preliminary results.

OBJECT: The goal of this study was to determine the tensile strength of cranial pia mater.
METHODS: Samples of isolated bovine cranial pia mater were subjected to quasistatic traction to evaluate its tensile strength. The experimental curves of physiological deformation that were obtained can be subdivided into three parts that represent different mechanical properties: the nonlinear initial part of the curve demonstrates increasing stiffness, followed by a quasilinear pattern of elastic behavior, and finally a negative relationship (slope) between force and elongation, which characterizes a progressive deterioration. These three steps precede final sample rupture. The stiffness of the pia mater was calculated for both the initial and the linear (elastic) parts of the mean curve. The initial part and the elastic part of the curve show a typical stiffness value of 0.024 N/mm and 0.19 N/mm, respectively. The maximal mean force and corresponding maximal deformation that were attained were 1.1 N and 0.19, respectively.
CONCLUSIONS: Although very thin and apparently fragile, pia mater exhibits an unexpectedly high level of stiffness and should have a significant influence on total brain mechanical properties in response to loading.