pars flaccida of tympanic membrane pars flaccida of tympanic membrane in human anatomy, the pars flaccida of tympanic membrane or shrapnell's membrane (also known as rivinus' ligament) is the small, triangular, flaccid portion of the tympanic membrane, or eardrum. it lies above the malleolar folds attached directly to the petrous bone at the notch of rivinus. on the inner surface of the tympanic membrane, the chorda tympani crosses this area. pars flaccida of tympanic membraneright tympanic membrane as seen through a speculum.right tympanic membrane as seen through a speculum.detailsidentifierslatinpars flaccida membranae tympanicaeta98a15.3.01.053ta26871fma56721anatomical terminology the name shrapnell's membrane refers to henry jones shrapnell, and the name rivinus' ligament to augustus quirinus rivinus.