abnormal tectorial membrane morphology abnormal tectorial membrane striated-sheet matrix morphology any structural anomaly of the laminated, striated-sheet matrix within which collagen fibrils of the TM are imbedded; the striated sheet matrix is formed by two types of fine-diameter collagen filaments, a light and a dark staining type that lie in parallel within the plane of each sheet and are extensively linked along their length by staggered cross bridges; it originates medially within the sulcal zone, extends to the marginal band and is particularly evident in apical regions of the cochlea, where it has a less compressed appearance MP:0014091