Fig. 1.

Eardrum anatomy and microstructure. (a) Contour plot of cat tympanic membrane using Moiré interferometry (4) with slice lines used to divide the eardrum. (b) Each slice in a is fit in the inner section as a cone and in the outer section as a toroid. This slice is from the anterior–superior quadrant, but the fit to the contour data (red squares) is typical. (c) Approximation of the eardrum obtained after slicing and fitting with cone and toroid sections. The blue line represents the annulus of the eardrum. (d) Schematic representation of the thickness profile for each slice from the umbo to the outer edge (annulus). The thickness is taken to taper linearly toward the umbo. The vertical dimension is greatly exaggerated to illustrate the four-layer composite of the eardrum. The inner radial and circumferential collagen fiber layers provide the scaffolding for the tympanic membrane (8, 11).