ABSTRACT
The tympanic membrane is irregularly round and slightly conical in shape; the apex of the cone is located at the umbo, which marks the tip of the manubrium. In the adult, it is angulated approximately 140° with respect to the superior wall of the external auditory canal. The vertical diameter of the tympanic membrane as determined along the axis of the manubrium ranges from 8.5 to 10 mm, while the horizontal diameter varies from 8 to 9 mm (8). The malleal prominence (Fig. 1), a projection formed by the lateral process of the malleus, is located at the superior end of the manubrium. The manubrium is firmly attached to the tympanic membrane at the umbo and lateral process and is clearly visible throughout its length (the stria mallearis). The anterior and posterior tympanic striae extend from the lateral process of the malleus to the anterior and posterior tympanic spines, respectively. These striae divide the tympanic membrane into larger pars tensa below, and smaller triangular pars flaccida (or Shrapnell’s membrane) above.
