If sufficient illumination is used, discrete thickened patches of keratin can be seen on the lateral surface of the tympanic membrane. These thickened areas which consist of numerous keratinocytes are separated by valleys lined by only one to three layers of keratinocytes. Keratin patches consistently appear as linear and discontinuous white streaks arranged along geodesic lines. There is a small area we have termed the "slow zone", located anterior and inferior to the umbo, that has comparatively fewer patches and where ink dots can remain static for several weeks. This paper describes the histology and distribution of keratin patches and postulates a mechanism for their formation, based upon the movement of the superficial layer of corneocytes towards the annulus.