"Cone of light" is due to:
Cone of LightSeen in anteroinferior quadrant of the tympanic membrane is actually the reflection of the light projected into the ear canal to examine it.This pa reflects it because it is the only pa of tympanic membrane that is approximately at right angles to the meatus.This difference in different pas of the tympanic membrane is due to the handle of malleus which pulls the tympanic membrane and causes it to tent inside.Thus, the handle of malleus causes tenting and because of tenting the anteroinferior quardrant is at right angles to the meatus and thus reflects the light (leading to cone light).
Malleolar fold
Handle of malleus
Anterior inferior quadrant
Stapes