Cone of light Cone of light The cone of light, or light reflex, is a visible phenomenon which occurs upon examination of the tympanic membrane with an otoscope. Shining light on the tympanic membrane causes a cone-shaped reflection of light to appear in the anterior inferior quadrant. This corresponds to the 4 o'clock to 5 o'clock position in the right eardrum and the 7 o'clock to 8 o'clock position in the left eardrum. The apex of the cone is at the most depressed part of the tympanic membrane, known as the umbo. The absence of a cone of light does not necessarily signify
Tympanic part of the temporal bone "foramen of Huschke" that opens onto the temporomandibular joint due to incomplete fusion of the anterior and posterior prominences during development. The bony portion of the ear canal is nearly 2 cm long and is directed inward and slightly forward: at the same time it forms a slight curve, so that the floor of the canal is convex upward. In sagittal section it presents an oval or elliptical shape with the long axis directed downward and slightly backward. Its anterior wall and floor and the lower part of its posterior wall are formed by the tympanic part; the roof and