<prompt> Surface area of tympanic membrane ear drum?55 mm270 mm280 mm290 mm2  <response>: Ans. D. 90 mm2. Ref: PL Dhingra 5thpg. 18. The tympanic membrane has a cross-sectional area of approximately 90 sq. mm. and the energy falling on that area is concentrated upon an area of 3.2 sq. mm. represented by the stapes. TYMPANIC MEMBRANE The normal tympanic membrane is pearlyshiny gray color. 6 It has an oval shape with an average surface area of approximately 90mm2. The concavity on its lateral surface is more marked. The normal tympanic membrane is mobile. It consists of a lax portion, the pars flaccida sharpells membrane, and a larger taut portion, the pars tensa, which is drawn inwards at its center to form the umbo. At the tip of the malleus is the umbo.6 Some middle ear structures can be seen through a transparent membrane. Most prominent part of tympanic membrane seen on Otoscopy is the lateral process of the malleus. Attic area is pinkish and lies above lateral process of the malleus TM can be divided into 4 quadrants: - anterosuperior - anteroinferior - posterosuperior - posteroinferior The quadrants of TM are clinically important as they are used in describing the location of lesions. Cone of light helpful in evaluating tension of TM is seen in the anteroinferior quadrant. The most common site of Cholesteatoma is Posterosuperior part. note: AQUINOS SIGN is the blanching of the tympanic mass with gentle pressure on the carotid artery. The surface area of tympanic membrane 90 mm2 Effective vibratory area of tympanic area 45 mm2. Foot plate area 3.2 mm2 Area ratio 14:1 Ossicular ratio6 1.3: 1 Total transformer ratio 14 x 1.3: 1-18.2: 1 