A text-book of the diseases of the ear and adjacent organs . i.—The sizeof the membrana tympani presents more or lessnoteworthy deviations in different numerous measurements taken by me, itappears that the greatest longitudinal diameterfrom the point of the spina tympanica post, tothe lowes. point of the inferior margin of themembrane amounts to 9|-10 mm., the greatesttransverse diameter from the anterior to the posterior margin measures8i-9 mm. Bezolds measurements, made on specimens prepared by the average of the two diameters as 9*2 and 8*5 mm.; the thickness
A text-book of the diseases of the ear and adjacent organs . i.—The sizeof the membrana tympani presents more or lessnoteworthy deviations in different numerous measurements taken by me, itappears that the greatest longitudinal diameterfrom the point of the spina tympanica post, tothe lowes. point of the inferior margin of themembrane amounts to 9|-10 mm., the greatesttransverse diameter from the anterior to the posterior margin measures8i-9 mm. Bezolds measurements, made on specimens prepared by the average of the two diameters as 9*2 and 8*5 mm.; the thickness ofthe membrane between the handle and the tendinous ring, according to Henle,amounts to O10 mm. The Inclination of the Membrana Tympani.—The inclination of themembrana tympani depends in the adult on the inclination of the sulcustympanicus to the axis of the meatus. The inclination of the plane of thesulcus will of course be greater the farther the anterior and inferior walls ofthe meatus reach inwards beyond the posterior and superior walls (Figs, if. Tig. 15.—Sulcus ok theMembrana Tympani atthe Inner Extremity orthe Meatus. «, Sulcus ; b, Anterior su-perior grooveless bulgingout of the periphery of themembrana tympani (margotympanicus) or Riviniansegment ; c, Osseous wallof the tympanic cavity be-hind the membrana tym-pani : d. Exterior wall ofthe cavity extending intothe Eustachian tube. (Rightear.) ( URVATUKE OF THE MEMBKANA TYMPANI. 15 and 10), Be/olds measurement on corrosion preparations gives the averageangle as 27-35°. Y. Troltsch places the angle which the plane of the nieni-brane forms with the superior wall of the meatus at an average of 140°. Dr. J. Pollak maintains that there is no perceptible difference between theinclination of the membrane in the new-born infant and in the adult. Curvature of the Membrana Tympani.—In the above-described obliqueposition the membrana tympani is not stretched out as a plane surface, but iscurved in such a manner that i
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecteardiseases, bookyear
