A text-book of the diseases of the ear for students and practitioners . rana tympani into four segments in order to clearly under-stand its relation to the internal tympanic wall. This is accomplished byprolonging a line downwards from the handle of the malleus, and intersecting(it by a horizontal line tangent to its lower extremity. The points of projec-tion, as given by Zuckerkandl,* of the inner tympanic wall to the drummembrane applies perfectly to anatomical preparations, but is considerablymodified in practice on account of the inclination of the membrane to thehorizontal In the
A text-book of the diseases of the ear for students and practitioners . rana tympani into four segments in order to clearly under-stand its relation to the internal tympanic wall. This is accomplished byprolonging a line downwards from the handle of the malleus, and intersecting(it by a horizontal line tangent to its lower extremity. The points of projec-tion, as given by Zuckerkandl,* of the inner tympanic wall to the drummembrane applies perfectly to anatomical preparations, but is considerablymodified in practice on account of the inclination of the membrane to thehorizontal In the normal position of the head, in which otologicalexaminations are made, we find that: * Bealencyclopddie der med. Wissenschaften. Wien, 1886. ArticleGehororgan. f This difference in projection between anatomical aural preparations andthe ears of the living, is also due to the oblique position of the temporal bonewhen in situ, and also to the position in which Zuckerkandl held the specimenwhile making his projections.—Translators. THE WIDTH OF THE TYMPANIC CA VITY 5i. 1. The anterior superior quadrant of the membrana tympani (a)corresponds to the anterior superior portion of the inner tympanic wall whichborders on the tympanic orifice of the Eustachian tube; a part of the semi-canal for the tensor tympani muscle is seldom seen in this quadrant. 2. The anterior inferior quadrant (b) corresponds to the anterior inferiorpart of the inner tympanic wall which borders on the ostium tubae, and alsopresents a portion of the jagged anterior and inferior walls. 3. The posterior superior quadrant (c) corresponds to the posteriorsuperior part of the inner tympanic wall which presents the incudo-stapedialjoint above, behind this, the eminentia stapedia and the tendon of thestapedius, and below these the larger superior part of the recess or niche ofthe round window (e). 4. _ The posterior inferior quadrant (d) corresponds to the posteriorinferior part of the inner tympanic wall which presen
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