A manual of otology for students and practitioners . OVALWINDOW ROUNDWINDOW Fig. 13.—Key-plate to Fig. 12. The relative position of the canals is that the planein which each lies is practically perpendicular to theplane of the other two (Fig. 14). The axis of the tem-poral bone forms with the median line (approximately)an angle of 45 degrees, and the axes of the two bonesmake with each other an angle of about 90 degrees, ora right angle. As the superior canal is transverse to theaxis of the bone and vertical, it follows that it must be INNER EAR 37 in a plane which is parallel to that of the p
A manual of otology for students and practitioners . OVALWINDOW ROUNDWINDOW Fig. 13.—Key-plate to Fig. 12. The relative position of the canals is that the planein which each lies is practically perpendicular to theplane of the other two (Fig. 14). The axis of the tem-poral bone forms with the median line (approximately)an angle of 45 degrees, and the axes of the two bonesmake with each other an angle of about 90 degrees, ora right angle. As the superior canal is transverse to theaxis of the bone and vertical, it follows that it must be INNER EAR 37 in a plane which is parallel to that of the posterior canalon the opposite side, since this canal is vertical and itsplane is in the axis of the opposite bone. The horizontalcanals on the two sides are in the same Fig. 14.—Plane of canals and axis of temporal bone. Vestibule.—The vestibule is a small cavity which liesbeneath the bone which exists between the two ends ofthe horizontal semicircular canal. It varies in size indifferent bones but the following measurements arecorrect for an average-sized cavity: ^ inch from above,downward; | inch without, inward (Gray). It pre-sents the five openings for the three semicircular canals 38 ANATOMY AND PHYSIOLOGY OF THE EAR —above and anteriorly, the ampullated ends of the supe-rior and the horizontal canals; above and posteriorly, thesmooth end of the horizontal canal and the crus commune;below and posteriorly, the ampullated extremity of theposterior canal. Besides these five openings are theforamina for the vestibular nerve situated on the innerwall of the vestibule. On its posterior wall is the openingof the aqueductus vestibuli, which is a small canal open-ing on the posterior surface of the petrous portion betweenthe internal auditory meatu
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectear, bookyear1916
