A treatise on the diseases of the ear including the anatomy and physiology of the organ together with the treatment of the affections of the nose and pharynx which conduce to aural disease . s part takesthe form of a vertical slit, the height of which increases graduallytowards the pharynx. The general direction of the Eustachian tubeis from the tympanum behind and above, forwards, downwards, andtowards the mesial line. Its axis forms an angle of 150^ withthat of the external meatus. The tube is usually said to presentan outer and inner wall, a floor and a roof. The sides, however,almost meet
A treatise on the diseases of the ear including the anatomy and physiology of the organ together with the treatment of the affections of the nose and pharynx which conduce to aural disease . s part takesthe form of a vertical slit, the height of which increases graduallytowards the pharynx. The general direction of the Eustachian tubeis from the tympanum behind and above, forwards, downwards, andtowards the mesial line. Its axis forms an angle of 150^ withthat of the external meatus. The tube is usually said to presentan outer and inner wall, a floor and a roof. The sides, however,almost meet below, and in the cartilaginous portion the upperboundary of the tube is the angle formed by the approximationof the walls. 48 THE ORGAX OF HEARIXG. The walls of the osseous portion of the tube at the tympanicend are continuous with those of the cavity, except below, wherethe orifice is marked by a sharp curve downwards to the anteriorwall of the tympanum. The roof is formed by the floor andlateral wall, partly osseous and partly fibrous, of the canal for thetensor tympani muscle. On transverse section the osseous portionis triangular in form, with the base above and the apex below ;. Eustachian Tube and Tympanic Cavitv, Right Ear. {PoUtzer.) a, membrana tj-mpani; b, head of the malleus ; c, lower end of the handle of the malleus ; d, bodyof the incus ; e, short process of the incus ; /, tensor tympani; g, ostium pharjmgeum tubse ;h, isthmus iubfe ; i, ostium tympanicum tubs. towards the tympanum the lateral walls are separated below, anda floor may be said to exist, which is sometimes divided into twoparts by a minute crest. The internal wall of the osseous tubeis constituted by the neighbouring part of the carotid canal,and close to the tympanic orifice is the opening of the minutecanal which transmits the small deep petrosal nerve. Minuteperforations sometimes exist in the septum between the osseous THE EUSTACHIAN TUBE. 49 tube and the carotid canal. At the tympanic orifice
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Keywords: ., boo, bookcentury1800, bookdecade1890, booksubjectear, bookyear1894
