Operative surgery, for students and practitioners . n at right angles to the former and upon alevel with the umbo, serve to divide the drum into four of the drum is performed in the lower, posterior quadrant. The Middle Ear consists of the tympanum and adjoining air-cells and the Eustachian tube. The tympanum is a wedge-shaped cavity separated from the ex-ternal auditory canal by the drum and communicating by an openingin its anterior end, through the Eustachian tube, with the the anterior part is also seen the Glaserian fissure, through whichthe middle ear co
Operative surgery, for students and practitioners . n at right angles to the former and upon alevel with the umbo, serve to divide the drum into four of the drum is performed in the lower, posterior quadrant. The Middle Ear consists of the tympanum and adjoining air-cells and the Eustachian tube. The tympanum is a wedge-shaped cavity separated from the ex-ternal auditory canal by the drum and communicating by an openingin its anterior end, through the Eustachian tube, with the the anterior part is also seen the Glaserian fissure, through whichthe middle ear communicates with the glenoid cavity and throughwhich the chorda tympani leaves the t^^mpanum. The upper partof the tympanum, the portion above the level of the membranatympani, is called the attic. In this space the ossicles are lodged. The carotid artery, surrounded by a venous plexus, traverses acanal, in the temporal bone, which is located just in front of thetympanum and which is separated from this cavity by a very thin AXATOMY OF THE EAR. 119. C-^^^W^^ ^ 120 HEAD AND FACE. plate of bone that is, at times, perforated. Behind, the tympanumcommimicates with the mastoid antrum through a short passage inthe upper part of its posterior wall, called the iter or aditus ad roof of the aditus is formed by the same thin plate of bone, tegment}Tiipani, that forms the roof of the tympanum and the antrum. Theaditus is partly occuj)ied by the body of the incus and the head of themalleus. The inner wall of the aditus presents an eminence of bonecorresponding to the external semicircular canal. Just below and infront of this there is a second, smooth, cur^^ed, linear elevation of bonecorresponding to that part of the aqugeductus Fallopii, which archesbackward and downward over the foramen ovale. The wall of the aque-duct may be thin or absent, and the facial nerve which is containedwithin it may thus readily become affected in inflammation of the mid-dle ear. The aditus will per
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Keywords: ., bookauthormcgrathj, bookcentury1900, bookdecade1910, bookyear1913
