The Journal of laryngology and otology . of these cavities is maintained. The cavitieswhich collectively constitute the middle ear are, from within out-wards : (1) the cavity of the bony part of the Eustachian tube;(2) the cavity of the tympanum ; (3) the cavity of the mastoidantrum. These several cavities are also well seen if the unitedsquamo-zygomatic and tympanic elements are removed and theinner wall of the middle ear exposed; this is easily effected if thetemporal bone is examined before the junction of the squamo-zygomatic and petro-mastoid parts has occurred. These lastnamed elements b
The Journal of laryngology and otology . of these cavities is maintained. The cavitieswhich collectively constitute the middle ear are, from within out-wards : (1) the cavity of the bony part of the Eustachian tube;(2) the cavity of the tympanum ; (3) the cavity of the mastoidantrum. These several cavities are also well seen if the unitedsquamo-zygomatic and tympanic elements are removed and theinner wall of the middle ear exposed; this is easily effected if thetemporal bone is examined before the junction of the squamo-zygomatic and petro-mastoid parts has occurred. These lastnamed elements become joined together about the period of birthand certainly during the early part of the first year. At birth,therefore, the two parts are easily separable and the middle ear isreadily exposed. At birth the middle ear cleft is easily seen, and the separationof the two parts which bound the cleft shows the chief modifica-tions which result in the separate cavities. At birth also the middle JOURNAL OF LARYNGOLOGY, RHINOLOGY, AND Fig. 1.—Ricfht temporal bone of a child aged -i years, showing the middle earcleft ? after removal of its roof, the tegmen tympani. The cleft is seen tobe continuous, and the several cavities of the middle ear are clearly distin-guishable as modified parts of the primitive cleft.
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Keywords: ., bo, bookcentury1800, booksubjectear, booksubjectnose, bookyear1887
