A text-book on diseases of the ear, nose and throat . in partition of bonefrom the sigmoid groove, or fossa, in which runs the lateral sinus of thedura mater, and beyond which lies the posterior cranial fossa. Inspec-tion of the base of the temporal bone (Fig. 13) shows that the medial ANATOMY AND PHYSIOLOGY OF EXTERNAL AUDITORY CANAL. 13 wall of the mastoid process forms part of the digastric groove or fossa;the canal for Arnolds nerve lies in the jugular fossa; the canal forJacobsons nerve lies between the jugular and the carotid; and thebony portion for the Eustachian tube and the semi-cana
A text-book on diseases of the ear, nose and throat . in partition of bonefrom the sigmoid groove, or fossa, in which runs the lateral sinus of thedura mater, and beyond which lies the posterior cranial fossa. Inspec-tion of the base of the temporal bone (Fig. 13) shows that the medial ANATOMY AND PHYSIOLOGY OF EXTERNAL AUDITORY CANAL. 13 wall of the mastoid process forms part of the digastric groove or fossa;the canal for Arnolds nerve lies in the jugular fossa; the canal forJacobsons nerve lies between the jugular and the carotid; and thebony portion for the Eustachian tube and the semi-canal for the tensortympani muscle have their inner wall in common with the outer wall ofthe carotid canal, on the inner end of the petrous portion or pyramid ofthe temporal bone. It must also be borne in mind that the entire in-ternal ear or labyrinth lies in the petrous part of this important bone(Fig. 12, k). The Auditory Canal.—The completely developed external auditorycanal extends from the bottom of the concha to the drum-head, and con- FiG. Vertical section of the external auditory canal, membrana tympani, and tympanic cavity, viewedfrom in front. (Politzer.) a, upper osseous ?wall of the canal; n, lower osseous wall of the same; b,tegmen tympani; c, osseous floor of the tympanic cavity ; d, tympanic cavity; e, membrana tympani;/, head of the malleus ; g, lower end of the handle of the malleus ; o, short process of the malleus ; h,body of the incus; i, stapes in the oval window; k, Fallopian canal; I, jugular fossa; ??i, glandularorifices in the skin of the cartilaginous canal. sists of a cartilaginous and bony portion, the former being about one-third, and the latter about two-thirds, of the passage-way. The lengthof this canal is about one inch and a quarter, and its average width abouta quarter of an inch. The canal gradually narrows to the middle of thebony portion (Fig. 14, a-n), where it widens again gradually to the mem-brana tympani. The external auditory cana
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Keywords: ., bookcentury1900, bookdecade1900, bookidtextbookondi, bookyear1901
