. Cunningham's Text-book of anatomy. Anatomy. 102 OSTEOLOGY. roofed in by the thin tegmen tympani, which separates it from the middle cranial fossa. The obliquity of the medial end of the external acoustic meatus, together with the groove for the attachment of the tympanic membrane is well seen, and the thickness of the upper wall of that passage is also noteworthy. The floor of the meatus, formed by the tympanic plate, which separ- ates it from the mandibular fossa, is much thinner, but in the region of the root of the styloid process there is a mass- ing together of dense bone. HORIZONTAL SE
. Cunningham's Text-book of anatomy. Anatomy. 102 OSTEOLOGY. roofed in by the thin tegmen tympani, which separates it from the middle cranial fossa. The obliquity of the medial end of the external acoustic meatus, together with the groove for the attachment of the tympanic membrane is well seen, and the thickness of the upper wall of that passage is also noteworthy. The floor of the meatus, formed by the tympanic plate, which separ- ates it from the mandibular fossa, is much thinner, but in the region of the root of the styloid process there is a mass- ing together of dense bone. HORIZONTAL SECTION. Figure 181 represents a horizontal section passing through the face a little below the level of the inferior orbital margin, cutting through the root of each pterygoid process posteriorly. The nasal cavities and the maxillary sinuses are thus exposed. The nasal cavity is divided slightly below the inferior edge of the middle cocha along the line of the middle meatus. The thin partition, which here separates the nose from the maxillary sinus, is cut through, and the aperture into the sinus laid open. In front of this, the canal for the naso-lacrimal duct is cut across, and its relations to the maxillary sinus in front and to the lateral side, and Inferior opening of carotid to the nose medially, are well displayed. The form of the maxillary sinus, as exposed, is triangular, the summit of the triangle being directed later- ally towards the root of the zygomatic process. Its anterior wall, which is here stout, is pierced obliquely by the infra-orbital canal which at this point reaches the facial surface of the maxilla at the infra-orbital foramen. Its posterior wall, thin and convex backwards, is directed towards the infra-temporal fossa laterally, and to the pterygopalatine fossa medially, where it lies in front of the pterygoid processes. The latter fossa has been cut across and is seen to correspond to the interval between the posterior and superior surface of the maxill
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
