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turbinate and the roof of the nose (see Figs. 2, 4 and 5). In front of the turbinates the outer wall of the nose is smooth: its lowest and most anterior part is lined by skin continuous with that of the face, and forms the outer wall of the vestibule. Behind and above the vestibule and on a level with the entrance to the middle meatus of the nose is a smooth triangular area of mucous membrane known as the atrium of the middle meatus (see Fig. 2). Occasionally a slight elevation is found in the atrium near the anterior end of the middle turbinate. This is

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FIG. 2.-VERTICAL ANTERO-POSTERIOR SECTION OF THE HEAD PASSING THROUGH THE RIGHT NASAL FOSSA IMMEDIATELY TO THE OUTER SIDE OF THE SEPTUM. a. Lower jaw; b. hard palate; c. inferior meatus; d. inferior turbinate; e. middle meatus; middle turbinate; g. superior turbinate; h. superior meatus; i. frontal sinus; k. posterior ethmoidal cell; fourth or highest meatus; m. sphenoidal sinus: n. body of the sphenoid; o. Eustachian tube.

known as the agger nasi, and constitutes the remains of the large nasal turbinate of the carnivora.

The inferior turbinated body is about 40 to 50 mm. long, and 12 to 15 mm. in width near the centre, its widest part. It tapers rapidly towards both extremities: the anterior end is more rounded and larger than the posterior. On transverse section near its central part the inferior turbinate is seen to be markedly curved, and to consist of a horizontal and a vertical limb (Fig. 5). In the adult the lower edge lies 3-4 mm. above the floor of the nose; in the new-born it is almost in contact (Fig. 8).

The inferior meatus of the nose is small in front, smaller still behind, and much more roomy in the centre, owing to the strong outward bend of the outer wall of the nose and the curved line of attachment of the inferior turbinate. The average length of the inferior meatus is 60-65 mm., though according to Thane, it may attain 73 mm. The width of

the inferior meatus measured from the septum to the outer wall of the nose, near its central part, is 12-18 mm.; the height is about 20 mm. At the highest part of the meatus and under the inferior turbinate, about 25 mm. behind the entrance to the nose, is the orifice of the

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FIG. 3.-VERTICAL ANTERO-POSTERIOR SECTION THROUGH THE NASAL FOSSA SOMEWHAT TO THE LEFT OF THE MIDDLE LINE. The middle turbinate has been removed and a dissection made to expose the structures on the outer wall of the nose. a. Uvula; b. soft palate; c. Eustachian tube; d. sphenoidal sinus; e. ostium of the sphenoidal sinus; posterior ethmoidal cell; g. middle ethmoidal cell; h. frontal sinus; i. infundibulum; k. a window cut in the uncinate process to show the fossa on its outer side; . uncinate process; m. hiatus semilunaris; 2. attachment of the middle turbinate; o. inferior turbinate; p. inferior meatus; q. hard palate.

nasal duct, which is often marked by a small crescentic fold of mucous membrane (Fig. 6).

The shape of the inferior meatus is of some surgical importance, for the width of the air-way may be greatly increased by simply removing the anterior extremity of the inferior turbinate and thus allowing free access

to the larger middle part of the meatus. Upon this observation is based the operation of anterior turbinectomy.

The middle turbinate varies from 30-40 mm. in length and is 15 mm. in height in its largest part. Arising from the lateral mass of the ethmoid it curves inwards, downwards, and finally outwards. Its line of attachment, as shown in Figs. 3 and 15, consists of an anterior hook-shaped part and a posterior nearly horizontal part. Under the anterior hook-shaped part, the middle meatus bulges upwards and forms a cavity known as the recessus meatus medii which approaches closely to the floor of the frontal sinus. The free border of the middle turbinate is often thickened,

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FIG. 4.-VERTICAL TRANSVERSE SECTION THROUGH THE NASAL FOSSA IN THE PLANE OF THE OPTIC NERVES AND THE THIRD MOLAR, VIEWED FROM THE FRONT. a. Optic nerve; b. superior turbinate; c. middle ethmoidal cell; d. septum; e. middle meatus; . ostium of the maxillary antrum; g middle turbinate showing a cell; h. maxillary antrum; i. inferior meatus; k. inferior turbinate.

especially at its anterior extremity, where a small air-cell may be found. Lothrop found this cell present in 18 per cent. of his specimens, but in 6 per cent. it was quite small. Harmer stated that the cell was commonly present and that it was lined with normal mucous membrane similar to that of other ethmoidal cells. In disease the cell may become greatly distended. The anterior border of the middle turbinate commonly runs vertically downwards and joins the horizontal border at a well-marked angle, thus forming the lobulus, or operculum meatus medii (see Fig. 2). Occasionally the middle turbinate is partially divided into two by a slight horizontal furrow which is most marked posteriorly.

The removal of the middle turbinate brings into view the uncinate process, the hiatus semilunaris, the bulla ethmoidalis and the openings of the infundibulum, of the maxillary antrum and of some of the anterior ethmoidal cells (Fig. 3).

The uncinate process is a narrow shelf on the outer wall of the nose, broadest in front, and gradually tapering behind. It arises in front from the anterior portion of the lateral mass of the ethmoid in close proximity to the upper part of the anterior border of the middle turbinate. It thence passes downwards and backwards parallel to the bulla ethmoidalis, ending just below and behind the maxillary ostium. It is slightly curved, with its concavity upwards. The inner convex surface looks downwards, inwards and forwards. The external concave surface looks outwards, upwards and backwards, and forms the lower border of the hiatus semilunaris (see Figs. 3 and 5).

The bulla ethmoidalis is a smooth rounded eminence lying just above the

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FIG. 5.-VERTICAL TRANSVERSE SECTION OF THE NOSE, IN THE PLANE OF THE EYEBALLS AND SECOND MOLARS, VIEWED FROM BEHIND. a. Inferior turbinate; b. middle fossa; c. uncinate process; d. nasal septum; e. superior turbinate; f. pupil; g. middle ethmoidal cell; h. middle turbinate; i. infra-orbital vessels and nerve; k. cavity of the antrum; 7. inferior meatus; m. hard palate.

uncinate process, and extending upwards to the attached border of the middle turbinate. It is formed by the projection of one or more of the larger middle ethmoidal cells, and varies greatly in size, according to the degree of development of these cells (see Fig. 3).

Between the bulla ethmoidalis and the uncinate process is a long, narrow, half-moon-shaped cleft, the hiatus semilunaris. It is 15-20 mm. long and about 3-4 mm. in width. Its anterior end, which is deepest, reaches up into the recessus meatus medii: its posterior part gradually shallows away. Into this cleft open the infundibulum in front, the ostium maxillare near its posterior end, and some of the anterior ethmoidal cells, usually near the anterior end. These openings are entirely concealed from view until the uncinate process has been removed. From this anatomical arrangement it will be seen how easily swelling of the mucous membrane,

which is very loosely attached in this region, will occlude the openings of the cavities: and further that it will be very difficult, or quite impossible in most instances, to catheterize the sinuses through the ostia in the living subject.

The superior turbinate is a small thin projection situated far back and high up in the nose. It is usually 5-6 mm. long, but may attain the

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FIG. 6.-VERTICAL SECTION OF THE NOSE BEGINNING IN THE BODY OF THE SPHENOID, NEAR THE MIDDLE LINE, AND PASSING OBLIQUELY FORWARDS THROUGH THE OUTER WALL OF THE NOSE AND THE ORBIT. Viewed from the outer side. Part of the inner wall of the orbit and of the inner wall of the antrum have been subsequently cut away to show the infundibulum, the ethmoidal cells, and the large concavities under the middle and inferior turbinates. a. Post-pharyngeal wall; b. posterior margin of the nasal septum; c. outer surface of the middle turbinate; d. sphenoidal sinus showing a probe inserted into its ostium; e. posterior ethmoidal cells; f. middle ethmoidal cells; g. inner wall of the orbit; h. position of ostium of frontal sinus surrounded by anterior ethmoidal cells; . probe passed down the infundibulum into the middle meatus; k. inner wall of the orbit; . lachrymal duct; m. ostium of maxillary antrum; n. and o. parts of inner wall of antrum; p. large external surface of inferior turbinate; 9. hard palate; r. socket of first molar tooth showing its proximity to floor of antrum.

length of 15 mm. Under normal conditions it can be seen by posterior, but not by anterior, rhinoscopy.

The superior meatus is a mere short slit into which the posterior ethmoidal cells open, generally by one or two roundish ostia.

The fourth or highest meatus, sometimes called the spheno-ethmoidal recess, is the space above and behind the superior turbinate and below

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