724 ; 
nearly equal portions, but of which the lower 
part alone reaches to the anterior aperture. 
The posterior aperture of the nasal cavities 
is quadrilateral. It is bounded below by the 
palatine plates of the palate bones, with the 
posterior nasal spine formed at their junction ; 
on each side by the internal pterygoid plate of 
the sphenoid Sow and above by the ale of 
the vomer and the body of the sphenoid bone. 
The posterior edge of the vomer divides it into 
two equal lateral parts. 
The space of which these are the apertures 
is altogether irregular in its form, but each of 
the halves into which it is divided by the sep- 
tum may be described as having four walls or 
boundaries, a superior, inferior, and two late- 
ral. The superior wall or vault of each cavity 
of the nose is formed io front by the posterior 
surface of the nasal bone; above and in the 
middle by the inferior surfaces of the nasal 
spine of the frontal, and of the cribriform plate 
of the ethmoid bone; behind by the anterior 
and inferior surfaces of the body of the sphe- 
noid bone, and its turbinated bone, and by the 
ala of the vomer. The anterior part of this 
wall looks downwards and backwards, and 
shea shallow branched grooves in which 
ranches of the internal nasal nerve lie, and 
one or more apertures through which one of 
those branches and an artery or two pass. The 
middle part of the wall is nearly horizontal, 
and is perforated by many apertures for the 
branches of the olfactory nerve, and for the in- 
ternal nasal nerve; the posterior part looks 
downwards and forwards, and presents an 
aperture leading into the sphenoidal sinuses. 
The lower wall or floor of the nasal cavity 
is nearly horizontal ; it is concave transversely, 
a little raised at each end, and narrower before 
Fig. 399. 
View of the outer wall of the nasal cavity on the right 
side. 
1, nasal bone; 2, frontal bone ; 3, frontal sinus; 
4, sphenvidal sinus ; 5, palatine surface of the hard 
palate; 6, edge of the palate bone ; 7, anterior edge 
of the superior maxillary bone. 
NOSE. 
than behind. It is formed by the u ia 
faces of the palatine plates of the sopertor ia 
illary and palate bones, and its inner border is — 
a little prolonged both behind and before upon 
their nasal spines. Near its anterior border it 
is perforated by the superior orifice of the 
anterior palatine canal. J 
The outer wall is the most complicated. 
( Fig.399.) Ifa vertical line be drawn down- 
wards from the base of the nasal spine of the 
frontal bone (a), it will have in front of it the 
plain part of this wall, a slighty concave tr 
angular surface, formed by the ascending pro 
cess of the superior maxillary bone (6), an 
resenting nothing but some shallow groovi 
or bloodvessels and nerves. And, if a similar 
line be drawn downwards from the front of th 
body of the sphenoid bone (c), it will ha 
behind it another plane surface formed by tl 
internal pterygoid plate (d). Between t 
vertical lines there is a large quadrilateral su 
face divided into three parts by the three tur 
binated bones, whose edges project in neat 
parallel and horizontal lines, at about eq 
distances one above the other. At the upp 
part of this surface and anteriorly is a th 
quadrilateral plate (e) belonging to the cell 
ap of the ethmoid bone, made very re 
y grooves and apertures which lodge bran 
of the olfactory nerve. The anterior 5 
this plate forms the inner wall of iy 
ethmoidal cells; the terior ay 
little curved outienidiat and sated as 
between its surface and the body of the sj 
noid bone into which the sphenoidal 
opens. The lower border of this plate is 
tinuous anteriorly with the inner surface 0 
middle turbinated bone, and posteriorly 
free margin which is slightly curled outs 
From the form of this margin the plate is ¢ 
the superior turbinated bone, (cornet 
rieur ; oberste Muschel;) and the space 
it here covers, and which is a kind of hor 
tal channel between its outer surface an 
wall of the adjacent ethmoidal ce’ 
superior meatus of the nose. Into thi 
the posterior ethmoidal cells open, usi 
two or more orifices concealed by the tur! 
bone; behind and a little below it” 
spheno-palatine foramen (A), at which th 
branches from the spheno-palatine ge 
and the spheno-palatine vessels enter th 
and yet further backward, and nearly 
the end of the superior turbinated bom 
opening into the sphenoidal sinuses. 
Below this upper plate, and continu 
it anteriorly, is the inner surface of the 
turbinated bone (g), another portion of 
moid bone, (cornet moyen; mitt Mr 
It is larger than thé superior, more con 
its inner surface, and presents a f 
through the whole extent of its lowe 
which is thick, and abruptly curled 0 
and sometimes has cavities within it” 
of Santorini), communicating with the 
moidal cells. The inner s he bi 
deeply grooved and perforated by blood 
and branches of the olfact n 
tine nerves. Of the grooves, whi 
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