THE NASAL SEPTUM. 169 
between which anteriorly there is an angular recess into which the cartilaginous 
septum fits. Superiorly and anteriorly the osseous septum is completed by the 
articulation of the perpen- 
dicular plate of the ethmoid 
with the nasal process of 
the frontal, together with 
the nasal crest formed by 
the union of the nasal bones; — perpendicular 
whilst posteriorly and supert- plies 
orly the perpendicular plate Nasal spine 
of the ethmoid articulates of fontal 
with the mesial ethmoidal 
erest of the sphenoid. In 
most instances the osseous 
septum is not perfectly 
vertical, but is deflected 
towards one or other side. Anterior 
Air-sinuses in connex- 2 
ion with the Nasal Fosse. | 
—Connected with the nasal | 
fossee are a number of air- 
sinuses. These are found 
within the body of the 
sphenoid, the lateral mass 
of the ethmoid, the orbital | | i 
process of the palate bone, amen ee 
the body of the superior 
maxilla, and the superciliary 
arch of the frontal bone. 
The sphenoidal sinus, of variable size, occupies the interior of the body of the 
sphenoid. In some cases it extends towards the roots of the pterygoid processes. 
In front it is formed in part by the absorption of the sphenoidal spongy bones, and 
is divided up into two cavities by a sagittally-placed partition, which, however, is 
frequently displaced to one or other side. It opens anteriorly into the roof of the 
nose in the region of the spheno-ethmoidal recess. 
The ethmoidal sinuses are placed between the lateral aspects of the upper part 
of the nasal fossee, and the cavities of the orbit, from which they are separated by 
thin and papery walls. These air spaces are completed by the articulation of the 
ethmoid with the superior maxilla, lachrymal, frontal sphenoid, and palate bones, 
and are divided into three groups—an anterior, middle, and posterior. The latter 
communicates with the superior meatus; the anterior and middle open either inde- 
pendently or in conjunction with the infundibulum into the middle meatus. 
The sinus in the orbital process of the palate bone either communicates with 
the sphenoidal sinus, or else assists in closing in some of the posterior ethmoidal 
cells. Its communication with the nasal fossa is through one or other of these spaces. 
| The maxillary sinus or antrum of Highmore lies to the outer side of the nasal 
fossxe, occupying the body of the superior maxilla. Its walls, which are relatively 
thin, are directed upwards to the orbit, forwards to the face, backwards to the 
zygomatic and spheno-maxillary fossa, and inwards to the nose. In the latter 
situation the vertical plate of the palate bone, the uncinate process of the ethmoid, 
the maxillary process of the inferior turbinated bone, and a small part of the lach- 
rymal bone assist in the formation of the thin osseous partition which separates it 
from the nasal fossa. The floor corresponds to the alveolar border of the jaw, and 
differs from the other walls in being stout and thick ; it is, however, deeply pitted 
inferiorly by the alveoli for the teeth. The antrum opens by a narrow orifice into 
the middle meatus. 
The frontal sinuses lie, one on either side, between the inner and outer tables of 
the frontal bone over the root of the nose, and extend outwards under the super- 
ciliary arches. The partition which separates them is usually central, though it 
Frontal sinus 
a 
Crista galli of ethmoid 
Cribriform plate of ethmoid 
Sphenoidal sinus 
Pituitary fossa 
WN Dorsum sell 
of sphenoid 
Alar spine 
Vomer 
External pterygoid plate 
Hamular process 
Anterior palatine foramen 
Fic. 119.—NasaL SEPTUM AS SEEN FROM THE LEFT SIDE. 
