ee ae a re ts OY 
7 
NASAL FOSS. 679 
middle turbinated bone a rounded elevation, the bulla ethmoidalis, is seen. This 
varies in size and is directed downwards and forwards, whilst opening either on it 
or above it are the orifices of the middle ethmoidal cells. Curving upwards and 
forwards, below and in front of the bulla ; 
ethmoidalis, is a deep, narrow groove, the 
hiatus semilunaris, into which the anterior 
ethmoidal cells and the antrum of Highmore 
open. The opening of the latter is placed 
near the roof of the antrum, and may be 
duplicated. The middle meatus extends up- 
wards and forwards, and, becoming narrowed, 
is continued into the infundibulum or channel 
leading into the frontal air-sinus. The 
inferior meatus (meatus nasi inferior) lies 
below the inferior turbinated bone, under | 
cover of the anterior part of which is found “eutilaves 
the slit-like orifice of the nasal duct (see 5 : 
p. 698). Ria, Siar eay § THROUGH ose OF HOES 
showing position of Jacobson’s organ. 
Mucous Membrane (membrana mucosa 
nasi).—The Schneiderian or nasal mucous membrane is thick, highly vascular, 
and firmly bound to the subjacent periosteum and perichondrium. It is continuous, 
through the choane, with the mucous lining of the naso-pharynx ; through the 
Organs of Jacobson 
Opening of middle ethmoidal cells 
Openings of posterior ethmoidal cells 
Frontal air-sinus. 
Bristle passed 
from it into 
infundibulum 
Recessus spheno-ethmoidalis 
Sphenoidal air-sinus 
\ 
FAL > 
NEES, 
Cut edge of inferior turbinated bone 
‘ Bristle passed into opening of nasal duct 
Fic. 490.—View OF THE,OUTER WALL OF THE NOSE—THE TURBINATED BONES HAVING BEEN REMOVED. 
1. Vestibule. 4, Bulla ethmoidalis. 7. Cut edge of superior turbinated bone. 
2. Hiatus semilunaris. 5. Agger nasi. 8. Cut edge of middle turbinated bone. 
3. Opening of antrum of Highinore. 6. Opening of anterior ethmoidal cells. 9. Pharyngeal orifice of Eustachian tube. 
nasal duct, with the conjunctiva; and, through the apertures leading into the air- 
sinuses, with the delicate lining of these cavities. 
Throughout the respiratory region it is covered by columnar, ciliated epl- 
thelium, interspersed amongst which are goblet or mucin cells, whilst between the 
bases of the columnar cells smaller pyramidal cells are interpolated. It contains a 
