NOSE. 
below the free inferior border of the septum. 
The upper edge of the septum is firmly fixed to 
the base of the skull, and its posterior edge 
gradually slopes back to the upper and back 
rt of the wide cavity of the pharynx. There 
1S no appearance of a vomer; and the nose 
_ does not project upon the face. Its position is 
_ marked externally by the nostrils, which are 
elongated vertically, oval and narrow, situated 
about three-fourths of a line from the margin of 
the upper lip and at the like distance from each 
_ other. They are not at this time closed, but 
lead straight backwards into the common nasal 
and oral cavity. 
In the following periods the chief changes 
are effected by the gradual closure of the palate, 
the fixing of the lower margin of the septum, 
the developement of the vomer, and the growth 
of the anterior part of the septum and of the 
tudiments of the nasal and superior maxillary 
bones. With these changes the nose gradually 
becomes more prominent, and the nostrils, 
which at first look straightforwards, are gradually 
_ turned obliquely downwards, and at last are 
" directed as in the adult nearly straight down- 
_ wards. During the third and fourth months, 
according to Burdach, the nostrils are closed bya 
fine membrane, which in the fifth month is again 
removed. Together with the change in their 
_ direction already spoken of, the septum becomes 
"narrower and the distance between them is 
_ diminished. Changes perfecting these are con- 
_ tinued’ even long after birth in the gradual 
_ elevation and elongation of the bridge of the 
nose, and in the narrowing of its base ; and it is 
- in these changes subsequent to birth that noses, 
- which present little variety in infants, acquire the 
_ almost infinite diversities of form by which they 
characterize the faces of adults. 
_ Physiology of the nose—Most of the pur- 
_ poses to which the nose is subservient in the 
economy are described in otherarticles. [Smext, 
‘Laryyx, Mucus, Facz.] Here, however, it 
May be considered as the first portion of the 
Tespiratory passage, and as a feature character- 
fete of Be foumnan race and of its several 
varieties. 
___ Thenose is the proper channel through which 
the air is drawn into and expelled from the 
lungs. It alone is habitually used in respi- 
Tation by most animals, and though in man the 
_ Mouth is as often used in breathing as the nose, 
_ (and, indeed, oftener in our own climate, in 
~ which, from various causes, few persons have at 
all times both the nasal passages free,) yet it is 
not adapted to this office so well as to be used 
__ long without inconvenience. Most persons 
Must have suffered the discomfort of breathing 
j through the mouth during a few hours’ sleep : 
__all its lining membrane, as well as that of the 
_ fauces and of the upper part of the larynx, be- 
_ Comes dry, and an excretion of saliva must be 
artificially produced before the annoyance and 
the danger of choking can be removed. No 
such inconvenience attends the breathing 
through the nose for any length of time. Its 
More extended mucous membrane supplies a 
fluid sufficient to keep its own epithelium moist, 
and to saturate with vapour the air which passes 
735 
over it, so that this air does not abstract so much 
moisture from the surface of the epiglottis and 
the glottis as the drier air which has passed 
through the mouth alone. 
Again, the nose is far better adapted than the 
mouth is for the arrest of the particles of foreign 
solid bodies which float in the air. If such 
particles have passed through the hairs which 
lie at the orifices of the nostrils, and which are 
sufficiently close-set to stop even very minute 
bodies, they are in their further course liable to 
be caught in the irregular surfaces of the walls 
of the nasal fosse and entangled in the moisture 
of their lining membrane. Hence, most per- 
sons can breathe through the nose for some time 
without inconvenience even in a cloud of dust: 
and the nasal cavities of the horse and other 
Mammalia are, in this respect, still better 
adapted for the protection of the lungs. Some 
experiments were performed in France to de- 
termine whether great injury of the respiratory 
passages of horses were produced by their ex- 
posure to the dust of roads. Horses were made 
to trot for a considerable distance in the clouds 
of dust thrown up by the wheels of carriages 
driven before them ; they were killed directly 
afterwards, and not a particle of dust appeared, 
on the closest scrutiny, to have passed beyond 
their nasal fosse. 
The nose is further adapted to be the first 
portion of the respiratory passage by the acute 
and peculiar sensibility of its mucous mem- 
brane, and by the connection of its nerves in 
the nervous centres with the nerves of all the 
set of respiratory muscles. Through the ol- 
factory nerve the nose detects the impurity of 
the air from those gases whose deleterious pro- 
perties are indicated by odour; and its acute 
common sensibility affords a warning of the 
presence of any mechanical or other common 
irritant. The act of sneezing, which in this 
last case is excited through the already-men- 
. tioned connection of these nerves, is an ex- 
ample of that class of half-involuntary acts* 
which are consequent on acute sensations; and, 
in this respect, it is widely distinguished from 
the other reflex acts with which it is commonly 
classed, but which are never, or*at least not 
necessarily, connected with sensation. Every 
one must have felt that a certain acute sensation 
is necessary in order that a sneeze should occur; 
and if the sensation does not arise to that cer- 
tain degree of acuteness, the disposition to the 
sudden forcible expiration gradually passes off, 
though the act had been desired and had 
seemed on the point of being accomplished. 
In this respect sneezing is exactly analogous to 
coughing,—an act which is never thoroughly 
effected except in consequence of a certain 
acuteness of sensation at the glottis. And the 
analogy is maintained in this also,—that the 
cause of irritation which produces sneezing 
may be seated either in the nose itself, where 
it is always felt, or in another part. In cough- 
* They may be thus called, because, though the 
sudden and simultaneous exertion cf all the mus- 
cles concerned is involuntary, and almost inimitable, 
yet the putting them in a position for that exertion 
is always voluntary. 
