The nose is composed partly of bone and partly of cartilage, the
cartilages being firmly attached to the bones and to one another by
fibrous tissue.
The bridge consists of the two nasal bones which are projections of the
frontal bone of the forehead. From these are continued the nasal
cartilages which form one-half to two-thirds of the external nose.
The interior is a large and complicated chamber divided into the right
and left nares, or nostrils, by the partition called the _septum_. This,
like the external part, consists of cartilage in front, attached to bone
at the back.
=The Nostrils=, opening on the face in front, run backward for about two
inches and open into the pharynx behind. But the single canal is divided
into three separate passages some distance inward. This division is
effected by the turbinated bones which jut out into the nostril and thus
form the upper, middle, and lower air-channels. In this way the warm
surface with which cold inhaled air comes in contact is greatly
enlarged.
From the mouth cavity the nose is separated by the hard palate. On the
external nose, scattered near the tip, are numerous hairs, sebaceous
glands, and sweat glands. These glands are very liable to get blocked,
giving rise to inflamed spots, and when hairs are pulled out small
abscesses are apt to form.
=Membrane.=--The whole of the interior surface is lined with mucous
membrane, and as this has a large area, and is very well supplied with
blood, it raises the temperature of inspired air. The mucous membrane of
the nose is continuous with that of the pharynx. Any inflammation, such
as that which constitutes a “cold in the head,” is therefore extremely
liable to extend backward and finally reach the bronchial tubes and
lungs.
Over this membrane spread a multitude of small threads or nerves
resembling the twigs of a branch; there are many such branches within
the nostril, and they join together so as to form larger branches, which
may be compared to the boughs of a tree. These finally terminate in a
number of stems, or trunks, several for each nostril, which pass upward
through apertures provided for them in the roof of the arched cavity,
and terminate in the brain.
We have thus, as it were, a leafless nerve-tree whose roots are in the
brain, and whose boughs, branches, and twigs spread over the lining
membrane of the nostril. This nerve is termed the _Olfactory_.
When we wish to smell anything--for example, a flower--we close our lips
and draw in our breath, and the air which is thus made to enter the nose
carries with it the odorous matter, and brings it in contact with the
ramifications of the nerve of smell. Every inspiration of air, whether
the mouth is closed or not, causes any odorous substance present in that
air to touch the expanded filaments of the nerve.
In virtue of this contact or touching of the nerve and the volatile
scent, the mind becomes conscious of odor, though how it does so we know
as little as how the mind sees or hears; we are quite certain, however,
that if the olfactory nerve be destroyed, the sense of smell is lost.
Besides its endowment by the olfactory nerve, or nerve proper of smell,
the nostril, especially at its lower part, is covered by branches of
another nerve (known to anatomists as the fifth), of the same nature as
those which are found endowing every part of the body with the
susceptibility of heat, cold, smoothness, roughness, pleasure, and pain.
It is on this nerve that pungent vapors, such as those of
smelling-salts, strong vinegar, mustard, and the like, make the sharp
impression with which all are familiar.
=Can the Sense of Smell be Educated?=--The extent to which the sense of
smell may be educated far exceeds what most imagine can be realized from
this sense. There are probably as many odors as there are colors or
sounds; and the compass of one nostril in reference to the first, likely
differs as widely from that of another, as the compass of the eye or the
ear does in reference to the last two. The wine merchant, the distiller
of perfumes, the manufacturer of drugs, the grower of scented plants,
the epicure in things savory, the tobacco dealer, and many others, have
by long training educated themselves to distinguish differences of odor
which escape an uneducated and unpracticed nostril, however acute by
natural endowment.
=Perfumes.=--Much importance attaches to the use of perfumes by both
ancient and modern civilized nations. But all the ancient nations who
had attained to civilization, were addicted to the use of perfumes to an
extent to which no modern people at the present day affords any
parallel. Not merely as contributing to the luxury of the body were
perfumes so prized. They were used at every sacred ceremonial; lavishly
expended at the public religious services; and largely employed at the
solemn rites which were celebrated at the burial of the dead.