The top of the wind-pipe is called the la-
rynx, and consists of live elastic cartilages.
These do not merely keep the sides of the
wind-pipe apart, and the passage for the
breath free, but they perform offices impor-
tant to the economy both of body and mind ;
they are an essential part of the instrument
of voice; they at the same time guard the
lungs from injury.

 

The thyroid cartilage is the largest of the
cartilages of the larynx, it is that we feel
projecting on the fore part of the throat,
called the pomum aclami,  It is a pro.
tection to the fine apparatus behind it, and
indeed this is the reason of its name, (sciati-
form, like a shield.) Within the thyroid
stand the arytcenoid cartilages,  This
cartilage is of an irregular triangular form.
It is socketed or articulated on the cartilage
below, and is perfectly inove-able. To the
corner which projects forwards the ligament

Fig. 25.

 

(B) is fixed, and to its other sides five Little
muscles are attached; these muscles, by
moving the cartilage, draw and vary the po-
sition of the ligament. It is these cartila-
ges and this ligament, which, vibrating in
the stream of air, give the tremor, and vo-
calize the breath ; the tones so produced are
articulated in speech.

This is a subject far from being exhaust-
ed in our philosophical works, and may call
for observation. afterwards ;* but at present
we may look on these ligaments, not as the
cordcn vocales, but in another of their ofiices
-—forming the slit which opens and shuts in
breathing, for the protection of the lungs.
But here it is pertinent to remark, that in the
structure of an animal body one organ is
made subservient to several functions, with-
out interference in the performance of anv
of them. '
rynx.

observe.

The liganients being invested with the
lining coat, or rneinbrane of the wiiid-pipe,
draw it into the form of a slit like the till of
a shop counter, and this is the Chink of the
glottis (rima glottirlis.) This slit opens and
closes with every inspiration, moving as we
see the nostrils do in breathing. But the
most admirablething of all is the acute sen.

 

_*hF0r a full description of the Vocal Organs, together
wit engravin s illustrative of the same, the reader is re-

thing might be drawn into the wind-pipe

sion of air retained in the lungs more than
necessary to respiration, and which it is pos-
sible to expel by a more forcible expiration,
there is always a possibility of coughing and
expelling the ofiensive thing at any point of
time in the act of inspiration.

so beneficently,does not extend into the wind-
pipe; for we cannot more admire the per-

ADVOCATE  INTERNAL IMPROVEMENTS.

that the lightest husk, or seed, or smallest
fly, drawn in withthe breath, and touching
the margin of the chink, is caught there by
the rapid action of the muscles and conse-
quent closing of the aperture. Now, were
the provision for the protection of the lungs
to be only thus far perfect, there would be
an effectual means of preventing the intru-
sion of foreign matter into the delicate cells
of the lungs, but not for its expulsion from
the entrance which it had reached. Accord.
ingly, although the sensibility of the glottis
is put in operation with the shutting of the
chink, it also animates another class of mus.
cles, viz. all those which, seated on the
chest, compress it, and force out the air in

sibility given to this part, and to no other, so feet adaptation of this living property, than

the circumstance of its never being bestowed
in a superfluous degree, nor extended where
it is not absolutely required. Just as the
sensibility of the skin protects the parts he-
neath, so in the some manner does the sensi-
bility ol’ the top of the wind-pipe protect all
the interior of the tube, and the lungs them-
selves, without thc necessity of this proper-
ty of irritability extending through the whole
continuous siirface.

T he simple act of sneezing affords a very
curious instance of the mutual adaptation of
muscular activity and the governing sensi-
bility. The sensation which gives rise to
this convulsive act is seated in the mem-
brane of the interior of the nostrils, and we
are not surprised with the difference of sen-

coughing; and these combining in one pow-
erful and simultaneous ‘effort, whilst the
glottis is closed, overcome that constriction,
and propel the breath through the contracted
pipe with an explosive force, which brushes
off the offending body. There is one thing
more necessary to this most important though
familiar action——-the lungs are never empty
of air: in breathing we‘ do not fully expel
the air; if we did, there would be a period
of danger occurring 17 times in a minute,
for in the first pa1't of each inspiration, sonic-

whicli_ would suffocate. But by this provi-

The sensibility seated in a spotof the throat

sation from that in the throat which excites
coiighimr. But is it not a very curious thing
to find some twenty muscles thrown out of
the action excited by irritation of the nose ;
and as many excited which were not in the
class of those influenced in coughing; and
for the very obvious purpose of shutting the
passage by the mouth, or at least forcibly
driving the air through the nostrils? No
act of the will could so successfully propel
the air through the nose in such a way as
to remove the offensive and irritating parti.
cles from the membrane of the nose, and
clear those passages. -

These last examples of an appropriate
sensibility might introduce us to an acquaint.
ance with those internal sensibilities which
govern the actions of parts quite removed
from the influence of the will; but the
description of them may be deemed unne-
eessary. We shall just hint at the guard
which nature has placed on the lower ori-

Fig.

tice of the stomach, to check the passage

_This is especially true of the la-
. It is one of those uses only, and the
least 1l1’l[.)0I‘tt1I]i,'tl']i1t\Ve have at present to

which the appetites of hunger and thirst
may have given at the upper orifice (A) to
aliinents not easy of digestion. This lower
orifice (C) is encircled with a muscular
ring; the ring is in the keeping of a
watchful guard. If we are employing the
language of metaphor, it is of ancient use.
The Greeks called this orifice pylorus, which
signifies a porter,* and his otlice is this:
When the stomach has received the food, it
lies towards the left extremity, or is slightly
agitated there. , Vi-’hen the digestive process
is accomplished, the stomach urges the food
towards the lower orifice. If the matter be
bland and natural, it passes, and no seiisa-
tion is experienced. But if crude and undi-
gestcd matter be presented, opposition is of-

26.

 

fered to its passage, and a contention is be-
gun which happily terminates in the food be-
ing thrown again to the left extremity of the
stomach, to be submitted to a more perfect
operation of the digestive powers seated
there. It is duringflthis unnatural retrograde
movement of the food that men are made
sensible of having a stomach. Yet the sen-
sations, how unpleasant ‘soever, are not to
be regarded as a punishment, but rather as
a call on reason to aid the instinctive pow-
ers, and to guard against disease by prevent-
ing impure matter froni being admitted into
the portion of the intestinal canal ‘which
absorbs, and would thus carry, those impuri-
ties into the blood to engender disease-
Such are a few cxamplesof the variety
in the sensibilities of the animal frame;

"“ The upper orifice was called by them azsaphagzis. as it

ferredtotpage-. 17,vo1: of this Magazine.

were the purveyor, from two words signifyiiig to bring
food

guarding us against external influences when
they would threaten de'struction_to the frame.
iwork, and adjustingrthe operations of inter-

 

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