purge the Cell.
In its passage through the capillaries of the body the blood
gives up to the tissues the materials necessary for their growth
and nourishment, and at the same time receives from the tissues
the waste products resulting from their metabolism. Living
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 69
material is in a continual state of unstable chemical equilibrium,
building itself up on the one hand, and breaking down on the
other. The term used for the sum total of these intra-molecular
rearrangements is metabolism. The chemical substances in
the protoplasm with which the multitudinous cells of the body
are filled contain complex nitrogenous compounds called proteins.
So far as is at present known protein material is never absent
from living substance, and is never present in anything else but
that which is alive or has been formed by the agency of living
cells. It may therefore be stated that protein metabolism is the
most essential characteristic of vitality. To understand the
nature of the tissues of the various parts of the body that are
nourished by the blood we must again refer to the cellular nature
of them. In our description of the teeth cells formed during
the earlier stages of dentition, we endeavoured to show how those
parts were built from simple forms to more complex ones. The
same development applies to all tissues, whether hard or soft
muscle-tissue or bone-tissue and thenceforward in the adult,
when all development has subsided, those final cells of the body
have to be maintained by the processes of nourishment and
metabolism that are now being described.
The adult body consists of a great number of different parts,
and each part has its own special work to do. Such parts of
the body are called organs. Each organ does not only its own
special work, but acts in harmony with other organs. This
relationship between the organs enables us to group them to-
gether into what are termed systems. Thus we have the circu-
latory system, which consists of the group of organs heart,
arteries, veins, arterioles, and capillaries concerned in the
circulation of the blood; the respiratory system, which includes
the group of organs air passages, lungs, nerves, etc. concerned
in the act of breathing; the digestive system, which deals with
the digestion of food; the excretory system, which is engaged in
getting rid of waste products; the muscular system, which works
the movements of the body; the skeletal system, which supports
the soft parts of the body. Over and above all this is the nervous
system -brain, spinal cord, and nerves which constitutes the
great master system of the body, and which presides over, con-
trols, and regulates the functions of all the other systems.
If we proceed to make an anatomical analysis, and take any
organ, we see that it consists of various textures, or, as they are
70 OPERATIVE DENTAL SURGERY
called, elementary tissues. Just as one's garments are made up
of textures, cloth, lining, buttons, etc., so each organ is composed
of corresponding tissues.
The elementary tissues come under the following four headings :
1. Epithelial tissues.
2. Connective tissues.
3. Muscular tissues.
4. Nervous tissues.
Each of these is again divisible into sub-groups. If we con-
tinue our anatomical analysis still further, we shall find that
the individual tissues are built up of structures which require the
microscope for their accurate study. Just as the textures of a
garment are made up of threads of various kinds, so also in many
of the animal tissues we find threads or fibres as they are called.
But more important than the threads are little masses of living
material. Just as the wall of a house is made up of bricks united
by cement, so the body walls are built of extremely minute living
bricks, united together by different amounts of cementing
material. Each one of these living units is called a cell. Some
of the tissues already mentioned consist of cells with only very
little cement material binding them together; this, for instance,
is seen in epithelial tissues; but in other tissues, particularly the
connective tissues, which are not so eminently living as the rest,
the amount of cement or intercellular material is much greater,
and in this it is that the fibres are developed that confer the
necessary strength upon these binding tissues.
If, instead of examining the adult animal, we look at the animal
in its earliest stage of development, the ovum, we find that it
consists of a single little mass of living material, a single cell. As
development progresses it becomes an adherent mass of cells.
In the later stages of development various tissues become
differentiated from each other by the cells becoming grouped in
different ways, by alteration in the shape of the cells, by deposi-
tion of intercellular matter between the cells, and by chemical
changes in the living matter of the cells themselves. Thus, in
some situations the cells are grouped together into the various
epithelial linings ; in others the cells become elongated and form
muscular fibres ; and in others, as in the connective tissues, there
is a preponderating amount of intercellular tissue which may be
permeated with fibres, or be the seat of the deposition of calcium
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 71
and other salts, as in bone and the teeth. Instances of chemical
changes in the cells themselves are seen on the surface of the
body, where the superficial layers of the epidermis become horny ;
in the mucous glands, where they become filled with mucin ; and
in adipose tissue, where they become charged with fat.
The term " cell " was first used by botanists. In the popular
sense of the word a cell is a space surrounded by a wall, as the cell
of a prison or the cell of a honeycomb. In the vegetable cell
there is a wall, made of the starch-like material called cellulose.
Within this wall is the living matter and a number of large spaces
or vacuoles filled with a watery fluid. But the animal cell is
different. As a rule, it has no obvious wall, and vacuoles are not
conspicuous. It is just a little lump of living material. This
living material is jelly-like in consistency, possessing the power
of movement ; the name of protoplasm has been bestowed upon
it. Somewhere in the protoplasm of all cells, generally near the
middle in animal cells, is a roundish structure of more solid
consistency than the rest of the protoplasm, called the nucleus.
An animal cell, therefore, may be defined as a mass of proto-
plasm containing a nucleus (see Chapter II., p. 16).
Venous Blood and Pulmonary Circulation.
The circulation of the blood, therefore, is to nourish the tissues
of the body and carry away the waste products. In doing so it
becomes changed from arterial into venous blood, which is
collected by the veins, and through them returned to the "right
auricle of the heart. From this cavity the impure blood passes
into the right ventricle and is thence conveyed through the pul-
monary arteries into the lungs. In the capillaries of the lungs
it again becomes arterialized, and is then carried to the left
auricle by the pulmonary veins.
Arterial Blood and Systemic Circulation.
From the left auricle it passes into the left ventricle, from
which the cycle once more begins. The course of the blood from
the left ventricle through the body generally to the right side of
the heart constitutes the greater or systemic circulation, while
its passage from the right ventricle through the lungs, where the
venous blood has been oxygenated or arterialized, to the left side
of the heart, is termed the lesser or pulmonary circulation.
72 OPERATIVE DENTAL SURGERY
The heart is a hollow muscular organ, situated in the thorax
or chest, between the lungs, and enclosed within a bag called the
pericardium or pericardial sac. It rests on the diaphragm some-
what to the left of the median or centre line of the chest. It is
conical in form, and is suspended by the great vessels in such a
manner that the apex points to the left and downward. Its size
is about that of the closed fist, and its average weight is about
ten ounces. It is divided by a septum, or wall, into two cavities
not connected with each other, in each of which is contained an
auricle or blood-receiving chamber and a ventricle or blood-
distributing chamber. The capacity of the auricles is about
four ounces, and that of the ventricles about six ounces. This
organ is controlled by two sets of nerves, which are branches from
the pneumogastric or vagus nerves and the sympathetic nerves.
The vagus nerves have a slowing or inhibitory effect and the
sympathetic have an acceleratory or quickening effect on the
heart's action. The rhythmical action of the heart is muscular
in origin; that is to say, the heart muscle itself possesses the
inherent property of contraction apart from any nervous stimu-
lation. The nerves, although not concerned in originating the
contractions of the heart muscle, play an important part in
regulating their force and frequency in order to subserve the
physiological needs of the body. The valves of the heart allow
the blood to pass in one direction only, and thus prevent regur-
gitation. If there is any sign of regurgitation, as indicated by
the stethoscope, it is because the valves do not close completely,
which is a sign that there is something wrong in their working
action. The movements of the heart are termed systole or con-
traction, and diastole or expansion. It beats at the rate of
140 to 150 before birth, 130 at birth, during first year 125 to 135,
during third year 95 to 100, eighth to fourteenth year 85 to 90,
adult about 75, old age 65. The beats of the heart may be heard
by using a stethoscope ; the first sound, over apex of heart, is dull,
prolonged, and bocming; the second, immediately following the
first, is sharp, quick, and almost clicking, and is heard over the
base of the organ. Then follows a momentary rest, called the
period of repose, so that the heart, while apparently constantly
beating, gets a momentary rest at the end of the second beat.
The heart sounds are caused, first, by the muscular action and
vibration of the auriculo-ventricular valves and the chordae
tendineae; the second is caused by the closure of the semilunar
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 73
valves. The valves of the right ventricle are the tricuspid and
the pulmonary, and in the left ventricle the bicuspid or mitral
and the aortic. The left ventricle exerts more than twice as
much power as the right. The aortic valve consists of three
semilunar segments which surround the orifice of the aorta. They
are similar in structure to those of the pulmonary valve. The
chordae tendineae are connected to both cusps of the bicuspid or
mitral valve. The influence of the nervous system upon the
heart's action is not clearly known. The mechanism of rhyth-
mical contraction is contained within the heart itself, and it is
possible that nerve ganglia exist in the human heart as they do
in the frog's heart, and these ganglia are connected with fibres
from the pneumogastric or vagus nerves and with the sympa-
thetic system. Experiments have shown that if the fibres from
the pneumogastric or vagus nerves have been cut away the
heart's action becomes very rapid from the acceleratory action
of the sympathetic fibres. The foregoing description will prob-
ably prepare the reader for understanding the difference between
fainting and syncope when signs of collapse occur in a patient.
Syncope is when the action of the heart is impeded from loss of
blood or by anaemia of the brain centres in the medulla, through
the said action not being strong enough to pump it through the
arteries leading to the brain. This can frequently be put right
immediately by placing the patient into a postural or horizontal
position so that the blood drains towards the head by gravitation
and the heart is relieved of its vertical pressure.
Fainting is when the contractile movements of the heart are
impeded by loss of nerve power, in which case nerve stimulants
The Construction of the Arteries.
The bloodvessels which carry the blood in its circuit round the
body and into the remote parts are called arteries and veins.
Arteries are cylindrical, tubular vessels. They are elastic tubes,
and the amount of elastic tissue is greatest in the large arteries.
They contain a considerable amount of muscular as well as elastic
tissue. The muscular layer co-operates with the elastic tissue
in adapting the calibre of the vessels and the quantity of blood
they contain. For the amount of blood in the vessels is never
quite constant, and were elastic tissue only present the pressure
exercised by the walls of the containing vessels on the contained
74 OPERATIVE DENTAL SURGERY
blood would be sometimes very small and at other times too great.
The presence of a contractile element, however, provides for a
certain uniformity in the amount of pressure exercised. The
contractibility of the arterial walls fulfils a useful purpose in
checking haemorrhage should a small vessel be cut or torn, as it
assists in the closure of the cut end, and this, in conjunction with
the coagulation of the blood, arrests the escape of blood. Arteries
consist of three coats :
T. The external coat, which is the strongest layer.
2. The middle coat, which constitutes the greater part of the
3. The internal coat; its inner surface is lined with an exceed-
ingly smooth layer so that the blood may flow with the smallest
amount of resistance from friction.
The walls of the arteries are, like other parts of the body,
supplied with bloodvessels which extend for some distance into
the external and middle coat but do not reach the internal coat.
Most of the arteries also are surrounded by fibres of sympathetic
nerves, very much like ivy running round a tree. Arteries convey
blood from the left ventricle of the heart to the various parts of
the body. These vessels were named arteries from the belief
entertained by the ancients that they contained air. Galen was
the first to show that during life they contained blood.
Distribution of the Arteries.
The distribution of the systemic arteries is like a highly rami-
fied tree, the common trunk of which, formed by the aorta,
commences at the left ventricle of the heart, while the smallest
ramifications extend to the peripheral parts of the body and
Arteries are found in all parts of the body except in the hair,
nails, epidermis, cartilages, and cornea of the eye. The larger
ones usually occupy the most protected situations, running in
the limbs, for instance, along the flexor side, where they are less
likely to get strained or injured. A branch of an artery is smaller
than the trunk from which it arises, but if an artery divides into
two branches the combined sectional area of the two vessels is,
in nearly every instance, somewhat greater than that of the trunk;
and the combined sectional area of all the arterial branches
greatly exceeds that of the aorta. So that the arteries, collec-
tively, may be regarded as a cone, the apex of which corresponds
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 75
to the aorta and the base of the capillary system. The arteries
in their distribution communicate with one another, forming
what are called anastomoses, and these communications are very
free between the large as well as between the smaller branches.
The anastomoses between trunks of equal size are found where
great activity of the circulation is requisite, as in the brain for
instance. The smaller branches of arteries anastomose more
frequently than the larger, and between the smallest twigs these
anastomoses become so numerous as to constitute a close net-
work that permeates nearly every tissue of the body. The 1
arteries are dense in structure, of considerable strength, highly
elastic, and when divided they preserve, although empty, their
Degenerative Stages of Arteries.
All the arteries and, most of all, the aorta, are liable to a de-
generative process known as artero-sclerosis or athero-sclerosis.
This condition is of the greatest clinical importance, especially
in general anaesthesia. It is essentially a senile change, although
it may begin at any age and is predisposed to by kidney disease,
gout, diabetes mellitus, lead-poisoning, and a number of other
morbid states, and results in the replacement of the arterial
elastic tissue by fibrous tissue. Its chief ill-effects are two. In
the first place, it is associated with a permanent and often con-
siderable rise in the arterial blood-pressure, entailing a corre-
sponding hypertrophy of the heart ; in the second place, it weakens
the vessel walls, -rendering them liable to rupture, while, at the
same time, it is apt to lessen the calibre of the affected vessels.
The Pulse and what it reveals.
The most characteristic feature of the arteries, from a dental
point of view, is the pulse. It is the response of the arterial wall
to the changes in lateral pressure caused by each heart-beat . The
pulse is distinctly felt in the radial artery in the wrist just below
the thumb on the inner side of the continuation of the palm of the
hand. It is necessary in feeling a pulse to note the following points :
1 . Its frequency -that is, the number of pulse beats per minute.
This gives the rate of the heart-beats.
2. Its strength: whether it is a strong, bounding pulse or a
feeble beat. This indicates the force with which the heart
76 OPERATIVE DENTAL SURGERY
3. Its regularity or irregularity; irregularity may occur owing
to irregular heart's action either in force or rhythm.
4. Its tension or fulness that is, the force necessary to stop
it. This gives an indication of the state of the arterial
walls as to their elasticity and peripheral resistance.
The pulse is caused by a wave of force which passes along the
column of blood in the artery, due to a single contraction of the
heart, so that each pulsation represents a heart-beat. Each
ventricular contraction represents 3! to 4! foot-pounds. In
twenty-four hours this is estimated to equal more than 120 foot-
tons. Arterial tension is caused by the blood being forced into
the arteries at considerable pressure. The arterial walls being
very elastic permits the blood to be kept under elastic compres-
sion within them, so that when an artery is cut the blood spurts
from it in a jet. The tension, however, is modified by the rate
of the heart-beats, vasomotor nerve changes, the amount of the
blood in the system, also the motion of the chest walls in breathing.
The blood speeds through at the rate of about 35 feet per second.
Physicians in all ages have very properly attached considerable
importance to the rate and force at which the circulation is
carried on. As a measure of these conditions appeal is usually
made to the pulse, as felt by the finger placed over the artery of
the wrist. The pulse may be examined in any part where an
artery is close to the surface so that its throb can be plainly felt .
For general anaesthesia the pulse just in front of the ear on the
face is a convenient one, and also one near the ramus of the jaw
along its lower edge, but for ordinary examination the best one
is at the wrist. In feeling the pulse we must be very careful not
to flurry the patient or it will quicken the action of the heart and
render our observations valueless. We should see that there is
no pressure on the artery in any part of its course by tight
sleeves or other article of dress. By throwing the shoulders well
back it is possible to stop the pulse at the wrist. Malingerers
sometimes manage to deceive the medical man in this manner.
Practical Observation of the Pulse.
The usual way of feeling the pulse is to place the three fingers
just above the root of the thumb and the joint of wrist with your
thumb on the opposite side so as to regulate the pressure. Its
frequency may be measured by the seconds hand of a watch,
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 77
but considerable practice is required to detect and appreciate its
peculiar characteristics as indicative of various phases of disease :
its rhythm, fulness, or softness ; whether it is strong and bounding,
forcing the fingers almost away from its surface; or hard, small,
and wiry, like the vibrations of a string; whether, also, it is inter-
mittent, striking a few beats and then apparently stopping one
or two beats ; also whether the pulsations flowing into each other
are small and almost imperceptible. The information obtained
by examining the pulse is often of the most interesting kind.
In disease the pulse may acquire a degree of frequency scarcely
calculable to the touch, a rate of from 150 to 200 per minute
being in some cases recorded. A rapid pulse, strong, full, and
hard, indicates inflammation or fever ; but if small and very rapid
it points to a state of great debility. In apoplexy or when faint-
ing is impending, or in certain affections of the heart, the pulse
may be very slow. Irregularity of the pulse is a condition which,
as a rule, is full of meaning and interest. This condition is,
curiously enough, natural to some people, and when they get ill
with fever the pulse sometimes becomes quite regular. Irregu-
larity of the pulse may be dependent on a number of very
different conditions; it may be caused by disease within the
head, or by disease of the heart, or it may be the result of simple
disorder of the stomach, or of general debility. It does not
follow because it is irregular that there is any serious danger.
Smoking in excess or too generous use of stimulants may cause it.
Again, a pulse may be intermittent. When the motions of the
artery are unequal in number and force, a few beats being from
time to time more rapid and feeble than the rest, we say the
pulse is irregular; but when from time to time a pulsation is
entirely left out, we say it is intermittent. Frequently the
intermission is perfectly regular, a pulsation being missed every
fourth, tenth, or twentieth beat. When the intermissions are
frequent, say every four or six beats, they are more likely to be
regular. Intermittency of the pulse may be due to many
diseases, but it is not always of grave importance, for many
trivial causes may produce it. It is rare in young children, but
after middle age it is not at all uncommon. In some cases it is
habitual, in others occasional only, and induced by some tem-
porary constitutional derangement. Tobacco, tea, and stimu-
lants are often responsible for this condition, or it may have a
serious significance of the heart's action, brought about by
78 OPERATIVE DENTAL SURGERY
rheumatic fever or other serious complications. Another im-
portant quality of the pulse is what is called hardness or incom-
pressibility. We find that we can scarcely abolish the pulsation
by any degree of pressure; the blood still forces its way through
the artery beneath our fingers. Sometimes it is felt to strike a
large portion of the finger, and we then say it is hard and full.
When it strikes a very narrow portion of the surface of the finger,
it is compared to a thread, and is a small pulse. A full pulse
occurs in people who are plethoric, and also in the early stages
of acute disease. A weak pulse denotes impoverished blood and
an enfeebled condition of the system.
Capillaries or Mesh formed by the Endings of Arteries and
the Beginnings of Veins.
The arterioles are the very fine and numerous endings of the
arteries, which pass into capillary bloodvessels and are as fine as
hairs, when they almost disappear and again become larger to
form the capillaries that are the commencement of the veins
which carry the blood back to the heart.
TABLES WITH REFERENCE TO THE PULSE.
FREQUENCY OF PULSE.
At birth . . . . 130 to 150 times per minute.
First year .. .. 100 to 130
Seventh year . . 72 to 90 , , , ,
Fifteenth year . . 80 to 85 ,, ,,
Thirty-fifth year . . 69 to 75 ,, ,,
Seventieth year . . 50 to 60 ,, ,,
FREQUENCY OF RESPIRATION.
First year . . 35 times per minute.
Second year 25
Fifteenth year . . 20 ,,
Above twenty . . 18
TEMPERATURE OF THE BODY.
Normal .. .. 97 1- to 98 1 Fahrenheit.
Feverishness . . 99 to 100 , ,
Slight fever . . . . 100 to 101
Moderate fever . . 102 to 103 ,,
High fever . . . . 104 to 105
Intense fever 105 ,,
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 79
TEMPERATURE IN RELATION TO PULSE.
Temperature of 98 Fah. corresponds to pulse of 60