glenoid cavity, and the petrous portion. Its wide surface takes
the origin of the temporal muscle.
OPERATIVE DENTAL SURGERY
The mastoid portion is situated just behind the orifice of the
passage of the ear.
It is nodular in shape and forms the corner
at the back and base of the cranium. It is sometimes the seat
of serious septic trouble. The interior is of a coarse, spongy
structure, and is ultimately connected with the interior of the ear.
3 C >
FIG. 24. THE TEMPORAL BONE.
The styloid process, so called from its resemblance to a pen, is
a peg-like bone which is inserted almost immediately behind and
inside the neck of the mandible and immediately beneath the
orifice of the ear. It looks like a long, thin root of a tooth. It
varies in length and becomes hard as age advances in different
people. On its extreme end is the origin for the stylo-mandibular
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 55
ligament. The petrous portion derives its name from the hard-
ness of its bone. It contains the ear and runs along towards
the centre of the base of the cranium, both bones meeting within
an inch of each other. On the extreme top end of the petrous
portion is a depression in which the gasserian ganglion lies. The
temporal bone joins the parietal, sphenoid, occipital, and malar
The sphenoid bone is so called because it is wedged in at the
base of the skull and forms a strong supporting beam to the
bones of the cranium and face. It not only enters into the
formation of the inner base of the cranium, the orbits, the temples,
and the nasal passages, but it is also connected with all the
cranial bones and many of the facial bones. Its general shape
bears a remarkable resemblance to a bat with extended wings,
with a body or central part, two greater wings, two lesser wings,
and the pterygoid processes which make the legs of the bat
(Fig. 25). This bone has several foramina or apertures which
transmit bloodvessels and nerves from the brain; but there are
three important ones for us to notice, because they transmit the
three great branches of the trigeminal or fifth pair of nerves.
1. The Sphenoidal Fissure.
2. Foramen Rotundum.
3. Foramen Ovale.
These apertures are situated in the top part of the sphenoid
bone, which forms part of the floor of the cranium.
The pterygoid process or plates are situated on the lower
outside part of the legs and stand out at the corners. The
process consists of two plates, which take the origin of the internal
and external pterygoid muscles. The pterygoid processes are
closely joined to the palate bones, and also act as buttresses to
support the superior maxillary bones and form a frame for the
posterior openings of the nose.
Description of the Lower Jaw for Practical Purposes.
The inferior maxilla, also called the mandible or lower jaw,
is a separate bone, complete in itself, and is not attached by a
suture or a join to any neighbouring bone. Its extreme ends
shape off to a very small round shoulder or condyle, called the
neck or condyle, which acts as a joint or hinge for its working,
OPERATIVE DENTAL SURGERY
and fits or rather oscillates in the glenoid cavity, which is situated
immediately in front of the centre of the ear, where it can be felt
by touching it during mastication. About an inch and three-
FIG. 25. THE SPHENOID BONE.
origin of superior
Exhibited in two positions. The upper one shows the whole of its cerebral
or brain surface; the lower one is viewed vertically, showing the top
outline of cerebral surface, the sides which carry the pterygoid
muscles, and the central lower part which constitutes the roof and
sides of the nasal cavity.
quarters in front of the neck is a similar spike-shaped end called
the "coronoid process," but it does not act as a joint (see Figs.
26 and 27).
The slipping forward of the neck or condyle causes the accident,
which we occasionally come across, termed dislocation of the jaw.
Dislocation may be either unilateral or bilateral. If one side
slips out it is unilateral, and is usually soon put back into its
socket. But if both sides are out it is called bilateral, and is
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 57
often a very difficult business to reduce or get into place again.
It is soon put right if the condition is' understood. The neck or
condyle slips out of its socket, and the contraction of the various
powerful muscles already indicated pulls it up into the space
FIG. 26. THE SUPERIOR AND INFERIOR MAXILLARY BONES OF A CHILD
AGED 5^ YEARS.
The cortical or outer plates of the bones, and also part of the inner spongy process,
have been cut away in order to show the relative positions of the first and
second dentitions, and also the principal points of the maxillary bones.
I, Nasal process; 2, antrum; 3, division, showing solid part of maxilla.
58 OPERATIVE DENTAL SURGERY
between the malar rail, and at the same moment this movement
tilts the whole jaw downwards in front, and the patient presents
a distressing appearance. By putting a napkin on the back
teeth in the lower, then standing behind and over the patient,
FIG. 27. THE SUPERIOR AND INFERIOR MAXILLARY BONES OF A CHILD
AGED 5^ YEARS.
Viewed from behind. (Photograph taken from the same specimen as in
and forcibly gripping the sides of the jaw with thumbs on the
napkin and forcing it downwards and backwards so as to over-
come the powerful contraction of the muscles, at that moment
it will slip into its place in the sockets of the glenoid cavity (see
Figs. 32 and 34).
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 59
The most important feature of the mandible, however, which
we should not miss, is the inferior dental canal. This is a most
important part, and is always likely to be involved in the ex-
traction of lower teeth as well as in root treatment. It carries
the very large nerve called the inferior dental nerve, and the
large bloodvessels called the inferior dental artery and vein.
They enter the canal through a large foramen or opening at a
point on the inner or tongue side of the jaw about one inch,
behind the lower wisdom teeth and a little above the level of
them. It then dips down into the basal part of the jaw, just
missing the roots of the wisdom teeth and runs about a quarter of
an inch below the roots of the molar and bicuspid teeth until it
reaches the second bicuspid. At this spot it branches into two
parts, the larger branch coming out at a hole called the mental
foramen, and enters into the corners of the lower lips. This
branch sometimes absorbs cocaine or other alkaloid solutions,
especially if containing much adrenalin, and will cause local
anaesthesia in this part, and the patient complains of something
the matter with the lip. The other branch, called the incisive
branch, continues from the second bicuspid into a much smaller
canal in the jaw, in a line with the back part of the canal, and
ends under the central teeth. The nerves and vessels of one side
do not have any connection with those of the other side. The
lower jaw is really a flattened tube. The outside part is called
the cortical plate, and the interior the alveolar process and the
spongy process. There are fourteen pairs of muscles attached
to the mandible.
Description of the Upper Jaw for Practical Purposes.
The superior maxilla or upper jaw is of quite a different form,
and, beyond the fact of its containing the upper teeth, it has no
similarity to the mandible. In the first place it is much smaller
in width and has not anything like the mass or depth of the
lower. Of course this is accounted for by the fact that it is
strengthened by being connected with several neighbouring
cranial bones, and is also strengthened by the palatal bone which
is an extension of the upper jaw, each forming a floor to the nasal
cavity and a vault to the mouth. These bones made up of
one on each side joining in the centre of the face and called the
superior maxillae, are the most important bones of the face
6o OPERATIVE DENTAL SURGERY
excepting the mandible, and form, by their union in the centre
of the mouth, the whole of the upper jaw. Each side assists in
the formation of three distinct cavities, viz.:
The roof of the mouth,
The floor and outer wall of the nose, and
The floor of the orbit or eye socket.
Each bone consists of a body and four processes, viz.:
Zygomatic, Alveolar, Frontal, Palatal (Figs. 28 and 29).
The Antrum constitutes the Body of the Upper Jaw.
The body of the jaw is somewhat pyramidal in shape, and
contains a large cavity called the antrum, or the maxillary sinus.
Also five surfaces as follows:
1. An anterior or facial surface from the floor of the orbit
forming the front of the face on each side to the alveolar border,
and slightly concave, excepting at the eminences above the roots
of the teeth.
2. A posterior or zygomatic surface, downward, backward,
and outward, forming the sides of the lower part of the face from
just under the cheek prominence to midway between the nose
and ear. It ends just against the coronoid process of the lower
jaw, and just inside it.
3. The superior or orbital surface is smooth and triangular,
and forms the greater part of the floor of the orbit.
4. The palatal surface which extends from the alveolar border
on one side right across to the border of the other side.
5. The internal surface, which extends from the floor of the nose
and runs up each side, leading to a small opening just below the
floor of the orbit. This opening is not large, and is the only
opening into a large roomy cavity or chamber called the antrum.
This cavity extends from the canine, or first bicuspid, right back
to beyond the wisdom teeth, a distance of about one and a half
inches to one and three-quarter inches. It also rises from the
floor immediately above the roots of the bicuspids right back to
the wisdom teeth upwards to immediately underneath the orbits.
In children these measurements are much less. The floor of the
orbit is so thin that any swollen condition of the eye would
depress it on to the antral space. On the other hand, if the
antrum became full of pus, as it frequently does in empyema,
which is an inflammatory condition of the antrum, and also in
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 61
many nasal affections, the floor of the orbit would be pushed up.
The nasal wall of the antrum is also exceedingly thin. The cavity
itself would hold a quantity of pus or liquid if it were shut in,
which is quite possible if the only opening we have described is
blocked up by a swollen condition of the nasal mucous membrane
at that point, to the extent of from a teaspoonful in a child to
two drachms in an adult (see Fig. 34).
OPERATIVE DENTAL SURGERY
The extent of the antrum on each side leaves very little actual
solid bone in any part of the upper jaw (see Figs. 32 and 34). It
is fairly thick in front from canine to canine, but that is all. At
3 o 3 tj c <^ 5
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N c N S U o S
every other part it consists of a plate only, of more or less even
thickness, and indeed, at a point in the region of the second
bicuspids in the palate right at the top at each side, a point
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 63
could easily be pushed into the chamber. This spot is of no
utility for draining purposes, as it is right above the floor, and
there is also great danger of striking the nerves and bloodvessels
which run from the posterior palatine canals towards the anterior
palatine canal. The importance of the antrum to the dentist is
in extraction operations, in which an abscessed root might be
pushed upwards in its alveolar socket and disappear, where it
would be floating about with little chance of its being rescued
without an operation of some kind, which might be simple or
complex as the subsequent circumstances turned out to be. Or,
again, in root treatment, probes, nerve canal drills, powerful
antiseptics, etc., could easily produce inflammatory trouble in
the antrum owing to its immediate vicinity to the roots of the
teeth. Or, again, some judgment is necessary on the part of the
operator as to whether he should interfere by operating in its
vicinity, as there might already be a blocking of the small and
only opening leading from the antrum to the nose, caused by a
cold or empyema. His work might be blamed for causing the
condition for which he would not in any way be responsible. To
summarize the parts of the superior maxillae or upper jaw, it
stands thus ^each side consists of:
3 CAVITIES. 4 PROCESSES. 5 SURFACES.
Roof of Mouth. Zygomatic or side. Anterior or facial.
Floor and outer wall Frontal. Posterior or side of
of nose. Alveolar. face.
Floor of the orbit. Palatal. Superior or orbital.
Internal or nasal.
The other important parts of the maxilla, as far as operating
is concerned, are the posterior and anterior palatine canals (see
The posterior palatine canal is situated at the foramen on the
surface of the palate at a spot approximating to the apex of the
palatine root of the wisdom tooth. It is formed by the union of
the palatal bone with the maxilla. The foramen beginning at
the palate is in the palatal bone and penetrates it for about five-
eighths of an inch, when the canal continues behind the antral
part of the maxilla by a groove contained in it and a groove in
the palatal bone. Near the top of the external wall of the antrum
64 OPERATIVE DENTAL SURGERY
the canal opens out into the spheno-maxillary fissure which is
formed by a large space between the sphenoid bone and the
The palatal bones are two slender bones, each one shaped like
a rough I I, the two bones being placed in this position. They
are wedged between the sphenoid and maxillary bones, the stem
of the L forming the rim of the outer nasal well. The base forms
the floor of the nose at the back part, while the underneath
surface forms the back part of the palate and the attachment for
the soft palate and the palatal muscles.
On the posterior surface of the maxilla, on the outer wall
approximating to the face and about two-thirds of the height
of the maxilla, foramina may be seen which transmit the pos-
terior dental nerves which run down to supply the roots of the
molar teeth (see chapter on Nerves). The anterior palatine
canal is situated immediately behind the upper central teeth.
The canal is formed by a groove situated in the right and left
maxilla. The palatal foramen is very large, but becomes some-
what smaller as it runs upwards, and ends with two smaller but
short canals called the foramina of Stensen, forming the letter
Y with a long stem. There are several small foramina, some
situated in the front of, and also behind, the canal, but branching
from the canal, which transmit the naso-palatine nerves, and are
called the " foramina of Scarpa." Great care must be taken to
avoid plunging a hypodermic needle into the anterior palatine
canal, because it is usually situated right against the necks of the
central teeth. The same precaution must be used towards the
posterior palatine canals, although they are not so contiguous to
the wisdom teeth.
The superior maxillary bones are attached to about nine bones :
two of the cranium viz., the frontal and ethmoid, and seven
of the face viz., the nasal, malar, lachrymal, inferior tur-
binated, palatal, vomer, and sometimes the sphenoid.
The Nature of the Gums, with Indications where Care is
The gums consist of the linings that cover the external sur-
faces of the jaws within the oral cavity. They are composed of
a dense fibrous tissue closely connected with the peridental
membrane of the alveolar processes and surrounding the necks
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 65
of the teeth. They are covered by smooth and vascular mucous
membrane, which has a limited sensibility. Around the necks
of the teeth this membrane presents numerous fine papillae, and
is reflected into the alveoli, where it is continuous with the perios-
teal membrane lining the sockets. It consists of the mucous
membrane, which is the lining or the skin of the internal passages
of the body. Its surface is covered with its secretion called
mucus, which is of a gummy, tenacious consistency, and which
serves to protect it from foreign substances with which it is
brought into contact. The mucous membrane consists of four
The epithelium is the outer layer, and consists of two mem-
branes called the "corneous " and the "Malpighian lining."
The basement membrane is a thin structureless lining, which
separates the epithelium from the corium.
The corium is the true mucous membrane.
The submucous membrane is next to the bone, and is termed
The gums consist cf that part of the mucous membrane which
surrounds the teeth, and which is thicker than the other parts.
It will be seen that the mucous membrane is intimately attached
to the bone, and there is danger of a suppurating character if it
should be badly torn in extraction of teeth, or lifted away by too
forcible hypodermic injection, too strong rubber suction discs in
the palate, and undue interference with the gums when regulating
children's teeth. When the gums are thus lifted or peeled away
from the bone a thick viscid serum collects, which will some-
times spread its way along the bone. Instances of this can
sometimes be seen in a case of a palatal abscess, where, instead
of breaking at a fistulous opening or gumboil, it forces up the
mucous membrane, and there is danger of it falling into the
A DESCRIPTION OF THE IMMEDIATE NEIGHBOURING
PARTS OF THE TEETH (Continued)
THE CIRCULATORY SYSTEM.
IT is very important that the dental operator should understand
where the bloodvessels of the mouth lie, but it is infinitely more
incumbent that he should constantly bear in mind the nature of
the fluid that passes through them ; also what sequelae might prob-
ably arise from infection when a bloodvessel is opened either by
operation or by accident. When injections are made these blood-
vessels are frequently punctured, whereas by a little observation
it will be noticed that superficial vessels vary in number and
position with every patient.
On the labial or outside part of the gums the superficial veins
can easily be seen lying in the upper or lower half of the gums
between the lighter pink zone around the necks of the teeth up
towards the sulci, or that part of the lips or cheeks which folds
over and is composed of loose cellular tissue, which is not only
dangerous for plunging hypodermic needles into, but is useless
for securing local anaesthesia with the small doses that the dental
operator should use. On the lingual side of the gums there is
only a very limited zone for safe hypodermic injection, which is
just around the necks of the crowns of the teeth for a depth of
about a quarter of an inch.
When describing the upper jaws or maxillae we noted the
position of the posterior canals which have a large opening in the
palatal surface of the bone just in the region of the apices of the
wisdom teeth. They are situated on the level of the floor of the
palatal bone, at a point where it curves down towards the wisdom
teeth. In some jaws this spot is three-quarters of an inch from
the gum margin, in others it is about half an inch. Its bore
or diameter is about one-eighth of an inch and is somewhat
larger at its immediate opening at the surface of the palate.
Again, there is the anterior palatine canal, which is situated
immediately behind the upper central teeth. This is much
IMMEDIATE NEIGHBOURING PARTS OF THE TEETH 67
larger than the posterior canals in bore or diameter, and is in
immediate danger of being punctured or damaged. Thesexanals
allow the passage of an artery, vein, and nerves. From the
posterior canals emerge bloodvessels, which run forward in a
groove on the surface of the hard palate.
The position of the descending palatine artery should be borne
in mind when using dangerous instruments such as a sharp
elevator, as it is in danger of being wounded and may give rise
to formidable haemorrhage, while in rare cases it has been found
necessary to plug the canal itself in order to arrest the bleeding.
We are constantly aware of the readiness which the tissues
have of bleeding. The amount of blood that appears may be
much or little; if much, it probably comes from bloodvessels
which could be seen easily with the naked eye, and, on the other
hand, if there is little blood it probably comes from bloodvessels
of so small a size that they are termed arterioles, which become
finer still and are called capillaries. In the extraction of teeth
blood flows in many degiees of force and quantity. When the
bleeding has subsided, the clot becomes the centre from which
repair of the tissues commences, and which is ultimately com-
pleted through the agency of the blood, which is constantly
bringing materials for the work, and which also carries away the
waste products from the process. The same thing is going on in
every part of the mouth in health, and also in every part of the
body. We shall therefore defer the location of the bloodvessels
of the mouth to another chapter, and briefly describe the ap-
paratus of the circulatory system and the fluid that passes through
it, which is called blood. The following description has been pre-
pared for our readers from Gray's " Anatomy," Halliburton's
" Physiology," and other standard works.
Some of the Foregoing Reasons should Lead us to Enquire
as to the Nature of the Circulatory System.
Bloodvessels are divided into three kinds, known as arteries,
capillaries, and veins. They are entirely different in their func-
tions, and form, with the heart, the blood vascular system. The
branch of anatomy which deals with the circulation of the blood
is called angiology. This comprises a description of the vascular
system of the body and is divided for descriptive purposes into :
1. The blood vascular system, and
2. The lymph vascular system.
68 OPERATIVE DENTAL SURGERY
The blood vascular system consists of the heart and blood-
vessels for the circulation of the blood.
The lymph vascular system consists of lymphatic glands and
vessels, through which a colourless fluid called lymph circulates.
It must be noted, however, that the two systems communicate
with each other, and are intimately associated developmentally.
The Heart and its Function.
The heart is the central organ of the blood vascular system,
and consists of a hollow muscle; by its contraction the blood is
pumped to all parts of the body through a complicated series of
tubes called arteries. The arteries undergo enormous ramifica-
tion in their course throughout the body, and end in very minute
vessels called arterioles, which in their turn open into a closely
meshed network of microscopic vessels called capillaries. After
the blood has passed through the capillaries it is collected into a
series of vessels which in turn open out into larger ones ; these are
called veins, by which it is returned to the heart. The passage
of the blood through the heart and bloodvessels constitutes what
s termed the circulation of the blood.
The human heart is divided by a wall into right and left halves ;
each half is further divided into two cavities : an upper, called the
auricle, and a lower, termed the ventricle. The heart, therefore,
consists of four chambers, called the right auricle and the right
ventricle, forming the right half; then the left auricle and the
left ventricle, forming the left half.
The auricles are receiving chambers and the ventricles are dis-
tributing ones. The right half of the heart contains venous or
impure blood; the left contains arterial or pure blood. From
the cavity of the left ventricle the pure blood is carried into an
artery of tremendous capacity called the aorta, through the large
branches of which it is distributed to all parts of the body, with
the exception of the lungs.
The Object of the Circulation of the Blood to nourish and