THE FACE.
The bony structure of the face.--_Orbital cavities_: margins;
cavities.--_Nasal fossæ_: anterior orifice.--Prominence of the
_cheek_; malar bone and its processes.--_Upper jaw._--_Lower
jaw_; body; ramus; sigmoid notch, coronoid process, and condyle:
variations with age.--The _teeth_: parts; names (incisors,
canines, premolars, molars), number; relative dimensions of
incisors.--Articulation of the lower jaw.--The face and skull
as a whole with regard to form.--_Facial angle of Camper_; its
measure; its proper value according to race; its exaggeration
in the antique.--Proportions: the head as a common measure:
law of eight heads; variations according to the height of the
individual; point which corresponds to the middle of the body.
_The Face._--Instead of describing the bones of the face separately we
will group them together around the cavities which they circumscribe
and the prominences which they form. We will therefore study
successively the _cavity of the orbit_, the orifice of the _nasal
fossæ_, the prominence of the _cheek-bone_, and, lastly, the region of
the _mouth_, along with which we will describe the _teeth_, the _lower
jaw_, and its articulation with the base of the skull.
_The orbits._--The orbits are two cavities situated symmetrically one
on each side of the upper portion of the face below the forehead. Each
of these cavities is formed like a pyramid with four sides, of which
the apex penetrates backwards towards the cranial cavity, and of which
the base, turned forwards, forms the orbital opening. This opening, or
_orbital margin_, is of quadrilateral form with rounded angles (Fig.
58), limited by an internal border (7) and an external border, both
almost vertical, by a superior border (3) and an inferior border, both
oblique, from above downwards and outwards.
[Illustration: FIG. 58.
THE BONY STRUCTURE OF THE FACE.--1, the frontal bone;--2,
the nasal eminence;--3, supra-orbital notch;--4, the optic
foramen;--5, the sphenoidal fissure;--6, the spheno-maxillary
fissure;--7, the lachrymal groove;--8, the partition and opening
of the nasal fossæ;--9, the infra-orbital foramen;--10, the
malar bone;--11, the symphysis of the jaw;--12, the mental
foramen;--13, the ramus of the lower jaw;--14, the parietal
bone;--15, the coronal suture;--16, the temporal bone;--17,
the temporo-parietal suture;--18, the great wing of the
sphenoid;--19, the origin of the temporal ridge;--20, the
zygomatic arch;--21, the mastoid process.]
The superior border is formed by the supra-orbital arch of the
frontal bone (3, Fig. 58) previously described, which presents the
supra-orbital notch; the inferior border is formed by the _superior
maxillary_ and _malar_ bones; a little below its centre is a hole,
called the _infra-orbital_ foramen (9, Fig. 58), which is placed in
the upper jaw almost in the same vertical line as the supra-orbital
notch above the orbit (page 168). The internal border is formed by the
junction of the internal angular process of the frontal bone with the
ascending (nasal) process of the superior maxilla (Figs. 56 and 58).
Behind the inferior part of this border is a deep groove, called the
_naso-lachrymal groove_ (7, Fig. 58), for the accommodation of the
lachrymal sac (for the tears), which is the commencement of a canal
(_naso-lachrymal canal_) connecting the orbit with the corresponding
nasal fossa, and serving to transmit the nasal duct. Finally, the
external border is formed by the junction of the external angular
process of the frontal with the superior process of the _malar bone_,
or bone of the cheek (10, Fig. 58; 14 and 15, Fig. 56).
The cavity of the orbit has for its walls the osseous plates belonging
to the frontal (superior wall) and the several bones of the face we
have previously mentioned when describing the orbital opening. We
need not enter here into the description of these surfaces and of the
several special bones which compose them. We shall only say that the
internal wall is directed from before backwards, while the external
wall is oblique, from behind forwards and from without inwards. We
note, lastly, at the deepest part (towards the apex) of the cavity,
three apertures, by which the orbit communicates with deeper cavities;
first, a circular orifice called the _optic foramen_ (4, Fig. 58);
then, on the outer side of these, two fissures directed outwards, one
obliquely upwards (_sphenoidal fissure_, 5, Fig. 58), and the other
obliquely downwards (_spheno-maxillary fissure_, 6, Fig. 58). The two
first communicate with the cranial cavity; the last-named fissure leads
into the spheno-maxillary fossa.
The _orifice of the nasal fossæ_ (8, Fig. 58) is situated in the middle
of the face below the level of the orbits. It is somewhat heart-shaped
(with the base downwards); it is bounded below by the two superior
maxillary bones which unite in the middle line and form the _anterior
nasal spine_, upon the sides by the same bones, and above by the two
small _nasal_ bones (Fig. 56, page 165) wedged in on each side of the
middle line between the nasal processes of the maxillary bones, and
articulating above with the nasal notch of the frontal bone.
Below, and to the outer side of each orbit, is the prominence of the
cheek formed by the _malar bone_ (10, Fig. 58). This bone is formed
like a star with four rays. The _superior_ or _orbital process_ (15,
Fig. 56) joins the external angular process of the frontal bone; the
_anterior process_ (17, Fig. 56) forms with the superior maxillary
the inferior boundary of the orbit; the _posterior_ or _zygomatic
process_ (16, Fig. 56) is directed backwards to form by its union with
the zygomatic process of the temporal bone, the _zygomatic arch_; the
_inferior_ angle is reduced to a prominent margin which joins with the
body of the bone to form the _prominence of the cheek_. This prominence
is due to the projection of a _malar process_ of the upper jaw on which
the malar bone is fitted.
There remain now only two bones to examine on the skeleton of the
face--namely, the two bones which bound the cavity of the mouth and
support the teeth: these are the superior and inferior maxillary or
jawbones. The _superior maxillary bone_ (18, Fig. 56) has been in a
great measure described already in relation to the orbital and nasal
openings. The following points remain to be noticed: 1. The external
surface is divided by a ridge descending from the malar process, into
two surfaces--one outer, belonging to the zygomatic fossa, and the
other anterior, appearing on the face. The facial surface is again
subdivided into two smaller fossæ--the _canine fossa_, in which occurs
the infra-orbital foramen, and the _incisive fossa_, above the incisor
teeth--by a ridge (the _canine ridge_) which is formed by the prominent
fang of the canine tooth. 2. The inferior or _alveolar_ border presents
a series of cavities for the lodgment of the roots of the upper
teeth. The presence of these cavities is marked on the surface of the
alveolar border by a series of prominences separated by depressions
corresponding to the partitions between the alveoli.
[Illustration: FIG. 59.
THE INFERIOR MAXILLARY BONE (side view).--1, the body of the
inferior maxillary bone and its external oblique line;--2,
the ramus;--3, the symphysis of the chin;--4, the mental
foramen;--8, the angle of the jaw;--10, coronoid process;--11,
the condyle;--12, sigmoid notch;--I, incisor teeth;--_c_, canine
tooth;--_b_, bicuspid;--_m_, molar teeth.]
The _inferior maxillary bone_ or _mandible_ (Fig. 59) requires more
detailed consideration than the other bones of the face, as it takes so
direct a share in the surface form that we may say that all the details
of its shape are marked in the configuration of the chin and lower
parts of the cheeks. It is originally composed of two distinct halves,
one right and one left, which are joined together in early life in the
middle line of the chin to form the symphysis of the chin, or _mental
process_ (11, Fig. 58). It is sufficient to describe one of these
halves as we see it in a side view of the skull (Fig. 56).
We see that each half is formed of two strong osseous plates joined
together at an angle more or less approaching a right angle, of which
the prominence directed downwards and backwards is called the _angle
of the jaw_. The horizontal portion of the bone is called the _body_;
the vertical portion is the _ramus_.
The _ramus_ consists of a flat external surface, which is continued
below into the body of the bone (2, Fig. 59). Its posterior border is
thick, and is continued downwards to the angle of the jaw. The anterior
border, which is thinner, is grooved, and terminates by joining below
the upper alveolar border of the body of the bone. The borders of
the groove join the oblique lines on the surfaces of the body of the
bone. The superior border is divided by a deep notch (_sigmoid notch_,
12, Fig. 59) into two very prominent parts. The posterior prominence
is thick, and forms the neck, surmounted by the articular head, or
_condyle_, of the jaw (11, Fig. 59), for articulation with the temporal
bone; the anterior prominence is in the form of a triangular plate,
and bears the name of the _coronoid process_ (10, Fig. 59); it gives
insertion to the temporal and masseter muscles.
The _body_ of the lower jaw extends from the angle to the _symphysis_
of the chin (3, Fig. 59); it has an external surface marked by an
oblique line, above which is an orifice (12, Fig. 58; and 4, Fig. 59)
called the _mental foramen_, placed in the same vertical line as the
supra-orbital notch and the infra-orbital foramen. It is situated about
the level of the second premolar tooth. The inferior border of the bone
is thick and rounded; its superior _alveolar_ border presents sockets
for the teeth, and externally a series of prominences and depressions
corresponding to the alveoli and the intervals between them.
The character of the lower jaw changes with age; in the infant,
the angle is very obtuse and but slightly prominent: in the adult
it becomes almost a right angle: in the aged the form of the jaw is
changed by the loss of the teeth and by the absorption of the alveolar
border, causing a diminution of height in the body of the bone. In
order, therefore, to bring the two jaws in contact with one another,
the lower jaw requires to move strongly forwards and upwards, whence
occurs a characteristic prominence of the chin in the aged, which seems
to project upwards and forwards to meet the prominence of the nose.
The teeth of the adult are altogether thirty-two in number--eight in
each lateral half of each jaw. Each tooth is composed of a part fixed
in the alveolar cavity called the _root_, and a free part called the
_crown_. The form of the crown permits the division of the teeth into
four distinct classes, which in each half of the jaw are arranged in
the following manner, beginning from the median line:--Two _incisors_
(I, Fig. 59), one _canine_ (_c_, Fig. 59), two _premolars_, or
_bicuspids_ (_b_, Fig. 59), and three _molars_ (_m_, Fig. 59)--total,
eight. Situated at the most external and posterior portion of the
dental arch, the premolar and molar teeth are hidden by the cheeks, and
we need only mention that they are characterised by a crown formed of
numerous tubercles (two for the premolars, four or five for the molar
teeth). On the other hand, the canine and incisor teeth are easily seen
when the lips are separated. The _canine_ teeth are characterised by a
conical crown with a sharp extremity, which is very large and prominent
in the carnivora--_e.g._, in the dog (whence the name of canines).
The _incisors_ present a crown flattened from before backwards, and
rectangular in form (square). Their relative size is so constant that
it should be stated here. The two largest are the median incisors of
the upper jaw; next in order come the lateral incisors of the upper
jaw, then the lower lateral, and finally the lower median incisors,
which are the smallest. The lower incisors, besides being smaller, are
characterised by their chisel-like cutting edge, which is bevelled at
the expense of the outer surface.
The articulation of the lower jaw with the skull, or _temporo-maxillary
articulation_, is formed by the articulation of the condyle of the jaw
(11, Fig. 59; and 29, Fig. 56) with the glenoid cavity of the temporal
bone--a cavity placed in front of the external auditory meatus, and
behind the _articular eminence_--the transverse root of the zygomatic
process (page 169). This _glenoid cavity_, together with the articular
eminence, is lined with cartilage, and is separated from the condyle
of the jaw by an inter-articular fibro-cartilage. These structures are
enclosed in a fibrous capsule which surrounds the articulation, and is
strengthened on the outer side by a stout external lateral ligament,
attached obliquely from a tubercle at the root of the zygoma downwards
and backwards to the outer side of the condyle of the jaw. Therefore,
when the jaw is depressed by a movement of rotation of the mandibular
condyle upon its axis, this external lateral ligament is made tense,
and draws the condyle forward, causing it to leave the glenoid cavity
and come in contact with the articular eminence. Thus, when the mouth
is widely opened (the lower jaw being greatly depressed) there is
a displacement of the condyle of the jaw forwards, which is easily
seen in thin subjects, and which should be noted here with its own
particular mechanism.
The face, as a whole, presents a special interest when we compare its
configuration with that of the cranium, in various individuals and
races. In general, the more prominent the skeleton of the face the less
the cranium (the forehead) is developed. This was the idea of Camper, a
Dutch anatomist and artist, about the middle of the eighteenth century.
[Illustration: FIG. 60.
THE MEASUREMENT OF THE FACIAL ANGLE (goniometer applied to a
skull).--1, the inferior horizontal plane of the goniometer;--2,
movable piece with a pin introduced into the auditory
meatus;--4, graduated circle;--5, the oblique plane attached
below by a hinge to the horizontal;--6, the rack for placing the
bar (7) on the prominent part of the forehead.]
[Illustration: FIG. 61.
THE FACIAL ANGLE OF A SKULL OF THE CAUCASIAN RACE (after
Camper).--_a b_ and _c d_, the lines which mark this angle
(see the text);--1, the auditory meatus;--2, anterior nasal
spine;--3, the most prominent part of the forehead.]
Camper proposed to measure the relative proportions of the cranium and
face by the angle which the plane of the profile of the face makes with
that of the base of the skull. This facial angle has since been the
subject of much study on the part of anatomists and anthropologists,
who have modified and perfected the process of measurement. It will be
sufficient here to show what Camper’s idea was, and that, apart from
anatomical considerations, he designed to furnish artists with a means
of giving character to the different physiognomies of men and animals.
This angle is determined by two planes (upon a head seen in profile, by
two lines): one plane, which we may call horizontal, proceeds from the
external auditory meatus to the anterior nasal spine, and corresponds
to the inferior border of the orifice of the nasal fossa (1, Fig. 60;
and _a_, _b_, Fig. 61); the other, directed obliquely upwards and
backwards, is at a tangent below to the prominence of the incisor
teeth, and above to the most prominent part of the forehead (_c_,
_d_, Fig. 61). Fig. 60 gives an idea of the apparatus with which we
measure the facial angle at the present day. It represents the facial
goniometer of Jacquart. The mode of measurement here differs from that
employed by Camper, in that the inferior or horizontal plane passes
forward not by the nasal spine, but by the prominence of the incisor
teeth.
Figures 61 and 62, which are reproduced from those of Camper, show on
the one hand that while the facial angle is never equal to a right
angle, it approaches to it in the best types of the white race.
[Illustration: FIG. 62.
THE FACIAL ANGLE OF A NEGRO (after Camper). The figures are the
same as in the preceding.]
The ancients sought by an exaggeration to idealise the profile of the
human face, and by increasing the fulness of the forehead they have
given to heads of gods and heroes a facial angle as large as ninety
degrees (Fig. 63). These figures show, also, the decrease of the facial
angle in proportion as we pass from the white to the yellow and black
races:--“The angle which the facial line or characteristic line of the
visage makes,” said Camper, “varies from seventy to eighty degrees in
the human species. All who raise it higher disobey the rules of art
(from imitation of the antique); all who bring it lower fall into the
likeness of the monkeys. If I cause the facial line to fall in front
I have an antique head; if I incline it backwards I have the head of
a negro; if I cause it to incline still further I have the head of a
monkey; inclined still more, I have that of a dog; and, lastly, that of
a goose.”[6] The figures which explain these ideas are as follows:--The
facial angle of Camper averages 80 degrees in the Caucasian race; 75
degrees in the yellow, or Mongol; 60 to 70 degrees in the Negro; 31
degrees in the great monkeys (gorilla); lastly, 25 degrees in the head
of a Newfoundland dog.
[Illustration: FIG. 63.
THE FACIAL ANGLE OF AN ANTIQUE HEAD (Apollo
Belvedere)--(Camper).]
* * * * *
In our study of the various segments of the limbs we have seen that
some of them have been chosen, in different systems of measurement, to
serve as a common measure for these limbs, and for the entire body.
Thus we have spoken of the canons which respectively take as a unit
the _hand_ (contained about ten times in the height of the body), the
_foot_ (contained a little more than six times in the total height),
the _middle finger_ (contained nineteen times), &c., &c. It is true,
also, that the head--_i.e._, the vertical distance from its summit to
the base of the chin--may be taken also as a common measure. This was
done long ago. Vitruvius, speaking of the proportions of the human
body, states that the height of the head should be the eighth part of
the whole body. Leonardo da Vinci, Albert Dürer, and J. Cousin have
followed the rule of the Latin author; and the law which makes the
head the eighth of the total height has for a long time past become
classic in all the schools. The choice of the head as a unit seems
sufficiently justified by the two facts that, on the one hand, in every
representation of the human body the head is always visible, and forms
a part distinct from the rest of the body, and that, admitting that
it makes the eighth part of the height, this number is particularly
convenient, not being too great; and, on the other hand, it is
divisible by two. In this respect it offers, for example, a great
advantage over that of nineteen, which represents the proportion of the
middle finger to the height.
[Illustration: FIG. 64.
THE FACIAL ANGLE OF A MONKEY.
(Camper.)]
Gerdy, who has adopted the law of eight heads, divides the height of
the body in the following way: the first division comprises the head
itself; the second extends from the chin to the level of the nipples;
the third from the nipples to the umbilicus; the fourth from the
umbilicus to the symphysis pubis; the fifth from the pubis to the
middle of the thigh; the sixth from the thigh to the knee; the seventh
from the knee to the middle of the leg; and, lastly, the eighth, from
the middle of the leg to the sole of the foot (Fig. 65).
[Illustration: FIG. 65.
OUTLINE OF THE HUMAN BODY (and proportions).]
The face itself can further be subdivided into subordinate parts. The
classical method of subdivision is to say that the head is the length
of four noses: one from the top of the head to the top of the forehead
(hair), one each for the forehead and nose, and one for the part below
the nose. This is generally, however, incorrect. It is better to divide
the face into two portions across the equators of the eyeballs; and
subdivide the lower half into two, for the greater part of the nose
above, and the lips, mouth, and chin below.
Now, if we submit to experiment the system of the law of eight heads,
we see that it is accurate only in subjects of great height--for those
who attain seventy-four inches and over; below seventy-two inches the
subjects do not measure more than seven and a half, or only seven
times the height of their head. In fact, the height of the head is a
quantity which varies very little according to the subject; it is on
the average, as an absolute measurement, from 8⅔ to 9 inches, and the
variations which this value may present do not range below 8¼ inches
or above 9 inches. A subject who measures eight heads is very tall (9
× 8 = 72, equal, or superior, to 72 inches); and a subject who only
measures seven heads is of short stature (8⅔ × 7 = 61, equal, or more
frequently exceeding, 61 inches).
This difference in the number of heads that the body measures in
relation to absolute height seems more interesting than the narrow
theory which would assign strictly the length of eight heads to each
human figure. This absolute system does not agree with that which
observation proves correct. Besides, it would be an error to suppose
that the ancient sculptors would be slaves to such a system of
proportions, since we find in their works precisely the same variations
that we do in nature. The _Gladiator_, it is true, measures eight
heads; but at the first glance at this _chef d’œuvre_ we have the
impression of a subject of great stature--of a man tall and spare. The
_Apollo_ and the _Laocoon_ measure only 7⅔, and the _Antinous_ only 7½
heads.
The variations in height are almost solely caused by the greater or
lesser length of the lower limbs. Whether the subject be tall or short,
the trunk (with the head and neck) varies comparatively little; but the
thighs and legs make the differences of length. Regarding the diversity
that we meet with in this question, we see that Gerdy himself has not
been exact in indicating the points where the lengths of the head begin
and terminate which divide the lower limb, the middle of the thigh, and
the lower part of the knee; those points are badly defined, especially
as he does not indicate precisely the superior extremity of the thigh.
But the looseness and contradiction becomes still more evident when
we come to seek, according to the various authors, the intersection
between the fourth and fifth head; that is to say, the middle of the
body. Without speaking of the singular inconsistency of Vitruvius, who
places the middle of the body at the level of the navel, we will note
only this fact, that for the passage from the fourth head to the fifth
some take the pubis, others some other point.
The centre of height falls lower as the stature of the subject
is increased. In subjects of small stature the centre of height
corresponds to the symphysis of the pubis; for those of middle height
and over, it falls about half an inch below the pubis. But it may be
situated at a still lower level, and the artists of antiquity have
frequently placed it much lower. In fact, as Professor Sappey says, the
taller the stature, the more the centre of the body tends to fall below
the symphysis, and the figures of heroes and gods are of tall stature.
We will say, then, in conclusion: 1, that the head, compared with the
height, is shorter as the height increases; 2, that to produce a human
figure, the absolute dimensions of which would give the impression of
a subject of short stature, it would be necessary to give it about 7½
heads, and to cause the centre of the body to fall on the symphysis
pubis; while to produce a figure to give the impression of tall stature
it would be necessary to give it 8 heads, and to place the centre of
the body more or less below the symphysis pubis.
=Second Part.=
MUSCLES AND MOVEMENTS.