identification of instruments- tubular craniophore, cubic...
TRANSCRIPT
Introduction:
In order to study man particularly that of the skeletal
remains of the skull and the face, certain specialised
instruments such as Tubular Craniophore, Cubic Craniophore
and Diagraph etc. have been designed for the purpose. This
particular aspect is dealt under Craniometry, one of the
divisions of anthropometry.
Craniometry is concerned with the
technique of measurements on the
skull and face of the skeleton. It
includes measurements of different
types such as linear, angular,
depth, volume, arc, etc., and hence different types of
instruments are needed to take
different types of measurements.
Some measurements are taken
directly on the skull which is
commonly known as direct
measurements, while others are
measured on the craniograph of the skull which is commonly
known as indirect measurements. Direct measurements are
taken by placing the skull on a pad or by mounting it on a
craniophore. In case of indirect measurement tracing is done
with the help of a set of instruments
designed for the purpose.
When compared to the
landmarks used in somatometry the
cranial landmarks are well-defined
and are much easier to locate. As in
somatometry, in craniometry also it is
always necessary to have a full knowledge
about the landmarks, to locate them
accurately, and then to take the measurements correctly
following the standard techniques.
In order to take measurements, more particularly angular
measurements, the skull must be oriented on a fixed plane
which must be well defined and accepted by all workers.
Otherwise, with the variation of the plane, the measurements
will vary and hence it will not be comparable. With regard to
the planes of orientation, Juan Comas has highlighted that
one of the problems of visual comparability of the skull can be
solved in one way only and that is by making type drawing
and then comparing them directly by either placing them side
by side, or by super imposing one type drawing upon another.
Although many planes have been suggested and Krogman
has gone to the extent of describing up to 20 yet one of the
most well defined planes and is internationally accepted is
that of the Frankfurt Horizonal Plane or eye-ear plane. The
F.H.P. is based on placing the right and left porion and the
two orbitales in the same horizontal plane. It is used as a
constant plane of reference by the physical anthropologist
when he is measuring and describing skulls.
Another plane known as nasion-inion plane is used to take
a few angular measurements. When the nasion and inion are
on the same horizontal plane, it is called nasion-inion plane.
When dealing with incomplete skulls which lack one of
these points, measurements are oriented by the nasion-inion,
glabella-inion, and even occasionally the
glabella-lambda planes or lines.
A skull may be observed from
different norms or positions. They are
1.The cranium viewed from
above(norma verticalis)
2. The cranium viewed from
below(norma basalis)
3.The cranium viewed from side right
or left (norma
lateralis)
4. The cranium viewed from front
(norma frontalis)
5. The cranium viewed from behind
(norma occipitalis).
In fact, Blumenbach (1752-1840), the founder of
craniometry has classified mankind into three different types
on the basis of the form of the skull as seen from above
(norma verticalis). The three types are the Mongolians
showing square shape, the Negroes having long and laterally
compressed shape and the Caucasians with a shape
intermediate between the former two. Hence, it is from the
skull that racial identification too can be established.
A craniographic technique involves the drawing of curves
in different planes of the skull. The best curve systems are
those of Sarasin, which are based on correct orientation of
skulls and are useful in the reconstruction of skulls. It consists
of
1. Three sagittal curves
2. Three frontal curves and
3. Four horizontal curves
Identification of the
Instruments
1. Tubular Craniophore:
It consists of a long hollow metal tube which slides in and
out of another tube fixed on a heavy tripod base provided
with adjustable screws. Here, the purpose of having a long
hollow tube whereby it can slide up & down or in and out of
another metal tube is meant for adjusting the height of the
Tubular Craniophore as per the requirement. So also the
screws provided at the tripod base is meant for adjustment to
a required level. The top of the inner tube bears an
adjustable jaw-like structure i.e. the skull holder, to which the
skull is fitted at the foramen magnum. The jaws can be
moved in two directions i.e. forward and backwards as well as
from side to side.
Manipulation:
The instrument is first placed
on a leveled plane. The skull is
then mounted at the foramen
magnum on the adjustable jaw-like structure otherwise
known as the skull holder. With the help of horizontal needle
of Martin, the skull so mounted is placed in the Frankfurt
Horizontal Plane. The height of the
tubular craniophore can be conveniently
adjusted using the screw provided at the
side. Further, adjustments can be done
with the help of the adjustable screws
provided at the tripod base. Assuming
that all the required points are in the
same plane, the required angular readings are recorded using
sliding caliper to which the attachable Goniometer is fitted to
it.
Precaution:
To avoid any damage to the
skull while fitting or mounting it
to the skull holder, cotton pads
are used as a precautionary measure. The skull should be
properly oriented on the fixed Frankfurt Horizontal Plane less,
the variation of the plane will lead to inaccurate reading.
Utility:
It is used for orienting the
skull in a desirable plane with the
help of Martin’s Horizontal needle
for taking direct angular
measurements such as Metopic
Angle, Nasal Profile Angle, Facial Profile Angle etc.
2. Cubic craniophore:
As the name implies the
instrument is cubical in shape. It
consists of a metallic skeleton
cube form by 12 metal bars with
side length of 30 cm
approximately. A jaw-like
structure for holding the skull is
fixed in the centre of the cube by means of an extended arm
on one side of the height. To the jaw-like structure, the skull
to be measured or the drawings to be done is fitted at its
foramen magnum and thus the skull remains within the cube.
Manipulation:
The skull which is to be
craniographed/drawn or to be
measured is mounted on the
clamp using cotton pads. The
cotton pads so used should be
placed in such a way that the
basion point remain uncovered
so as to be able to locate while drawing the contour of the
skull. Proper adjustment is made with the help of the
adjustable screws. With the help of the sliding caliper the
skull so mounted is placed in the N.I. plane i.e. the nasion &
inion points are at an equal distance from the left side of the
metal bar. This should not disturb the Frankfurt Horizontal
Plane. The skull has to be kept on the Frankfurt Horizontal
Plane using Martin’s Horizontal
needle. Then Sarasin’s curve
system i.e. (nasion-basion
sagittal curve) is employed for
drawing the contour of the skull.
The craniophore is turned in such
a way that the skull is placed in
a norma lateralis position. The cubic craniophore is then
placed on the drawing sheet/paper & the outline of the four
arms of the cubic craniophore drawn with the help of a pencil
as close to the frame as possible. If the craniophore has been
moved the outline so drawn will enable to bring back the
craniophore to its original position.
Precaution:
The skull has to be mounted on the Frankfurt Horizontal
Plane without which the craniographic drawings including the
angle readings will not be accurate. Cotton pads have to be
adequately used to avoid any damage to the skull while
orienting it to the skull holder.
Utility:
The cubic craniophore is used at
the time of making sectional
drawing of a skull. It is used for
drawing craniograms by means of
diagraph as well as for drawing the
normas under dioptrographs or
taking their photographs. The contour so drawn can be used
for taking indirect angular measurements.
3. Diagraph:
It consists of a vertical bar bearing
two horizontal needles. The upper one
is curved and pointed. The height of
the upper curved needle can be
adjusted to the required level using
the screws provided at the vertical bar.
It can also be rotated in any direction
for convenience while drawing the craniograph. The lower one
carries a pencil holder exactly vertical in line with the point of
the curved needle.
Manipulation:
For making the sectional drawing of a skull provided it
requires not only a number of steps/procedure to be followed
but it also required other instruments such as Cubic
Craniophore, Martin’s Horizontal Needle as well along with the
Diagraph. For this the skull to be craniographed is first
mounted on the clamp of the cubic craniophore. With the help
of Martin’s Horizontal needle it is kept on the Frankfurt
Horizontal Plane. Then nasion-basion sagittal curve of
Sarasin’s Curve Systems is employed for drawing the
contours of the skull. As mentioned earlier the skull is placed
in a norma lateralis position. The cubic craniophore is then
placed on the drawing sheet/paper & the outline of the four
arms of the cubic craniophore
drawn with a pencil as close to the
frame as possible. The outline so
drawn will help in placing it back
in its original position if any
disturbance has taken placed on
the Cubic Craniophore.
The arrangement of the
diagraph is such that the tip of the
curved arm and the tip of the
pencil remain exactly in the same
vertical line. Having all set in this
position the diagraph is then
placed at right angle for drawing
the contour of the skull. When the upper arm is moved just
touching the skull the pencil makes a drawing of the same on
the paper attached to the wall of the cube that rests on the
table.
While drawing the contour of the skull, the lead should be
kept sharp enough so that it makes a clear impression on the
paper. On the important landmarks a slight pressure is
applied on the pencil tip or using another pencil it should be
marked with a cross on the curve so as to make easily
identifiable when the lines are to be join between two
important landmarks.
Precaution:
The instrument has to be first checked for any
instrumental error i.e. the pointed tip of the diagraph should
be in the same vertical line. While drawing the contours of the
skull care has to be taken that the
upper pointed tip should not exert
any pressure on the skull less it not
only leave any unwanted impression
on the skull but it also distort the
sectional drawing as well. It should
also as far as possible remain at right angle to the skull cap.
In case of apertures, the pencil should be kept higher so that
it should not spoil the paper by smudging the drawing.
Utility:
The diagraph instrument is used for drawing the contours
of the skull which is properly adjusted in Frankfurt Horizontal
Plane on the Cubic Craniophore. The contour so drawn is
utilised for taking indirect angular measurements.
Conclusion:
The instruments so designed have been meaningfully
employed to take both direct and indirect measurements.
From the recorded measurements various indices have been
worked out whereby a number of conclusions have been
drawn. From the shape and sizes of the skull a close
phylogenic relationship between man and other primates can
be established. It is through the study of Craniometry
particularly that of tracing the contour of the various skulls a
lot of information can be obtained i.e. man’s position in the
animal kingdom can be ascertained. The shape and size of the
skull of man and his near relatives, the primates- both living
and extinct- can also be obtained by Craniometry.
The correlations among the different parts of the skull can
be established through Craniometry; as such the missing
portions of a skull can be reconstructed. Moreover, a skull can
be reconstructed from the available measurements of the
skull even if it is destroyed or lost.