Pedagogical Anthropology - Maria Montessori (best free novels TXT) 📗
- Author: Maria Montessori
- Performer: -
Book online «Pedagogical Anthropology - Maria Montessori (best free novels TXT) 📗». Author Maria Montessori
Plagiocephaly is extremely common; if very apparent, it constitutes a grave defect, but not if only slight. For that matter, it would be difficult to find a cranium rigorously symmetrical, even among normal persons.
3. Crania with curved and symmetrical lines, but in which the perimeter consists not of a single ellipsoidal curve, but of two curves.
a. Clinocephalic Cranium.—The coronal suture has a girdle-like furrow, in such fashion that there result an anterior and a posterior curve which together form a sort of figure 8. This anomaly may be perceived also from the lateral norm.
b. Cymbocephalic Cranium.—- There is a girdle-like furrow along the sagittal line, so that the cranium has the appearance of being divided into two pockets, one on the right hand and the other on the left.
B. Lateral Norm.—The observer must stand at the side of the subject to be observed and look at him perpendicularly to the profile.
We remain standing while we look if the subject is an adult and is standing up, but we sit down if the subject is a child and is standing; and we determine the vertical position by moving the subject's head as the occasion requires.
I note, as seen from this norm, two anomalies in which the ellipsoidal uniformity outlining the profile of the cranium is altered.
a. Oxycephalic Cranium.—The line of the profile is noticeably raised at the bregma, from which the anterior part of the cranium continues to rise, almost in the direction of the forehead, instead of curving backward. In its entirety this anomalous cranium has the form of a "sugar loaf."
b. Acrocephalic Cranium.—The line of the profile, on the contrary, is not raised until near the lambda.
C. Occipital Norm.—The observer places himself behind the subject and gazes perpendicularly at the occipital point.
D. Frontal Norm.—The observer stands in front of the subject and gazes at him on a level with the forehead.
I may point out only one very important anomaly seen from this norm.
a. Scaphocephalic Cranium.—The lateral parts of the cranium are flattened to such a degree that the vault is extremely narrow along the sagittal line (see Figs. 51 and 52).
Craniometry.—The volume of the cranium is of high importance because it bears a relation to that of the brain. In the studies which have been made relative to the correspondence between physical and intellectual development, the measurement of the cranial volume comes first in order.
In measuring the cranium it is necessary to use:
a. the millimetric tape measure, b. the craniometric calipers, c. the compass with sliding branches, d. the double square. In order to facilitate the task of measuring and to secure uniformity it is necessary first to locate the craniometric points to which it will be necessary to apply the instrument. These craniometric points are easily located on the cranium, where a great number of them have been studied. In the case of a living person, on the contrary, these points are reduced to a small number because of the difficulty of accurately locating them.
The points on the vault of the cranium, along the sagittal line, are:
The nasion (point of union of the nasal and frontal bones). The ophryon (middle point of the line tangent to the two superciliary arches, a line corresponding to the horizontal drawn transversely across the forehead and passing through the two points on the temporal lines which are nearest to the median line. This point lies in an important region of the forehead, situated between the two eyebrows—the glabella. The central point of the middle region of the forehead above the glabella is called the metopion). The bregma (point of juncture between the coronal and sagittal suture). The vertex. The lambda (point of juncture between the sagittal suture and the occipital or lambdoid suture). The occipital point. The inion (situated at a level midway between the occipital point and the occipital foramen).Laterally we have these other craniometric points:
The external orbital apophysis (formed from the frontal bone). The supra-auricular point. The auricular point (corresponding to a little depression which may be felt just below the tragus and in correspondence with the zygomatic arches). The minimum frontal point (a bony angle which may be felt about 1 centimetre above the external orbital apophysis, along the temporal line).On a living person the following points can easily be located:
Along the sagittal line:
The nasion. The ophryon. The vertex. The occipital point.Laterally:
The external orbital apophysis. The supra-auricular point. The auricular point. The minimum frontal point.Now, with these points as guides it becomes practical to measure the various curves and diameters of the cranium. The curves are measured by means of the millimetric tape; the diameters by means of the calipers.
There are various curves; we shall confine ourselves to considering only the following:
The maximum circumference, which is obtained by passing the tape across the ophryon, the occipital points and the supra-auricular points, beginning to apply it at the ophryon. Its measure varies from 520 to 540 mm. in man and from 490 to 510 mm. in woman, if taken from the skull. In the case of a living person 20 mm. should be added.
If we find a circumference greater than normal, we are beginning to enter upon the anomaly which goes by the name of macrocephaly. If, on the other hand, the maximum circumference is notably smaller, we are entering upon the anomaly of microcephaly.
Measurement of Diameters.—Maximum Antero-posterior Diameter.—With the left hand place one branch of the calipers upon the glabella; the other extreme point is to be sought tentatively along a vertical line dividing the occiput in two halves. Partially close the calipers by means of the screw and then make trial by raising and lowering the posterior branch. It ought to move with a slight friction.
This is the classic diameter which measures the maximum length of the cranium and which, as we have seen, it is customary to compare with the width in order to obtain the cephalic index. In the adult man it normally oscillates between 170 and 180 mm.
Comments (0)