Measurements of the Thorax
Principal anthropometric points: acromial point; sternal fossa; xiphoid point; mammillary points.
Measurements.—Thoracic Circumference.—Already described among the measurements of the form.
Recording instruments are now made that are exceedingly complicated and quite costly, that register the movements of respiration; they are used in medical clinics, but would be of little practical use in our schools.
Axillary and Submammary Circumference.—Taken as above, but at different levels.
Biacromial Diameter.—This is taken by means of special calipers called a thoracimeter or pelvimeter, because it is used to obtain the big measurements of the body (thorax and pelvis). The two buttons at the ends of the branches are applied to the acromial points, while the measurer occupies a position in front of the subject to be measured.
Transverse Thoracic Diameter.—The buttons of the thoracimeter are applied on a level with the mammary papillæ, along the axillary lines (vertical lines descending from the centre of the arm-pits).
Antero-posterior Thoracic Diameter.—This is also taken at the level of the nipples: the branches are applied anteriorly on the sternum and posteriorly on the vertebral channel.
These two diameters serve to furnish the thoracic index:
Ti = (100×d (antero-posterior))/(D (transverse))
Spirometer.—The subject takes a maximum inspiration and retains his breath until he has exactly fitted his mouth to the apparatus; then he emits all his breath in a forced expiration. This causes the index to rise, and the amount may be read upon it.
Sternal Length.—From the xiphoid point to the sternal fossa.
Bimammillary Diameter.—Distance between the two nipples.
Abdomen.—It would be really difficult to take measurements of the abdomen in the school. The principal anthropometric points to remember are the umbilical point, the two antero-superior iliac points, the pubis.
The distances which it would be useful to take are the following: xipho-umbilical and umbilico-pubic distances, which give an idea of the upper development (liver) and lower development (intestines) of the abdomen, and the biacromial diameter which measures the width of the pelvis.
Fig. 150.
Limbs.—In the case of the limbs also it is by no means easy or practicable to take many measurements. Consequently it should be sufficient to indicate that there are a great number of different measurements for every different segment of the limbs.
There are two principal instruments needed for this: a large compass with adjustable branches, for the long segments, and a small compass for the short segments. With the large compass we measure the length of the upper arm and forearm, the length of the thigh and shin, the length of the foot. With the small compass we measure the total length of the hand, its width, the length of the fingers and of the digital segments, etc.
The circumference of the limbs is taken with the ordinary metallic tape.
In order to fulfil the present-day scope of pedagogic anthropology, it is sufficient to take only a few measurements (the form and the head), but it is necessary to take them with great accuracy, and above all, to verify one's personal ability as a measurer, so that everyone who wishes to try the experiment may have a reliable method of testing himself. To this end it is necessary to know how to calculate one's own special personal error.