In the effort to determine the state of the thoracic organs due regard must be given to the structure and formation of the thorax, that is to say, to the morphology. Failure to do this will cause us to overlook facts of the utmost importance and lead to conclusions that are of more or less doubtful value. On the other hand, a careful and simultaneous study of the structure, formation and functions, putting all the data in proper relation, will lead to the discovery of facts of the utmost value, facts which would otherwise be unsuspected and remain unknown.
That there are great differences in degree of development and formation of the thorax is well known. We have all seen the flat chest, the round and full chest, the narrow chest, the broad chest, etc., and we know that each has its functional significance. Each indicates something relative to the structural and functional state of the organs.
But are not our concepts as a rule relative to the conditions of the organs more or less vague and of a very general character? Do they not as a rule lack a good deal that is proof of sound understanding?.
In all individuals with chests that are more or less asymmetrical we find two types of respiratory movements, one in which the thoracic excursion appears to be normal and another in which it is distinctly less. The effect of the latter on the functional processes is not difficult to conceive. The oxygen supply will be deficient, blood cell synthesis, metabolism and general nutrition will be imperfect, and from this many other disturbances will arise. In this case we are not likely to go far wrong in our conclusions.
But in the other we are almost certain to do so. And this will be because we will allow the wide chest movements to absorb our attention to the exclusion of other and more vital facts. We will go on the assumption that things must be quite normal, otherwise such normal movements would not be taking place. And we will thus be misled.
There are two structural facts, among others, possibly, relative to the morphology of the thorax which, I am convinced, have not received the attention their importance warrants: One concerns the length of the manubrium and the other the width of the first intercostal space. That these vary in character in different individuals has been observed many times, but it is doubtful that their physiological significance is appreciated. These two conditions are invariably associated, that is, found together in the same individual.
The fact has been confirmed in many autopsies that in every instance where the manubrium was long and the first intercostal space wide the heart was found to be small as a whole or irregularly developed, one side being small and the other normal or larger than normal, and the aortic arch was abnormally high and the calibre of the vessel less than normal. And these things have been found in individuals who had what are generally assumed to normal respiratory movements. In spite of the extensive thoracic excursions they had imperfect respiratory and circulatory functions, particularly the latter. With the heart asymmetrical it is easy to see that certain conditions were created which predisposed to certain morbid states.
Irregularities in the hydraulic current of necessity always result from imperfections in the heart or blood vessels. To begin with, the pulmonary circulation is defective, being slower than normal, hence stasis; the distribution of the blood mass throughout the body is unequal; there will be anaemia in some parts and plethora in others, with biochemical disturbances and defects in the functional processes as a natural consequence. These conditions are certain to create predispositions and susceptibilities of some kind.
Concerning the heart, Brehmer in 1885 wrote as follows: “The blood nourishes the body. But if with each contraction of the heart the amount of blood, which carries the nutritive material, is less than normal the state of the general nutrition of the body will naturally not be normal. In spite of good nutriment, such an organism will be found in the same situation as a poor peasant who will be able to provide for himself only two-thirds of the amount of food necessary for good organic equilibrium. Lacking in one or other may not mean death, but unless all are present there cannot be a state of flourishing health”.
A long manubrium and a wide first intercostal space are invariably associated with a narrow or contracted chest, that is, one with a circumference that is less than one-half the stature, with relatively short clavicles and very oblique ribs.
Some years ago Freund called attention to another important morphological fact, namely, premature ossification of the first costal cartilage. The importance of this was later confirmed by Hart and Harras. What results from this is a reduction in the superior sagittal diameter and a contraction of the superior opening of the thorax, with consequent interference or inhibition of the respiratory movement in the apices of the lungs. This in turn results in imperfect ventilation, retarded circulation, habitual stasis, lowered resistance and susceptibility to invading organisms.
Next, if we will observe the respiratory movements of several persons at the same time we will note that in one the sternum will note rise in the upper-third while in another it will be seen to make quite an excursion. The degree or amplitude of movement will depend on the state of the manubrio-gladio articulation. In men the process of ossification of the interarticular cartilage of this joint takes place considerably earlier than in women. But in all cases when it has taken place movement of this joint ceases, or at least is decreased. Early ossification of the first costal cartilage is usually accompanied by a like process in this joint, and with similar consequences.
Another fact of great importance which should be noted relates to the degree of slant of the sternum. When comparing this in a number of persons it will be found to vary considerably. In one the sternum will be seen to be practically perpendicular, in another there will be a moderate degree of slant, while in a third this will be marked. These things are significant. The perpendicular sternum indicates a shortening of the inferior sagittal diameter of the thorax, a reduction in the size of the cavity in its lower third, defective development and function of the lower lobes of the lungs.
In many instances the inferior sagittal diameter has been found to be no greater than the superior. This means a flat chest, and when found abnormally wide, as is usually the case, is highly significant from every standpoint. The pulmonary vessels and bronchial tubes will be relatively longer than normal and reduced in calibre. In the second case the conditions will be found quite normal, while in the third one an be absolutely certain that the organs in the dome of the abdomen are large, assuming that the superior sagittal diameter is normal.
In the first case the respiratory and circulatory processes are very defective. The intrapulmonary pressure will be high, the hydraulic current being retarded, with habitual stasis in the lungs; the mucosa will be habitually engorged and strongly predisposed to catarrhal trouble; the heart will be asymmetrical, aplastic on the left and over-developed on the right side, the arch of the aorta will likely to high and certain to be reduced in calibre. The subcutaneous veins over the upper third of the thorax will be very much distended.
In the second case, as has been said, conditions will be found quite normal, other things being equal; while in the third the attention must be directed to the organs in the upper abdomen, liver, stomach and spleen more particularly. That these organs are abnormally large will be further shown by a bi-hypochondriac diameter that is greater than the bi-axillary (normally it is about 2 cm. less), and by a gladio-umbilical line that is greater than one-tenth of the stature.
But by what are we to judge the relative proportions? When can we say that the manubrium is too long, the first intercostal space too wide, the superior sagittal diameter too short, etc..
Many thousands of examinations and autopsies have been made and case histories studied and the data compared. After many years of most diligent study, Professor DeGiovanni and his co-workers became convinced that a chest circumstance that was equal to one- half the stature and a sternal length that was equal to one-tenth indicated a high degree of organic development and functional activity. In every case in which they found a departure from this standard they found certain functional derangements, certain predispositions and susceptibilities, according to the character of the structural defect.
I am able to affirm, after making a further study of other measurements of the chest, drawing upon the data of hundreds of cases, that the normal superior sagittal diameter of the thorax is equal to one-eleventh of the stature and the inferior 4 cm. greater; that the bi-axillary diameter is one-sixth of the stature, taking this at a point opposite the nipples; that the manubrium is normally not over 30 per cent. of the total length of the sternum, and the first intercostal space is no wider than the others.
