ATTITIIDE AND POSITION OF THE FCETIIS.
By attitude of the foetus we understand the relations of the different parts of the foetus to each other and to the uterus. Enclosed in a cavity of limited extent, the foetus is so placed as to occupy the least possible space. It is, as it were, folded upon itself. The trunk is flexed, the chin touches the sternum, the upper limbs are crossed upon the chest, the lower ones crossed and folded upon themselves, so that the thighs are flexed upon the pelvis, the legs flexed upon the thighs, and the heels applied to the buttocks. In the free space between the upper and lower limbs the cord is placed. The entire foetus is in the attitude of flexion, and forms an ovoid, the large end of which is formed by the pelvic ex tremity, and the smaller by the cephalic end.
This attitude is in large measure due to the pressure of the walls of the uterine cavity upon the foetus; but we cannot admit, with Martel and Pinard, that the flexed attitude is due to causes solely material and extrin sic. Without accepting the theory of instinctive reason on the part of the foetus (Dubois), or the action of vital causes (Simpson), we must not forget that flexion is one of the first phenomena of embryonal develop ment. From the very first day the embryo tends to incurvation. This primal curvature seems to continue to the end of pregnancy, and is, we think, largely responsible for the attitude of the foetus in the uterine cavity. (Fig. 174.) - — The cephalic extremity is usually lowest in the uterus, and in preg nancies that go to full term. The head is usually the presenting part, though this is not so frequently the case in premature births. Ac coucheurs have sought to explain this fact by various theories. The most ancient is that of Hippocrates, which supposed that the foetus was originally head uppermost in the uterus, where it was held by bands proceeding from the umbilicus. At the end of the seventh month, the legal time of labor, these bands broke, and the foetus, from its own weight, turned a somersault, and so placed itself head downward. At
the moment of delivery the child emerged by its own efforts, its feet being braced against the fundus uteri. Hence the difficulty of delivering dead infants.
Aristotle insisted upon the correctness of this theory, and showed that the part of the body above the umbilicus is more voluminous than that below it; hence the head must tend to fall towards the uterine orifice.
Realdus Colombus recognized three presentations : 1st, and most fre quently, by the head; 2d, by the pelvic extremity ; 3d, and least common, by the trunk.
Jean Fernel adopted the theory of Hippocrates, and believed that the fcetus tore the membranes with its hands and feet.
Ambroise Pare claimed that the fcetus instinctively placed itself head downward, since delivery is most easy in that position.
Lamotto, Smellie, Solayres de Renhac, and, especially, Baudelocque, combated the somersault theory and finally overthrew it.
Baudelocque showed by autopsies that the head could occupy the in ferior segment of the uterus before the seventh month. Then, calling attention to the minuteness of the fcetus during the first months, as com pared with the size of the uterus and the amount of the liquor amnii, and its necessary mobility, to the anterior flexion of the fcetus, and to the weight of the cephalic extremity in. comparison with the rest of the body, he claimed that it was impossible to believe that the fcetus remained motionless for months at a time in the inferior segment of the womb. The uterus at term forms an ovoid, the larger end of which is upper most. The head fits itself into the lower and more pointed extremity, the buttocks and legs lie in the larger end, and the fcetus has assumed its normal position. The somersault, he claimed, could not take place at the seventh month, since the length of the fcetus is greater than the diameter of the uterus.
Bichat called attention to the agility ancl mobility of the fcetus, and to its suspension by the cord. He admits that it is not until it is to a certain extent developed that it is definitely fixed head downward.