A textbook of obstetrics . tricle andbeing carried thence to thelungs, which in their unex-panded condition could notcontain it, is guided acrossthe right auricle by the Eus-tachian valve, and enters theleft auricle by means of anopening in the interauricularseptum,—the foramen the left auricle theblood from the ascending cavaenters the left ventricle and isdriven thence into the aorta,by which it is conveyed pri-marily to the upper extremityof the fetus by the ascendingbranches of the arch of theaorta. Here may be seen anarrangement peculiar to fetallife, by which the blood is di-v
A textbook of obstetrics . tricle andbeing carried thence to thelungs, which in their unex-panded condition could notcontain it, is guided acrossthe right auricle by the Eus-tachian valve, and enters theleft auricle by means of anopening in the interauricularseptum,—the foramen the left auricle theblood from the ascending cavaenters the left ventricle and isdriven thence into the aorta,by which it is conveyed pri-marily to the upper extremityof the fetus by the ascendingbranches of the arch of theaorta. Here may be seen anarrangement peculiar to fetallife, by which the blood is di-verted from the unused lungsand conveyed instead to theaorta. Just beyond the pointat which these branches aregiven off there opens into theaorta a large branch from thepulmonary artery (the ductusarteriosus), which conveys theblood that enters the rightauricle, and then the rightventricle, from the descendingvena cava, only a small quan-tity of blood, sufficient fortheir nutrition, going to thelungs. Thus it will be seen. Fig. 68.—Diagram of the fetal circu-lation: (i,<i. Aorta; b, innominate artery;c, left carotid ; , Eustachian valve; q, rightauriculoventricular opening; r, vena cavaascendens ; s, liver; /, hepatic vein ; it,branches of the umbilical vein to the liver ;v, umbilical vein ; ze/, umbilical cord ; x,bladder ; r, vena cava descendens; z,ductus venosus (Flint). that the aorta conveys a mixed blood, still further devitalized from the infusion of the venous bloodfrom the head, neck, and upper extremities, to the trunk and lowerextremities. It is by this arrangement that .1 greater quantityof arterial blood is conveyed to the brain, which develops so 84 PREGNANCY. rapidly during intra-uterine life. Following the blood-curr
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Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
