The course and relative positions of the principal arteries and veins
of the Systemic circulation are shown in this plate. The arteries
commence from the great arterial trunk, called the aorta, and their
branches are distributed to all parts of the system. The venous
branches, which accompany the arteries, unite into two great veins,
the superior and inferior vena cava, which convey the blood back to
the heart.
_a_, The left ventricle of the heart. _b_, The right auricle. _c_,
The superior vena cava. _d_, The root of the pulmonary artery. _e,
e_, The aorta, which is seen arching backward over the heart, and
passing downward into the abdomen, where it divides into its two
great branches, the iliac arteries, through which the blood passes to
the lower extremities. _f_, The inferior vena cava, which accompanies
the descending aorta and its branches, and returns the blood from the
lower extremities. The dotted lines represent the outlines of the
kidneys.
[Illustration: full body drawing]