CHAP. I. Shews the upper or ascendent Trunk of the great Artery, with its propagations that are distributed through the Head.
THere is no controversie among writers of Anatomy concerning the number and original of the Arteries,* 1.1 but an unanimous consent, that all the propagations, which are scattered through∣out the body, take their rise from one, which they call Aorta, and that this is derived out of the Heart. But the Heart con∣sisting of two sinus or cavities, a right, and a left one; this great Artery grows out of the left sinus or ventricle [A], where it is largest, and more hard, and griestly, then elswhere. But as soon as it is grown out, and before it fall out of the Pericardium or purse of the Heart,* 1.2 it presently propagates two small sprigs [a a] one of each side, which they call Arteriae Coronariae, the Crown-Arteries, because together with the vena Coronalis, or Crown-vein, they compass the basis of the Heart in manner of a Crown, and from these many propagations are scattered downward all along the Heart. But they are more, and greater about the left, then the right ventricle, as we have also formerly said concerning the vein, because the Heart needs a greater plenty of blood on that side, as which beats with a perpetual, and more violent motion, wherein more blood is digested, then the right sinus or ventricle does: yet that propagation is bigger, and longer, which arises ont of the right side of the Artery: sometimes also there is on∣ly one, at whose orifice a little valve is found. Those propagations being thus dissemi∣nated, the Artery ascends somewhat under the Trunk of the vena Arteriosa,* 1.3 or Arterial vein, and pierces through the Pericardium, and, having got above it, is cleft [B] into two branches, which because of their natural greatness we will call Trunks, and because one ascends [C] and the other runs downward [Q] that shall be the Ascendent Trunk, this the Descendent. Yet the Descendent, and lower one is bigger by much then the upper,* 1.4 because that serves more parts, then this. For the Ascendent one goes only to some parts of the Chest, to the Head, and Arms; but the lower to very many parts of the Chest, to all the lowest belly, and the Legs. That therefore we may treat of the great Artery with more perspicuity, we will first shew the Ascendent Trunk, and its progress through the Chest, and Head, and after that its branches distributed through the Arms. Then we will fall upon the Descendent one, add explain the manner of its distribution through the Chest, and lowest belly, and lastly through the Legs.
The Ascendent therefore or upper Trunk of the Aorta [C], being fastened to the Oe so∣phagus, or Gullet, climbs upward betwixt the rough Artery, and Hollow-vein, and the mediastinum, or partition of the Chest. Which situation of it they ought diligently to observe, who desire to know the reason of that Aphorism, which is the four and twentieth of the fifth Section in Hippocrates: For sayes he, cold things, as snow, and ice, are ene∣mies to the Breast, provoke coughs, and cause eruptions of blood, and distillations. Tru∣ly they are enemies to the Breast, because, whilest they are swallowed down through the Gullet, they cool the rough Artery, that lyes next to it, together with the Gullet, which part being of it self cold does easily take harm from so violent a cold: hence the cough, and other diseases of the Brest follow one another in a long row. But issues of blood happen in like manner, the great Artery being cooled, whereby the vital Spirits, and the blood are driven back to the Heart, and from thence are sent up forcibly to the Head, which being stuft, eruptions of blood are caused by its dropping forth at the Nostrils, as