206 



HITCHCOCK'S ANATOMY 



Highly Magnified Portion of the Middle Coat of 

 the Arteries. 



Fig.^209. lation of the blood, 



^^.^s— The inner one is smooth 

 and of a serous charac- 

 ter, for the ready pas- 

 sage of the blood over 

 it. The arteries (all 

 above ^\ tn mcn m 

 diameter) are nourished 

 by a capillary net- work 

 which is made from ad- 

 joining blood-vessels. Nerves are distributed to some arteries, 

 but ordinarily they only accompany them. 



371. The Aorta. — The arteries sent to every portion of 

 the body from the left ventricle proceed from one trunk, 

 called the Aorta, meaning a starting-point. It is nearly an 

 inch in diameter, and ascends in a perpendicular direction 

 for about two inches, when it makes a curve upon itself, and 

 descends through the thorax and abdomen until it reaches 

 the fourth lumbar vertebra, when, as is the case with most 

 of the large arteries, it divides into two branches of equal 

 size. Between the curve or arch of the aorta and the heart 

 no branches are given off, but from the summit of this arch 

 to the subdivision in the abdomen a great number of branches 

 are distributed to the different portions of the chest and ab- 

 domen. 



372. Description of Particular Arteries — Innominata 

 — Carotid — Subclavian — Axi llary — Brachial — Ulnar Ra- 

 dial — Palmar Arch. — The first branch arising from the sum- 

 mit of the aortic arch is the large one called the Innomi- 

 nata, or nameless artery. Next comes the Carotid, and both 

 distribute themselves to the head and upper extremities. 



371. What is the Aorta? What does the word aorta mean? Give its course till it 

 subdivides. Where does it divide into the common iliacs? 372. Where are the In 

 nominate Arteries ? The Carotid ? 



