220 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 



In all the measurements of the heart and other portions of 

 the vascular system, we shall speak only of the healthy or nor- 

 mal measurements at the different stages of life. 



Below the renal arteries, \1\ lines. In women 16 lines. 



Near its bifurcation, 17 " do. 15 " 



The diameter of the aorta is greater, as will be seen by these 

 measurements, both in the male and female, near the origin of 

 the innominata, than at its connexion with the heart. It is less 

 near the left subclavian, diminishes considerably near the 

 coeliac and renal branches, and from thence to its termination, 

 scarcely varies at all. These results also disprove the assertion 

 of Richerand, that the descending aorta and iliac arteries,* are 

 larger in woman than in man. In woman, the internal iliacs 

 continue to increase in size even after the age at which the 

 function of reproduction has ceased. In fact, the whole aortic 

 trunk, like the heart, continues to increase gradually in size in 

 both sexes, up to the most advanced period of life, and like the 

 heart also, as it increases in calibre, has the thickness of its walls 

 likewise augmented.! 



The branches of the aorta both in regard to size and age, 

 undergo corresponding changes with the aorta itself. Of the 

 abdominal branches, the superior mesenteric is the largest of 

 all ; the next in size are the renal and coeliac ; the two latter 

 being nearly of the same size. Hence, each kidney receives 

 as much arterial blood as the liver, spleen, and stomach togeth- 

 er. This would seem to be rendered appropriate by the relative 

 functions of the organs ; that of the kidneys being to depu- 

 rate the mass of blood of its saline and many other noxious 

 principles. 



Of all the organs in the body, the heart and arteries are the 

 only ones which constantly increase in dimensions; in old 

 age the muscles become atrophied, the skin shrivels, and even 

 the skeleton diminishes in bulk. 



* See (further on) measurement of iliac. 

 \ See Richerand's Physiology, 10th edit. 



