OF THE VESSELS IN GENERAL. 241 



twigs. Thus the aorta bifurcates and forms the primitive iliacs, 

 these latter bifurcate also in their turn; the primitive carotids 

 are also divided into two smaller branches. The intestinal 

 vessels present this dichotomic division in a remarkable man- 

 ner. 



The angles that the vessels form in dividing, and at which 

 the branches are separated from the main trunks, vary, but 

 the greater number are acute towards their smaller branches. 

 We should observe with Haller, that these angles, to which 

 much importance was formerly attached, are mostly destroyed 

 or changed by dissection, and by removing the cellular tissue 

 which surrounds the vessels. Some of the angles are nearly 

 right angles; these are generally the first and the largest divi- 

 sions of the trunks: for instance, the branches of the curvature 

 of the aorta, the coeliac, the renal arteries, &c. ; the renal and 

 hepatic veins, the sub-clavian veins, the jugulars, &c.; the 

 thoracic duct at its entrance into the left sub-clavian vein, and 

 some others, such as the median artery (sacra media) &c. 

 Some vessels form even obtuse angles, such are the first inter- 

 costal vessels, the inferior vessels of the cerebellum, those of 

 the heart,* and some vessels of the limbs, &c. The greater 

 number finally form acute angles, and often very acute, such 

 are, for instance, the spermatic vessels. 



We must observe with respect to the angles, which are con- 

 sidered as being right angles, and even-obtuse, that the greater 

 number are really acute; but at a small distance from the ori- 

 gin, the branches after a little distance change their direction, 

 bending their course in contrary direction from that of the 

 trunk, resembling very much the bent of the limbs of the 

 weeping willow. 



No law or general rule can be deduced from the observation 

 of the angles formed by the divisions of the vessels. Thus 

 we observe the bifurcations or divisions, and sub-divisions of 

 the vessels of every size, to form angles more or less acute. 



What is true of the large vessels, is equally so of the smallest, 



* The coronary vessels might, with propriety, have been enumerated first 

 among those which form an obtuse angle, with the main trunk from which 

 they arise. TBANS. 



