ARTERIES OF THE PELVIS AND HAM. 293 



The Middle Sacral Artery. 



It proceeds over the last lumbar vertebrag and down the 

 middle of the sacrum to the os coccygis ; it sends off lateral 

 branches, which are spent upon the rectum and contiguous 

 parts, and inosculate with the arteriae sacrae laterales. 



Of the Arteries which originate at and below the Great 

 Bifurcation of the Aorta. 



The Primitive lliacs, 



The terminal branches of the aorta, form an acute angle 

 with each other at their origin. They proceed downwards 

 behind the peritoneum, very near the margin of the pelvis, 

 without sending off any branch of importance. At the junction 

 of the sacrum with the ossa ilia, they divide into two great 

 branches: the Internal Iliac, or Hypogastric, which descends 

 into the pelvis ; and the External Iliac, which passes under the 

 crural arch to the lower extremity. 



— Both of these vessels are crossed by the ureters just at their 

 point of division. The right is also crossed by the intestinum 

 ileum, where it is about to pass into the colon ; the left lies 

 behind the sigmoid flexure of the colon. — 



Arteries of the Pelvis and Ham, (from Bell.) See Plate X. 

 facing page 293. 



A. The body of the last Lumbar Vertebra sawn through. 



B. The Sacrum. 



c. Ischiatic Ligaments. 



D. The Lumbar Muscles. 



E. The Great Gluteus Muscle. 



F. The Lesser Gluteus Muscle. 



G. The Gracilis Muscle. 



H. The Vastus Externus Muscle. 

 I. The Outer Hamstring Muscle ; i. e. the Biceps. 



K. The Inner Hamstring Muscles ; i. e. the Semi-tendinosus and Semi- 

 membranosus. 

 L. L. The Triceps. 



M. The Outer Condyle of the thigh bone. 

 25* 



