ANATOMY IN A NUTSHELL. 



337 



the lumbar, and from the internal iliac arteries. (2) From the anterior and 

 posterior spinal branches of the vertebral arteries. The anterior spinal arter- 

 ies are two in number; and come from the vertebrate, just before they unite 

 to make the basilar at the foramen magnum, the anterior spinals unite to make one 

 artery, the anterior median artery. This artery lies in the pia mater, which it 



PLATE CLVII. 



LEFT COMMON 

 ILIAC VEIN 



MIDDLE SACRAL ARTERY AND VEIN 



Showing the Blood Supply to the Large [ntestine. 



supplies, and extends the wholelength of the cord. It recieves branches from the 

 lateral spinal arteries, and it sends branches into thesubstance oi the spinal cord. 

 The posterior spinals are also two in number; they come from the vertebral arteries 



a, the side of the medulla (occasionally from the posterior inferior cerebellar); 

 they pass down behind the posterior nerve roots (occasionally there is another 

 branch in front of the posterior nerve roots) to the cauda equina. Each Beg- 



