BLOOD SUPPLY OF THE SPINAL CORD. 



331 



(Fig. 100). The spinal arteries give origin to two sets of branches, 

 namely, the fissural or centrifugal, and, the centripetal arteries. 

 Both sets are end-arteries and form rich longitudinal plexuses, 

 which overlap each other but do not anastomose. 



The fissural or centrifugal arteries rise, first and chiefly, 

 from the anterior spinal artery (Fig. 100). These enter the 

 anterior median fissure and, running lateralward, supply the 



Fig. 99. The arteries and veins in the spinal cord. 

 (After Morris's Anatomy.) 



Diagrammatic. 



a. Dorsal external spinal veins, b. Posterior radicular vein. c. Peripheral venous plexus. 

 d. Anterior radicular vein. e. Ventral external spinal veins, f. Anterior central vein. g. Pos- 

 terior central artery and vein. h. Posterior spinal artery, i. Peripheral arterial plexus. 

 j. Posterior radicular artery, k. Intercostal artery. 1. Spinal ramus. m. Anterior radic- 

 ular artery, n. Interior spinal vein. o. Anterior central artery, p. Anterior spinal artery. 



greater part of the gray matter. Second, a few centrifugal arteries 

 rise from the posterior spinal arteries. Running into the posterior 

 fissure, they are distributed to the posterior white columns, the 

 posterior commissure and to the nucleus dorsalis (Clarki). 



The centripetal arteries rise from both the anterior and 

 posterior spinal arteries (Fig. 100). They enter the cord at right 

 angles to the surface, and supply the white matter and the periph- 



