THE VESSELS. 311 



cess : anastomosing with art. occipitalis and cervical, profunda ; a larger 

 branch. 



Art. meningea posterior enters through foram. magnum to the falx cere- 

 belli. 



In the cranial cavity : 



c. Art. spinalis posterior, arises at the sides of medull. oblong, and divides 

 into an ascending branch for the walls of the fourth cerebral ventricle, 

 and a descending which passes down on the posterior surface of the spinal 

 marrow, becomes enlarged by the rami spinales passing into it, and is thus 

 continued as far as the inferior extremity of the vertebral column. It 

 gives an anterior and posterior branch for the posterior roots of the nn. 

 spinales. 



d. Art. spinales anterior, larger than the former, arises close under the art. 

 basilaris, associates with that of the other side, passes in a groove on the 

 anterior surface of the spinal cord, as art. mediana, as far downwards as 

 the os coccyx, continued by branches of cervical, ascendens, vertebralis, in- 

 tercostales and lumbales. 



e. Art. cerebelli inferior posterior, arises on the outer wall of vertebral., 

 curves round before the roots of the vagus and hypoglossus, backwards 

 round the medulla oblong., passes forwards between the central and lateral 

 lobes of the cerebellum, and divides into an internal and external branch, 

 the last of which ramifies on the inferior surface of the cerebellum, and 

 anastomoses with art. cerebelli. 



555- Art. s. truncus basilaris, the continuation of the two Artt. 

 vertebrates, commences in the sulcus between medull. oblong, and 

 Pons Varolii,, and terminates on the anterior border of the last. 

 Its inferior wall rests upon the clivus ; its superior wall gives nu- 

 merous branches to the Pons Varolii ; from the lateral walls 

 arise : 



f. Art. cerebelli inferior anterior arises in the middle of art. basilar., passes 

 outwards under nerv.facialis and acusticus to lobul. anterior cerebelli. 



1. Auditiva interna passes off from it, or the basilaris itself, and goes 

 with nerv. acusticus to the cochlea and vestibule. 



g. Art. cerebelli superior arises close to the anterior extremity of art. basila- 

 ris, behind n. oculo -motor ius, turns round pedunculus cerebri upon the 

 superior surface of Pons Varolii, and supplies, divided into an external 

 and an internal branch, the borders and superior surface of the cerebellum. 



h. Artt. cerebri posteriores s. profunda, the two terminal branches of basilaris, 

 pass forwards, diverging, bend backwards upon the superior [inferior] 

 surface of pedunculi cerebri to the inferior of the posterior lobes of the 

 brain ; give, quite at the commencement, numerous branches to the sub- 

 slant, perforata grisea between the crura of the brain ; receive ramus com- 

 municans, which passes off from Carotis interna, and thus completes 

 the 



