BLOOD-VESSELS OF CEREBELLUM 



907 



The blood-vessels of the mesencephalon, in addition to the supply derived from the postero- 

 lateral group of central arteries, include the vessels of the quadrigeminate bodies and those of the 

 cerebral peduncles. The arteries of the quadrigeminate bodies are usually six in number, 

 three for each side — the superior, middle, and inferior quadrigeminate arteries. The superior 

 and middle are branches of the posterior cerebral arteries, and the inferior are branches of the 

 superior cerebellar arteries. The superior supply the superior quadrigeminate bodies and the 

 epiphysis; the middle supply both the superior and inferior quadrigeminate bodies, and the 

 inferior the inferior quadrigeminate bodies. They all anastomose in the pia on the surface of the 

 stratum zonale, forming a fine-meshed plexus, and from this superficial plexus the terminal 

 branches pass into the substance of the bodies. The veins terminate in the vein of Galen (v. 

 cerebri magna.) 



The arteries of the cerebral peduncles form two groups, mesial and lateral. The mesial 

 pedimcular arteries are branches of the basilar and the posterior cerebral arteries. They pass 

 to the medial sides of the penduncles and supply the superior and medial part of the tegmentum. 

 The vessels of this group which accompany the fibres of the oculomotor nerves are known as the 

 radicular arteries; they supply the root-fibres and the nuclei of the nerves, which receive no 

 other branches. The lateral peduncular arteries are branches of the posterior cerebral and 



Fig. 714. — Showing the Capillary Supply of the Cerebellar Cortex. (After Aby, 

 "Journal of Comparative Neurology," Vol. IX.) 



Capillaries 

 of molecu- 

 lar layer 



Line of the 



Purkinje 



cells 



Recurrent 



capillaries 



to granular 



layer 



Arteriole 



passing 



through 



cortex to 



medulla 



Recurrent 



capillaries 



to granular 



layer 



Line of the 



Purkinje 



cells 



Arteriole 



passing 



through 



cortex to 



medulla 



Recurrent 



capillary to 



granular 



layer 



Arteriole 

 passing 

 through 

 cortex to 

 medulla 



superior cerebellar arteries. They supply the lateral portions of the peduncles and the lateral 

 part of the tegmentum. The veins of the mid-brain terminate in the basilar veins and the vein 

 of Galen. 



The blood-vessels of the cerebellum. — Six arteries supply the cerebellum; two, the 

 posterior inferior cerebellar, are derived from the vertebral arteries, and the remaining lour, 

 two anterior inferior and two superior cerebellar, from the basilar artery. The course and 

 general distribution of the arteries are described in Section V, but here it must be noted that the 

 branches of these six vessels form a rich network in the pia mater on the surfaces of the cerebellar 

 lobes, and that extensions of the plexus pass with the folds of the pia mater into the sulci and 

 fissures. From the superficial plexus terminal branches pass into the interior of the cerebellum 

 and their collaterals form capillary plexuses ix^ the white and grey substance. The extensions 

 of the surface plexus are of three lengths:— (1) a longer set, which pass through the cortex of the 

 cerebellum and supply the white substance of the corpus meduUare; (2) a set of shorter arterioles 

 which pass through the molecular layer of the cortex and break up in its granular layer; (3) the 

 shortest set pass into the cortex and immediately break up in its molecular layer. The meshes 

 of the capillary plexuses in the grey susbtance are ovoidal and their axes run radially. The 

 meshes of the plexuses in the white substance are parallel with the nerve-fibres. In addition to 

 the vessels mentioned, a distinct branch is distributed to each dentate nucleus. This springs 

 either from the superior cerebellar or from the anterior inferior cerebellar artery of the corre- 

 sponding side. 



