THE NERVOUS SYSTEM 



1457 



Frontal Lobe. — The superior frontal gyrus, the axiterior two-thirds of the 

 middle frontal g>Tus, and the upper portion of the precentral gyrus are 

 supplied by cortical branches of the anterior cerebral artery. The posterior 

 third of the middle frontal g\Tus, the inferior frontal gyrus, and the lower 

 and greater part of the precentral gyrus are supplied by cortical branches 

 of the middle cerebral artery. On the orbital surface the internal orbital 

 gyrus, olfactory lobe, and gyrus rectus are supplied by the anterior cerebraJ 

 artery, whilst the remainder is supplied by the middle cerebral artery. 



Parietal Lobe. — The whole of tlus lobe is supplied by the middle cerebral 

 artery. 



Occipital Lobe. — This lobe is supplied by the posterior cerebral artery. 

 Temporal Lobe. — The superior and middle temporal gyri are supplied by 



the middle cerebral artery, and the 

 Fcxc-brain remainder is supplied by the pos- 



terior cerebral artery. 



Mesial Surface of the Cerebral 

 Hemisphere. — The anterior cerebred 

 cirtery has an extensive distribution 

 to this surface, which it supplies as 

 far back as the internal part of the 

 parieto-occipital fissure. The parts 

 behind this fissure, namely, the 

 cuneus and the parts around the 

 calcarine fissure, are supplied by 

 the posterior cerebral artery. 



The corpus callosum is supplied 

 by the anterior cerebral arteries. 



Corpus Striatum. — The nucleus 

 caudatus and nucleus lenticularis 

 are supplied, for the most part, 

 by the antero-lateral or ganglionic 

 branches of the middle cerebral 

 artery, which pass through the locus 

 perforatus anticus. According to 

 Duret they form three sets — lenti- 

 cular, lenticulo-striate, and lenti- 

 culo-optic. The lenticular (internal 

 striate) arteries supply the globus 

 pallidus (inner part) of the lenticular 

 nucleus, the internal capsule, and 

 the caudate nucleus. The lenticulo- 

 striate (external striate) arteries 

 supply the putamen (outer part) of 

 the lenticular nucleus, and the 

 external capsule. One of the lenti- 

 culo-striate arteries is larger than 

 the others, and is subject to rup- 

 ture in cases of cerebral haemor- 

 rhage. It is known as the artery of 

 cerebral hemorrhage (Charcot). Its 

 course is outwards and upwards 

 round the outer aspect of the lenticular nucleus, between it and the external 

 capsule, and then through the internal capule to the caudate nucleus. The 

 lenticulo-optic arteries supply the posterior part of the lenticular nucleus, 

 and the anterior part of the optic thalamus on its outer aspect. 



The front part of the caudate nucleus is supplied by the antero-mesial 

 branches of the anterior cerebral and anterior communicating arteries. 



The larger arteries occupy the subarachnoid space, where they divide into 

 branches which enter the pia mater. These in turn give off smaller branches, 

 which enter the cerebral substance, some of them being cortical, and others 

 medullary, in their distribution. 



92 



-Optic Vesick 



— Mid-brain 



—Hind-brain 



Heart 



Vitelline Veins 



Protovertebral 



Somites 



Medullary Tube 



Fig. 60Q. — Anterior Part of an Em- 

 bryo Chick at the End of the 

 Second Day (Dorsal View) (Kol- 

 liker). 



