DISTRIBUTION OF THE CEREBRAL ARTERIES. 415 



over the inferior parietal and the hinder part of the superior parietal lobules, and 

 downwards over the superior and the upper part of the middle temporal convolutions. 

 The posterior cerebral artery (the origin and course of which are described 

 on p. 423) gives off close to its commencement the postero-mesial central arteries^ 

 which ascend through the posterior perforated space to the inner part of the eras 

 cerebri, the optic thalamus and the wall of the third ventricle. It also furnishes 

 two or three small twigs to the crus as it passes over that body, the postero-lateral 

 group of central arteries, which arise on the outer side of the crus and supply the 

 corpora quadrigemina and the hinder part of the optic thalamus, and one or two 



Fig. 348. CORTICAL DISTRIBUTION OF THE MIDDLE CEREBRAL ARTERY (semidiagrammatic, after 



Charcot). (G. D. T.) 



Cent., antero-lateral group of central branches; 1, inferior external frontal artery; 2, ascending 

 frontal artery ; 3, ascending parietal artery ; 4, parieto-temporal artery. 



posterior choroid arteries to the velum interpositum and upper part of the choroid 

 plexus. Its cortical branches are three in number : (a) the anterior temporal is 

 distributed to the anterior part of the uncinate gyrus and its immediate vicinity ; 

 (&) the posterior temporal supplies the middle part of the uncinate, the external 

 occipi to- temporal, and the lower temporal convolutions ; and (c) the occipital, lying 

 in the calcarine fissure, supplies the occipital lobe on its inner and outer surfaces. 



(On this subject see Heubner, Centralbl. f. d. med. Wissensch., 1872, and " Die luetische 

 Erkrankung der Hirnarterien," Leipzig 1 , 1874 ; and H. Diiret, Arch, de Physiol., 1874.) 



SUBCLAVIAN ARTERIES. 



The subclavian artery is the first portion of a long trunk which forms the main 

 artery of the upper limb, and which is artificially divided for purposes of description 

 into three parts, named the subclavian, axillary, and brachial arteries. 



The subclavian artery, arising on the right side from the extremity of the 

 innominate stem, and on the left from the arch of the aorta, passes a short way up 

 into the neck, arches outwards over the pleura and lung, and rests between the 

 scalenus anticus and scalenus medius muscles on the first rib. At the outer border 

 of the first rib it ceases to be called subclavian, and is continued into the axillary 



