/'///; LATERAL \'I-:\T !>'!( 'LI'S 



851 



THK I.ATKIIAL VFATUK'I.KS 



Two of I lie four cavities of the ventricular system of the brain are in the 

 telrnceplialon. Form their position, one in each cerebral hemisphere, they 

 are known as the lateral ventricles. They arise as lateral dilations of the cavity 

 of the anterior of the primary vehicles, and. just as the fourth ventricle remains 

 in communicat.ion with the third by way of t lie ai|U;r<luct us cereliri, so the lateral 

 are connected with the third by the two interventricnlar foramina (Monroi). The 

 whole ventricular syMem. including the central canal of the spinal cord, is lined 



FIG. 632. A CAST OP THE Fen i< YENTRII-LKS OF THE ENCEPHALON. (After Welcker.) 



coRNV OF 



\ rr.ici.E 



/v/77.-! i:\n:iri I.M: i m; I.VK.V 



(Mu\/;ul, 

 Tlllltn VKXTKICLE 



IM I:RIOR CORXU or i,.i TI:I:.\L 

 VEMI:H I.F. 



AQUJEDUCTVS CEREBRI 

 FOURTH VENTRICLE 



POST K RIO R CORXU OF I, ATI l:M. 

 VENTRH'l.K 



by a continuous layer of ependyma and contains a small quantity of lymph known 

 as die cerebro-spinnl fl nit!. 



Kach lateral ventricle is of an irregular, horseshoe shape. It consists of a central 

 portion or body and three cornua. which correspond to the three poles of the hemi- 

 sphere. The portion projecting into the frontal lobe is known as the anterior cornu, 

 that projecting into the occipital lobe is the posterior cornu, and the portion which 

 sweeps downwards into the temporal lobe is the inferior cornu. The ventricles of dif- 



Fio. 633. DIAGRAM OF SAGITTAL SECTION THUOT-C;II I.ATKHAL PART OF RIGHT HEMISPHERE 

 SHOWING LATERAL VENTRICLE FROM THE OUTER SIDE. 



CIHIHRllIt PLEXCS 



Itri.i: OF POS- 

 TERIOR <<}i:.\r 



COR/T.v 



SJSI'Tf.M 



I'/ I I.I i IDVM 



- 



i v/'/'x v 

 CHOJtioii) ri.K.vrx nh- i. \n--i: n n; COR!fO 



CM -HATE 

 KUCLSVS 



\ IKTKK VKXTKIl I I.M; 



i m: \\u-\ 

 ''.i rn.t n: M i i.Ki'g 



I.\'TKIt\ II. IM'SI'I.K 



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ferent individuals vary considemhlv in cai>:icity. and the cavity of a given ventricle 

 is not uniform throughout. In some localities the space may IM> quite appreciable, 

 while in other places the walls may be approximate or even in apposition. Kach 

 lateral ventricle is a completely closed cavit y except at the interventricular foramen. 

 However, a strip of the floor of the inferior cornu is separated from the exterior of 

 the brain by only the thin, non-nervous lamina forming the floor of the chorioid fissure. 



