368 SPECIAL ANATOMY. 



dullary stripe between corp. striatum and thalamus ; above 

 which is situated the lamina cornea, that is, a thickening of 

 the internal membrane of the ventricle (with the vena striatd). 



b. Cornu anterius. It extends from the lateral chamber before 

 the clavate extremity of corpus striatum, forwards, downwards, 

 and outwards, into the anterior lobe of the brain. The anterior 

 cornu is bounded before by the genu of corp. callosum, internally 

 by septum pellucidum. 



c. Cornu posterius s. cavitas digitata passes from the posterior 

 extremity of the lateral chamber into the posterior lobes of the 

 brain, is externally convex, behind pointed, very insignificant, is 

 situated near the basis, and presents on its inferior wall a gray 

 projection [Hippocampus minor], which depends upon a convo- 

 lution on the base of the brain, and is covered by white medullary 

 strise which give to it a digitate appearance (pes hippocampi mi- 

 nor), and pass on to blend with thefornix. 



d. Cornu descendens s. inferius, extends in an arched form from 

 the posterior extremity of cella lateralis, around the optic thalamus 

 and cms cerebri, forwards and downwards into the middle cere- 

 bral lobe. Its superior concave wall is placed close upon the in- 

 ferior convex, which forms the 



Pes hippocampi major, cornu Ammonis. This is a cylindrical 

 enlargement, thicker before and curved within, on the internal 

 concave border of which a narrow thick edging, tcenia (s. Jimbria), 

 and under that a gray, notched stripe, fascia dentata, is found. 

 The external surface consists of whiter, the internal of gray, spiral, 

 convoluted substance ; the white passes on to the corpus callosum- 

 andforniz; the gray depends upon a convolution at the basis of 

 the brain. (Compare pes hippoc. minor.) 



2. The middle cerebral ventricle, ventriculus tertius, a narrow 

 fissure in the middle line, above and behind broader, near the basis 

 of the cerebrum, lying between the two optic thalami which form 

 its lateral walls, and are covered with gray matter. Its floor is 

 curved downwards; its posterior portion, white and strong, in- 

 clined forwards, corresponds to the space between the crura cerebri ; 

 its funnel-shaped centre, to the corpp. mammillaria and infundi- 

 bulum ; its anterior portion extends as far as to the posterior bor- 

 der of the chiasma. 



Anterior wall, formed by crura anter.fornicis, before this com- 

 missura anterior and lamina terminalis, presents the foram. 

 Monroi. The posterior wall, formed by coi'pp. quadrigem., com,- 

 missur a posterior, presents under this the aditus ad aquceductu m 

 Sylvii. The roof is formed byfornix and lyra. 



