NEUROLOGY 





chiasma, the tuber cinereum and infundibulum, and the corpora mammillaria. 

 Behind the last, the floor is formed by the interpeduncular fossa and the tegmen ;a 

 of the cerebral peduncles. The ventricle is prolonged downward as a funnel- 

 shaped recess, the recessus infundibuli, into the infundibulum, and to the apex of 

 the latter the hypophysis is attached. 



The anterior boundary is constituted below by the lamina terminalis, a thin layer 

 of gray substance stretching from the upper surface of the optic chiasma to the 

 rostrum of the corpus callosum; above by the columns of the fornix and the anterior 

 commissure. At the junction of the floor and anterior wall, immediately above 

 the optic chiasma, the ventricle presents a small angular recess or diverticulum, 

 the optic recess. Between the columns of the fornix, and above the anterior 

 commissure, is a second recess termed the vulva. At the junction of the roof and 

 anterior wall of the ventricle, and situated between the thalami behind and the 

 columns of the fornix in front, is the interventricular foramen (foramen of Monro) 

 through which the third communicates with the lateral ventricles. 



Lateral 

 ventricle 



Tda chorioidea 

 Internal cerebral veins 

 Epithelial lining of ventricle 



Epithelial lining 



of ventricle 

 Terminal vein 

 Choroid plexus of 

 lateral ventricle 



Choroid plexuses of third ventricle 

 \ Third ventricle 



Fio. 723. Coronal section of lateral and third ventricles. (Diagrammatic.) 



The posterior boundary is constituted by the pineal body, the posterior commissure 

 and the cerebral aqueduct. A small recess, the recessus pinealis, projects into the 

 stalk of the pineal body, while in front of and above the pineal body is a second 

 recess, the recessus suprapinealis, consisting of a diverticulum of the epithelium 

 which forms the ventricular roof. 



Each lateral wall consists of an upper portion formed by the medial surface of 

 the anterior two-thirds of the thalamus, and a lower consisting of an upward 

 continuation of the gray substance of the ventricular floor. These two parts 

 correspond to the alar and basal laminae respectively of the lateral wall of the 

 fore-brain vesicle and are separated from each other by a furrow, the sulcus of 

 Monro, which extends from the interventricular foramen to the cerebral aqueduct 

 (pages 741 and 742). The lateral wall is limited above by the tsenia thalami. The 

 columns of the fornix curve downward in front of the interventricular foramen, and 

 then run in the lateral walls of the ventricle, w 7 here, at first, they form distinct 

 prominences, but subsequently are lost to sight. The lateral walls are joined to 

 each other across the cavity of the ventricle by a band of gray matter, the massa 

 intermedia (page 809). 



Interpeduncular Fossa (Fig. 724) . This is a somewhat lozenge-shaped area of the 

 base of the brain, limited in front by the optic chiasma, behind by the antero- 

 superior surface of the pons, antero-laterally by the converging optic tracts, 



