THIRD VENTRICLE. 509 
gradually subsides as the strand, on its way to end in the corpus mammillare, 
becomes more and more sunk in the gray matter on the side of the ventricle. 
The third ventricle communicates with both of the lateral ventricles, and also 
Middle commissure Tenia thalami 
Pineal body 
| Quadrigeminal bodies 
Central lobule 
Choroid plexus” 
Foramen of Monro 
Anterior commissure 
Foliumn 
Suleus of Monro =~ — eacuminis 
We 
k Tuber 
Mesa valvule 
\ valvule 
Lamina cinerea jy 4); 
| 
PITUITARY | Nut. 
— Pyramid 
Tuber cinereum | / 
Corpus mammillare / : 
pus ma ; —~Uvula 
Aqueduct of Sylvius 
Superior medullary veluin S 
Pp ary S Wodule 
Floor of veitricle 1v/ 
Choroid plexus ventricle IV. 
Fig. 378.—MESIAL SECTION THROUGH THE CorPUS CALLOSUM, DIENCEPHALON, ETC. 
Shows the third and fourth ventricles connected by the aqueduct of Sylvius. 
with the fourth ventricle. The aqueduct of Sylvius, the narrow channel which 
tunnels the mesencephalon, brings it into communication with the fourth ventricle. 
The opening of this aqueduct is placed at the posterior part of the floor of the third 
ventricle, immediately below the posterior commissure. The foramina of Monro 
LAT EAT aE NT. Ry 
ee EE 
gS 
on 
ANTR COMMISSURE 
\ 
Re-ortic RECESS 
INFUNDIBULAR 
RECESS 
VENT... 
Fig. 379.—-Cast OF THE VENTRICLES OF THE BRAIN (from Retzius). 
R.SP. Recessus suprapinealis. A.S. Aqueduct of Sylvius. 
R.P. Recessus pinealis inferius. F.M. Foramen of Monro. 
bring it into communication with the lateral ventricles. These apertures are 
placed at the upper and fore parts of the lateral walls, and lead outwards and 
slightly upwards between the most prominent parts of the anterior pillars of the 
fornix and the anterior tubercles of the optic thalami. They are just large enough 
