356 . NERVOUS SYSTEM. 
surface of the tuber cinereum. It bears at its ventral end the 
hypophysis (pituitary body) (Fig. 138, ¢), a vascular non-ner- 
vous body of unknown function. The hypophysis is lodged in 
the sella turcica of the sphenoid bone. 
At its caudal border the tuber cinereum bears two white 
elevations, the mammillary bodies (corpora mammillaria) 
(Fig. 142, g). 
The third ventricle (Fig. 143, 4; Fig. 141, v) is a very 
narrow slit-like space, of considerable extent dorsoventrally, 
but less than a millimeter in width; it lies between the medial 
Fic. 143.—-LONGITUDINAL MEDIAN SECTION OF BRAIN. 
2, olfactory bulb; 7/, cerebrum; ///, section of cerebellum, showing ‘arbor 
vite’’; /V, medulla oblongata. a, tractus olfactorius; 4, substantia perforata an- 
terior; ¢, anterior commissure; ¢@, lamina terminalis; ¢, optic chiasma; 7, massa in- 
termedia of thalamus; ¢’, infundibulum; ¢, hypophysis; 4, third ventricle; 2, mammil- 
lary body; 7, aqueductus cerebri (or aqueduct of Sylvius); 4, pons; 2, velum medul- 
lare anterius; 7, fourth ventricle; ~, velum medullare posterius; 9, continuation of 
canal of spinal cord; #, corpus callosum (body); g, genu of corpu callosum; 7, ros- 
trum; », splenium; ¢, septum pellucidum; z, fornix; v, pillars of fornix; w, choroid 
plexus of third ventricle; x, stria medullaris; y, corpus pineale; z, cranial corpus 
quadrigeminum; 2’, posterior commissure. 1, sulcus falcialis; 2, sulcus cruciatus; 
3, sulcus splenialis; 4, sulcus marginalis; 5, sulcus supracallosalis (or callosalis). 
ends of the thalami (Fig. 141), and extends ventrad into the 
tuber cinereum, and thence into the infundibulum (Fig. 143, 
g’). Dorsad it extends into the corpus pineale (Fig. 143, 7). 
The third ventricle communicates caudally near its dorsal 
border with the aqueductus cerebri (7); craniclaterally with 
the lateral ventricles, through the interventricular foramen 
