84 THE CEREBRUM. 



wind under the thalamus and disappear at the corresponding 

 geniculate body. The lateral root contains all the retinal fibers, 

 the medial root has nothing to do with vision. The fibers of the 

 lateral root (radix lateralis] may be traced to the lateral geniculate 

 body (80 per cent., Von Monokow), to the pulvinar of the thalamus 

 (nearly all the 20 per cent, remaining), and the rest to the superior 

 quadrigeminal colliculus. The optic radiation of the capsule con- 

 nects these centers with the medial occipital cortex. The medial 

 root rises and ends in the medial geniculate body and thalamus. 

 Its fibers form the commissura inferior (Guddeni). 



Tuber Cinereum. The posterior border of the optic chiasma 

 is continuous with the tuber cinereum (Figs. 21 and 26). Here 

 the gray matter is thickened and centrally prominent. The 

 bulbous infundibulum projects downward from it to rest in the 

 sella Turcica, where it forms the posterior lobe of the hypophysis. 

 The upper end of the infundibulum is hollow (funnel-like). Its 

 cavity forms the lowest part of the third ventricle. In man the 

 bulb of the infundibulum is solid at maturity, though hollow in 

 the embryo. It is composed largely of fibrous tissue, notwith- 

 standing the fact that it is developed from the floor of the telen- 

 cephalon. From the base (superior end) of the infundibulum, 

 the tuber cinereum extends in continuity with the anterior per- 

 forated substance on each side of it; and, behind, the corpora 

 mammillaria mark the boundary between it and the posterior 

 perforated substance of the mid-brain. 



The lamina cinerea and tuber cinereum form the inferior gray 

 commissure of the fore-brain. 



The hypophysis (pituitary body, Fig. 21) is composed of two 

 lobes bound together by connective tissue. A sheet of dura mater 

 (diaphragma settee} holds them in the hypophyseal fossa. The 

 anterior lobe, the larger, is derived from the epithelium of the 

 mouth cavity; and, in structure, resembles the thyroid gland. Its 

 closed vesicles, lined with columnar epithelium (in part ciliated), 

 contains a viscid jelly-like material (pituita), which suggested the 

 old name for the body. The anterior lobe is hollowed out on 

 its posterior surface (kidney-shape) and receives the posterior 

 lobe, the infundibulum, into the concavity. The hypophysis 



