626 



THE BRAIN. 



matter ; the mouth of the flask is, on each side, directed toward the median, 

 line ; the fibres pass chiefly to the superior peduncle. 



FIG. 144. 



Outline of Horizontal Section of Brain, to show the Internal Capsule. Natural size. The sec- 

 tion is taken at a level more ventral than shown in Fig. 138. The gray matter of the cortex and 

 claustrum is left unshaded, but that of the corpus striatum and optic thalamus is shaded ; OT, 

 optic thalamus, showing the median, lateral, and anterior nuclei ; NL, nucleus lenticularis, show- 

 ing the putamen large, and the inner division of the globus pallidus very small; NC, nucleus 

 caudatus, the large head in front of, and the diminishing tail behind, the thalamus ; G, the knee 

 of the internal capsule. From "Eye" to " Dig," marks the position of the pyramidal tract as a 

 whole, and the several letters indicate broadly the relative positions of the several constituents 

 of the tract, named according to the movements with which they are concerned : thus Eye, move- 

 ments of the eyes ; Hd, of the head ; Tg, of the tongue ; mth, of the mouth ; Shi, of the shoulder; 

 Elh, of the elbow ; Dig, of the hand ; Abd, of the abdomen ; Hip, of the hip ; Kn, of the knee ; 

 Dig, of the foot ; S, the temporo-occipital tract ; oc, fibres to the occipital lobe ; op, optic radiation. 

 At this level the fibres of the frontal tract, in the fore limb of the capsule in front of the pyram- 

 idal tract, run almost horizontally, parallel with the plane of the section. (Cf. Fig. 146, Fron). cc, 

 the rostrum of the corpus callosum, Spl, the splenium of the same, both cut across horizontally. 

 The thick dark line indicates the boundary of the cavities of the anterior and descending horns 

 of the lateral ventricle and of the third ventricle, the two ventricles being laid open into one by 

 the removal of the velum and ehoroid plexus, etc. The oval outline in the fore part of this cavity 

 indicates the fornix. Lateral to the nucleus lenticularis is seen in outline the claustrum, the cor- 

 tex of the island of Reil and the operculum or convolution overlapping the island of Reil. P is 

 inserted to show which is the hind part of the section. 



