362 



ANATOMY OF THE CENTEAL NERVOUS SYSTEil. 



ansa leniiformis, etc. In proportion to its enormous mass, the thalamus sends 

 only a few filers downward. 



The tracts arising from the ganglia run, for the greater part, in two, 

 white, transverse lamina, passing through their mass: the lamina medullaris 

 externa and interna. The thalamic fibers extend farther downward only to a 

 very limited extent. Essentially but a single bundle, the superior fillet, corn- 



Fig. 169. — (From the dog.) Frontal section which passes approximately 

 through the anterior third of the thalamus. Like the following sections, it re- 

 quires only a few words by way of supplementarj' explanation, since all the parts 

 are lettered. To the right and above, the fibers from the mantle pass down into 

 the internal capsule, lateral to the corpus striatum. They there meet with the 

 large fiber-system from the nucleus caudatus, penetrate it, and converge, in part, 

 as the corona radiata into the lateral thalamic ganglion. Most of the fibers, how- 

 ever, remain in the position named, and pass backward. This part must be 

 surrounded by the fiber-system of the corpus striatum, when the same passes 

 inward to its terminal in the ganglia of the interbrain. To the tracts thus em- 

 bracing the fibers there are added — close to the base — the tracts from the puta- 

 men, which form with those the ansa lentiformis. Mesial to the bundle of the 

 ansa, already met with here, lies the slender radiation passing from the olfactory 

 field to the corpus mamillare. From the olfactory radiation there is given off 

 at this level, and farther posteriorly, the bundle of the taenia thalami, which 

 ascends dorsally. This is seen to pass as far as the surface of the thalamus and 

 then to turn backward to the ganglion habenulse. The bundle of Vicq d'Azyr 

 probably belongs to the olfactory apparatus also; it develops from the medullary 

 capsule of the anterior thalamic nucleus, which is here cut in the section. 

 Paserung d. Stammgangl., Fiber-system of the corpus striatum. Riechbdl Zw. 

 E., Olfactory bundle, interbrain. StabTcranz cms Cortex, Corona radiata from 

 cortex. Stablcranx z. N. lat.. Corona radiata to nucleus lateralis. 



