HEAD AND NECK OF THE HORSE 



193 



connected with one of the columns of the fornix, while its posterior 

 extremity is associated with the amygdaloid nucleus. 



The dorsal surface of the thalamus is convex in the main, with a 

 slightly more prominent elevation, the anterior tubercle, in front. The 

 surface is bounded medially by a prominent border formed by a longi- 

 tudinal ridge, white in colour, known as the medullary stria (stria 

 medullaris), the anterior end of which joins one of the columns of the 

 fornix. The posterior end of the stria is at the base of the pineal body, 

 where some fibres join the nucleus habenulse,^ while others cross to the 



Lateral ventricle. 



^Corpus callosum. 



Hippocampus. 



White matter. 



Suprapineal recess. 

 Third ventricle. 



Lateral ventricle '' 

 (inferior cornu). 



.Fimbria. 



-Thalamus. 



- Hippocampus. 



Cerebral peduncle 



iMammillarv bodv. 



Hypophysis. 



Fig. 9L — Transverse section of the brain at the level indicated by B in 

 Fig. 89 (looking forward). 



opposite nucleus in the eoiriniissura JiabenularMii. The choroid tela 

 of the third ventricle is attached along each stria medullaris, and when 

 the tela is removed an irregular tcenia - thalami is left. 



The medial surface of each thalamus is flattened, and forms one of 

 the lateral walls of the third ventricle. Crossing the ventricle and 

 uniting the two thalami is a thick, rounded gre}^ bridge of tissue, the 

 intermediate viass (massa intermedia). 



The lateral and ventral surface of the thalamus cannot be demon- 

 strated at present, since they are connected with other parts of the 

 brain. The lateral surface is in contact with the internal capsule, and 

 the ventral surface rests on the dorsal or tegmental part of the cerebral 



13 



Habenula (dim. of habena) [L.], a thong or strap, a rein. 

 Tcenia [L.], a flat band, tape, ribbon. 



