THE STRUCTURE OF THF/BRATN STEM 



423 



strand of white fibres connecting the anterior parts of the two optio 

 thalami and known as the anterior commissure. The roof of the 

 third ventricle is formed entirely of epithelium, the ependyma, along 

 the upper surface of which is the layer of pia mater, the velum inter- 



Oorpus oallosui 



Lateral vcntrir 



Nucleus caudati 



Internal capsul 



Thalamu 

 Nucleus lentiformi 



Anterior commis- 

 sure 



Colliculus superior 

 Inferior brachium 



Colliculus inferior 

 4th nerv 



Trigonum lemnisci 

 5th nerve 

 Brachium con- 

 . junctivum 



Pons 



8th nerve 



Restiform body 



9th nerve 



10th nerve 



Olive 



Optic nerve 

 Ant. perforated space 

 Optic tract 



Olfactory tract 

 Trigonum olfac. 





7th nerve 



12th nerve 



FIG. 190. Right lateral aspect of brain stem, with a part of the 

 cerebrum. (J. SYMINGON.) 



positum. The roof is invaginated into the cavity by two delicate 

 vascular fringes, the choroid plexuses. At the back part of the roof is 

 attached the stalk of the pineal body, and behind this stalk, between 

 the anterior parts of the anterior corpora quadrigemina, is a small 

 space known as the trigonum habenulce, which contains a well-marked 

 collection of nerve- cells known as the ganglion habenulce. The lateral 

 walls are formed entirely by the optic thalami. The upper surface of 

 the optic thalamus looks into the lateral ventricle of the cerebral 



