214 



THE NERVOUS SYSTEM 



corpora quadrigemina appear. It forms a marked projection, the pulvinar, 

 which overhangs the medial geniculate body and the brachia of the corpora 

 quadrigemina (Figs. 88, 154). For purposes of description it is convenient to 

 recognize four thalamic surfaces, namely, dorsal, ventral, medial, and lateral. 



The dorsal surface of the thalamus is free (Figs. 91, 154). It forms the 

 floor of the transverse fissure of the cerebrum and is separated by this fissure 

 from the parts of the cerebral hemisphere which overlie it, that is, from the 



Free portions of columns offornix. 

 Head of caudate nucleus-^ 

 Medullary strior v ""' 

 Third ventricle x N 



Eabenular trigone ^ 

 Pineal bodv - 



Superior colliculus J 



Tail of caudate nucleus- 



Super, quadrigeminal brack,- 



Infer, quadrigeminal brack. - ' 



Cerebral peduncle- ' 



Corpora quadrigemina-'' 



lateral filaments of pans--' 



Anterior medullary velum- - 



Lingula of cerebellum 



Tela chorioidea of fourth ventricle 



Corpus callosum 



/Lamina of septum pellucidum 

 /' Columns offornix 



"^ y A nterior commissure 

 ^~ Optic recess of ventricle III 

 - A nterior tubercle of thalamus 



, Terminal stria 

 ^ s Tania chorioidea 



^-- Habenular commissure 

 x'Z,awzwa affixa 

 ^ .Superior quadrigeminal 



brachium 

 ^-' Pulvinar of thalamus 



.Lateral geniculate body 



~~ -Medial geniculate body 

 ~~ Inferior colliculus 

 - Trochlear nerve 

 Brachium conjuctivum 

 , Lateral recess of fourth ventricle 

 Brachium pontis 

 .Peduncle of flocculus 



Flocculus of cerebellum 



Lateral aperture of- ventricle IV 

 ^Chorioid plexus of ventricle IV 

 \Rhomboidfossa (intermediate portion) 

 Medial aperture of ventricle IV 



Funiculus gracilis 



Medulla oblongata 

 Fig. 154. Dorsal view of the human brain stem. (Sobotta-McMurrich.) 



fornix and corpus callosum. Laterally it is bounded by a groove, which separates 

 it from the caudate nucleus and contains a strand of longitudinal fibers, the 

 stria terminalis and a vein, the vena terminalis (Figs. 154, 155). The dorsal 

 surface is separated from the medial by a sharp ridge, the tania thalami, which 

 represents the torn edge of the ependymal roof of the third ventricle. The 

 taeniae of the two sides meet in the stalk of the pineal body. The prominence 

 of this torn edge of the roof is increased by a longitudinal bundle of fibers, 



