824 



THE NKRVOUS SYSTEM 



epiphysis with the posterior commissure below it and the habenular trigone on its 

 either side. 



The thalami are two ovoid, couch- like masses of grey substance \\hich form 

 the lateral walls of the third ventricle. The cavity of the ventricle is narrow, and 

 quite frequently the thalami are continuous through it across the mid-line by a 

 small but variable neck of grey substance, the massa intermedia or middle commis- 

 sure. The upper surfaces of the thalami are free. The edges of the tela chorioidca 

 of the third ventricle are attached to the lateral part of the surface of each thalamus, 

 and, when removed, leave the ta'nia chorioidca lying in the chorioidal sulcus. Each 

 thalamus is separated laterally from the caudate nucleus of the telencephalon, by 

 a linear continuation of the white substance below, known as the stria terminalis 



FIG. 613. DORSAL SURFACE OF DlENCEPHALON WITH ADJACENT STRUCTURES. 



(After Obersteiner.) 



ANTERIOR CORNU 



OF LATERAL 



VENTRICLE 



FIFTH VENTRICLE 



SEPTUM 

 PELLUC1DUM 



COLUMNS OF 

 FORNIX 



STRIA TERMINALIS 



ANTERIOR 



COMMISSURE 



Til I II I) VENTRICLE 



MASSA INTER- 

 MEDIA (.Viilille 

 commissure) 

 CHORIOIDAL 

 SULCUS 



SUPERIOR 



COLLICULUS 



MEDIAL fi/;xir. 



ULATE BODY 



LATERAL SULCUS 



OF 

 M /;.v F.NCEPHA LON 



POXS 



STRIA ACUSTICA 



MEDIAN SULCC* \ 



TRIGONUM HYPOOLOSSI 

 RESTIFORM BODY 

 CLA VA 

 POSTERIOR FISSURE 



POSTERft-TXTERUEDIA TE 

 SULCUS 



POSTERO-LA TERAL SULCUS - 



CORPUS CALLOSUM 



NUCLEUS 

 CA I'DA TUK 



FOR A 31 EX 1XTER- 

 VENTJUCULAEE 

 (jtfbnnri) 



ANT i; i; i< >n TniER- 



fl.i: III-' THALA- 

 MUS 



STRIA 3IKDUL- 

 LAR1X THAI. AMI 



1IAKEXULAR fo3l- 

 MISSURE 



EPIPHYS1S 



XULCUS < nr.p. 



QUAD. MElllALIX 



INFERIOR 

 COLLICULUS 



FREXUL U3[ VELI 



LING UI.A 

 CEREBELJJ 



FACIAL E3IIXKXCE 



AREA ACUSTICA 



TRIGONU3I VAGI 



TUBERCULU3r CfXEA TI'M 

 FUNICULUS GRAC1LIS 

 FL'KJCULCS CUXEATUS 

 LA TERAL FUNlCrLUS 



(taenia semicircularis). Like the quadrigemina, each thalamus is covered by a thin 

 capsule of white substance, the stratum zonale. The average length of the thala- 

 mus is about 38 mm., and its width about 14 mm.; its inferior extremity is directed 

 obliquely outwards. The dorsal surface usually shows four eminences, indicating 

 the position of the so-called nuclei of the thalamus. These are the anterior nucleus 

 or anterior tubercle, the medial nucleus or tubercle, the lateral nucleus, and the pul- 

 mnar, the tubercle of the posterior extremity. The pulvinar of the human brain 

 is peculiar in the fact that it is so developed as to project inferiorly and slightly over- 

 hang the level of the quadrigeminate bodies. The projecting portion assumes 

 relations with the optic tract and the metathalamus. 



