THE MAMMALIAN NERVOUS SYSTEM 103 



last described can be seen in a' careful dissection to separate 

 from them below the interventricular foramen and then to 

 turn dorsalward immediately behind the foramen. They 

 enter the stria medullaris thalami, a strong superficial fiber 

 tract passing across the rostral border of the thalamus and 

 bordering the taenia thalami. This tract is sometimes called 

 the tractus taeniae; it terminates in the habenula. 



(3) Tractus olfacto-tegmentalis. — These fibers originate with 

 those of the tractus olfacto-mamillaris, but instead of terminat- 

 ing in the mammillary body they pass on to enter the tegmentum 

 of the cerebral peduncle. They can be dissected, though they 

 are hard to separate from tractus olfacto-mamillaris. 



(4) The olfactory projection tract of Cajal passes from the lat- 

 eral olfactory area and amygdala backward into the regions of 

 the mammillary body and cerebral peduncle. We have not 

 been able to dissect these fibers, but they can be demonstrated 

 microscopically. 



(5) Stria terminalis. — This tract (also called stria or taenia 

 semicircularis) connects the medial olfactory area in the vicin- 

 ity of the anterior commissure with the amygdala under the 

 uncus, running dorsally of the internal capsule fibers at the line 

 of contact of the thalamus with the cerebral hemisphere. The 

 dissection of this tract should not be made at this time; see 

 Section 132. 



(6) Diagonal band of Broca. — This is a ridge extending trans- 

 versely across the ventral aspect of the cerebral hemisphere 

 between the area olfactoria intermedia, or tuberculum olfacto- 

 rium, and the optic chiasma (Fig. 8). It contains both cells 

 and fibers, the latter connecting the medial olfactory area 

 with the lateral olfactory area. The diagonal band and the 

 stria terminalis contain correlation fibers connecting the same 

 areas, the former running across the extreme* ventral surface of 

 the hemisphere and the latter across the extreme dorsal surface 

 of the brain stem along the line of contact of the cerebral 

 hemisphere with the thalamus. 



(7) Tractus mamillo-thalamicus (tract of Vicq d'Azyr or 

 tractus thalamo-mamillaris). This tract runs from the corpus 

 mamillare forward and dorsalward to the nucleus anterior of 

 the thalamus. It can readily be dissected by scraping off the 



\ 



