102 LABORATORY OUTLINE OF NEUROLOGY 



missure on the median surface of the specimen and then teasing 

 its fibers out as they pass lateralward and forward toward the 

 olfactory bulb. (The anterior commissure contains other 

 fibers besides these, some of which pass between the corpora 

 striata of the two hemispheres and others enter the stria 

 terminalis; see Sections 125 (5) and 132.) A second part of the 

 stria olfactoria intermedia, composed of more scattered fibers, 

 terminates in the region of the anterior perforated space of the 

 same side. 



124. The area olfactoria. — This area includes the terminal 

 nuclei of the olfactory tracts mentioned in the preceding section. 



The area olfactoria lateralis includes the gray matter accom- 

 panying the lateral olfactory tract, or the lateral olfactory 

 nucleus (termed by Retzius in the human embryo, lateral 

 olfactory gyrus; see Herrick ('15), Fig. 105), and the part of the 

 temporal lobe reached by the lateral olfactory tract (region of 

 the uncus) and the amygdala. Cf. Section 126 (3). 



The area olfactoria medialis includes the gyrus subcallosus 

 (pedunculus corporis callosi), area parolfactoria of Broca and 

 septum. See Herrick ('15), Fig. 52. It is reached by the medial 

 olfactory tract. 



The area olfactoria intermedia lies between the two areas last 

 mentioned and includes the anterior perforated space (in lower 

 mammals the tuberculum olf actorium) . It is reached by the 

 intermediate olfactory tract, part of these fibers first decussating 

 in the anterior commissure. 



Tracts of the third order arise from all parts of the olfactory 

 area, and these will be considered under two heads: (1) the reflex 

 tracts, and (2) the cortical tracts. 



125. Reflex olfactory tracts. — These pass from the olfactory 

 area to the brain stem centers in the amygdala, diencephalon, 

 and cerebral peduncle. Most of them can be dissected in the 

 brain of the sheep. See Herrick ('15), Fig. 106. 



(1) Tractus olfacto-mamillaris. — This is a diffuse collection 

 of fibers from the medial and intermediate olfactory areas 

 passing backward dorsally of the optic chiasma to enter the 

 corpus mamillare. It can be dissected, though with some dif- 

 ficulty on account of the scattered arrangement of its fibers. 



(2) Tr actus olfacto-habenularis. — Fibers originating with those 



