100 LABORATORY OUTLINE OF NEUROLOGY 



120. Association tracts of the human brain. — In the human 

 brain tease away the tissues on the dorsal and lateral walls of 

 the hemisphere and dissect out: 



(1) short association fibers 



(2) fasciculus longitudinalis superior 



(3) fasciculus occipito-frontalis inferior 



(4) fasciculus uncinatus 



(5) fasciculus transversus occipitalis 



(6) fasciculus longitudinalis inferior 



(7) the cingulum 



These represent a few only of the more clearly defined asso- 

 ciation bundles, of which the white matter of the hemispheres 

 is largely made up. While making these dissections note 

 the relations of the fibers of the corpus callosum and of the corona 

 radiata. In well-preserved brains these tracts can be dissected 

 out with great completeness (see Section 141). Even in poorly 

 preserved brains some of them can usually be demonstrated. 

 See: Barker ('01), Chap. LXVII, pp. 1058-1069; Cunningham 

 ('15), Figs. 577, 578, pp. 649, 650; Curran ('09); Howell ('15), 

 Fig. 83, p. 185; Morris ('14), Figs. 701, 702, p. 891; Quain ('09), 

 Fig. 323, p. 359; Toldt ('04), Figs. 1230, 1231; Villiger ('12), 

 Figs. 124-127, p. 134. 



121. Rhinencephalon. — The entire olfactory part of the brain 

 is called the rhinencephalon. This apparatus is so much more 

 highly developed in the sheep than in man that the dissection 

 is much more readily carried out upon this brain. Before 

 undertaking the following dissection look up in the reference 

 books the structure of the olfactory epithelium, nerve and bulb. 

 See Cunningham ('15), p. 623; Herrick ('15), Chap. XV; 

 Howell ('15), pp. 299-305; Villiger ('12), Fig. 116, p. 118. 

 On the nervus terminalis see Section 47 (d). 



The peripheral olfactory neurones arise from cells lying in 

 the mucous membrane of the nose. These fibers terminate in 

 the olfactory bulb, which is the primary olfactory center of the 

 brain. Here lie the neurones of the second order (mitral cells), 

 whose axones constitute the olfactory tracts, or stria, terminat- 

 ing in secondary olfactory centers in the basal parts of the 

 cerebral hemisphere. 



These secondary centers in the aggregate are called the area 



