446 



ANATOMICAL TUCHNOhOGT. 



'tfihaUn. 



tunately, it is reversed as compared witli Fig. Ill and PI. II, Fig. 4. The ceplialie part 

 of the iialvula is represented much too thick. 



§ 1136. Preliminary Inspection of the Mesal 

 Aspect. — Before entering into details, the student 

 should compare the mesal series of ccelise in Fig. 116 

 with the same in Fig. Ill, and recognize the following 

 parts of their parietes by name, even although their 

 appearance may be quite unlike : cerebellum, valvula, 

 opticus, conarium, postcommissura, praecommis- 

 sura, chiasma, Tuber cinereum. 



The lateral coelise, proexlia and rldnocaiia, do not 

 appear, and the porta itself is not visible, but its posi- 

 tion coincides nearly with that of the little eminence 

 called crista, just cephalad of the medicommissure. 



§ 1137. Surfaces exposed by Semisedion of the 

 Brain. — Four different kinds of surface appear upon 

 the mesal aspect of the hemiencephalon, and they 

 should be recognized and distinguished before the 

 details are examined : — 



(1) Dorsad of the callosum the hemisphere is nat- 

 ural or free and covered by pia. 



(3) The several ccelise are lined by endyraa, which 

 likewise form a natural surface. 



(3) The commissures and other parts which extend 

 across the meson have been divided and the resulting 



surfaces are cut or artificial. With the callosum, praecommissura and postcommissura, 

 chiasma, ental portion of cerebellum, etc., the parts are white in color and fibrous in 

 texture (alba), but the medicommissure, terma, octal layer of cerebellum, etc. , are cellu- 

 lar and formed by cinerea. 



(4) Caudo-ventrad of the cephalic part of the callosum is a triangular area which is 

 naturally attached by connective tissue to the corresponding surface of the other hemien- 

 cephalon. This is the Area septalis. In man the surfaces are free, forming the lateral 

 boundaries of the pseudo-coelia. 



% 1138. Segqiental Arrangement of the Names of the Principal Parts of the 

 Cat's Brain. — The Table upon pages 48 and 49 is intended to enable the student to learn 

 more readily the large number of names according to their respective segments, and to 

 see at a glance the relations which the parts bear to each other. 



In each case, excepting perhaps the caudal portion of the prosencephalon, the part first 

 mentioned constitutes the principal mass of the segment. 



The indenting of a name signifies that the part is a subdivision of the part named 

 above ; for example, the striatwn is a division of the hemisphere, and itself includes the 

 Cauda striati. 



In most cases the apposition of names in different columns signifies that the parts are 

 in some way correlated ; e. g., under epencephalon, the arbor vitm is a surface exposed upon 

 hemisection of the cerebellum, and the pons is the great cerebellar commissure. Where 

 the parts are not correlated, the vertical line between the columns is reinforced by a short 

 vertical line ; e. g., between carina and ripa. 



In the column headed superjkies are also included the names of elevations, depressions, 

 recesses, sulci, and even cavities. 



