388 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



called the clam. On the 



Fig. 270. View, from below, of the 

 connection of the principal nerves 

 with the brain: I', the right olfactory 

 tract; II, the left optic nerve; II', the 

 right optic tract (the left tract is seen 

 passing back into * and e, the internal 

 and external corpora geniculata); 

 III, the left oculomotor nerve; IV, the 

 trochlear; V, V, the large roots of the 

 trifacial nerves; -f- +, the lesser roots 

 (the + of the right side is placed on 

 the Gasserian ganglion); i, the oph- 

 thalmic; 2, the superior maxillary; 

 and 3, the inferior maxillary divi- 

 sions; VI, the left abducens nerve; 

 VII, VIII, the facial and auditory 

 nerves; IX-XI, the glossopharyngeal, 

 pneumogastric, and spinal accessory 

 nerves; XII, the right hypoglossal 

 nerve; Q, the left suboccipital or first 

 cervical nerve (Nancrede). 



dorsal aspect of the 

 open medulla is 

 found the restiform 

 body, which passes in- 

 to the inferior pedun- 

 cle of the cerebellum 

 and represents fiber 

 tracts, the most im- 

 portant being the di- 

 rect cerebellar tract. 

 The lower half of the 

 fourth ventricle is V- 

 shaped and its apex 

 is called the calamus 

 scriptorius, from its 

 resemblance to a pen. 

 In its floor three tri- 

 angular areas are 

 found, called trigo- 

 num vagi, trigonum 

 hypoglossi, and area 

 acusticcE. It is in 

 these areas that we 

 find, respectively, the 

 origin of the tenth, 

 twelfth, and eighth 

 cranial nerves. The 

 stria acusticce are 

 transverse ridges in 

 the floor of this ventri- 

 cle, extending across 

 its middle part from 

 the median sulcus to 



