SITUS VISCERUM. 461 



1 . Medulla oblongata. upon the pars basilar. occipitis, between 

 the hemispheria cerebelli, behind pons Varolii. In its middle 

 line: 



a. Fissura long, anterior ,- on the side of this : 



b. Corp. pyramidalia. Next to these the olivary bodies, 

 and most posteriorly and externally the corp. restiformia. 



2. Pons Varolii, upon the clivus, behind the crura cerebri, be- 

 tween the crura cerebelli ad pontem. 



3. Substa-ntia perforata media, between crura cerebri. 



4. Carp, mammiUaria, aboveproc. clinoidei posterior es, between 

 crura cerebri. 



5. Tuber cinereum, between the anterior extremities of tractus 

 optici, elongating itself forwards and downwards in the infundibu- 

 lum to the hypophysis in the sella turcica. 



6. Chiasma nerv. opticorum, upon the proc. clinoidei medii, 

 {Between the two lamince cribrosce, which lie before the crura cere- 

 bri at the commencement of fosses Sylvii, and the posterior extre- 

 mity of sukus tractus olfactorius. On the sides of the base are 

 situated, 



1. Fossa Sylvii, with the insula of Reil, and the oper- 

 culum. 



2. Crura s. pedunculi cerebri, behind the tractus opticus, 

 before pons Varolii. 



3. Tractus opticus, behind lamina cribrosa, before crus 

 cerebri, winding round them. 



4. Gyrus hippocampi, externally close to crus cerebri, 

 forms in front the uncus. 



712. ' VII. Cerebral nerves. 



1. Olfactorius, appears at the internal extremity of fossa Sylvii 

 and lamina cribrosa, passes in the sukus tractus olfactorius on 

 the inferior surface of the anterior cerebral lobes, enlarges (bulbus 

 cinereus) upon the cribriform plate of the ethmoid bone, and quits 

 the cranial cavity with a double series of filaments. 



2. Opticus, appears at the anterior border of chiasma, passes 

 through foram. opticum, where it lies above and internal to art. 

 ophthalm., into the orbit, where it is situated on the outside and 

 below it. 



3. Oculo-motorius, appears on the inside of the pedunc. cerebri, 

 passes through a fissure of the dura mater, approaching proc. cli- 

 noid. post., into the sinus cavernosus, along the superior wall, out- 

 side the carotis interna ; enters the orbit th rough Jissura orbital, 

 superior. 



