THE PONS 309 



Nucleus funiculi teretis. 



Nucleus ambiguus. 



Nucleus tractus solitarii. 



Nucleus tractus spinalis nervi trigemini. 



Formatio reticularis. (Gray.) 



The Pons 



The pons is a white mass on the anterior aspect of the brain 

 stem placed between the medulla oblongata and the crura 

 cerebri. It is convex from side to side, containing mostly 

 transverse and longitudinal fibers. The transverse fibers 

 are collected into rounded bundles, to continue as the middle 

 peduncles into the white substance of the corresponding cere- 

 bellar hemispheres. The middle peduncles are commissural 

 paths consisting of axones coursing in opposite directions 

 connecting the nuclei pontis with the cerebellum; then some 

 axones pass into the opposite middle peduncle, forming un- 

 interrupted commissural systems; again, a few fibers communi- 

 cate with nuclei in the brain stem, notably the oculomotor, 

 trochlear, and abducent cranial nerves. 



The basilar surface is in relation with the basilar process 

 of the occipital and the dorsum sellre of the sphenoid. In a 

 shallow central groove (basilar groove) is lodged the basilar 

 artery. The large sensor and small motor root of the trigeminal 

 nerve pierces the prelateral portion of the pons, near its anterior 

 pontile border; the abducent nerve passes forward and upward 

 around the posterior pontile border (prepyramidal part); the 

 facial and acoustic nerves arise further external in the latter 

 border. 



The pars dorsalis pontis, or tegmental part. The dorsal 

 surface is continuous with that of the oblongatal ventricular 

 surface, and will be described under the description of the 

 rhomboid fossa or the floor of the fourth ventricle. 



THE SUMMARY OF THE GRAY MASSES IN THE PARS DORSALIS 



PONTIS 



Nucleus of abducent nerve. 

 Nucleus of facial nerve. 



