346 NERyOUS SYSTEM. 



The fasciculus cuneatus {c) passes laterad on account of the 

 width of the fourth ventricle and appears to end at the area 

 ovalis (/), but it may be seen passing beneath the area ovalis, 

 emerging at its cranial border and turning dorsad to enter the 

 cerebellum. It forms the side walls of a part of the shallow 

 fourth ventricle. 



The lateral funiculi are divided by longitudinal furrows into 

 three divisions. The dorsal one of these is the fasciculus 

 cuneatus lateralis or column of Rolando (Fig. 141,^). It 

 accompanies the fasciculus cuneatus into the cerebellum. 



The entire mass formed by the fasciculus gracilis, the 

 fasciculus cuneatus medialis, and fasciculus cuneatus lateralis is 

 known as the corpus restiforme, and since its fibres pass into 

 the cerebellum it is sometimes known as the pedunculus cere- 

 belli (or crus cerebelli ad meduUam). 



The following cranial nerves arise from the medulla oblon- 

 gata (Fig. 138). 



The twelfth nerve {XII) (N. hypoglossus) arises by ten or 

 fifteen rootlets from the ventral surface of the medulla oblon- 

 gata in the anterior lateral fissure (r) opposite the caudal por- 

 tion of the area elliptica (;/). 



The eleventh cranial nerve (AY) (N. accessorius) arises by 

 numerous rootlets from the lateral surface of the medulla 

 oblongata and of the spinal cord as far caudad as the sixth or 

 seventh cervical nerve. These rootlets join to form a nerve 

 which enters the cranium through the foramen magnum and is 

 closely associated at its point of exit with the glossopharyngeal 

 {IX) and vagus (A^) nerves. The line of origin on the medulla 

 passes between the dorsal ,and ventral roots of the cervical 

 nerves and is along the middle of the lateral white funiculi. 



The tenth cranial nerve {X) (N. vagus) arises by about 

 eighteen very delicate rootlets from the surface of the area 

 ovalis. The rootlets are divided into a dorsal and a ventral 

 series. The dorsal series (about twelve) arise in the groove 

 which separates the fasciculus cuneatus medialis from the 

 fasciculus cuneatus lateralis. The ventral series arise somehat 

 ventrad of this groove. These rootlets are to be distinguished 

 from those of the ninth nerve by their smaller size. 



