CONSIDERATIONS OF THE BRAIN OR ENCEPHALON. 49 



secretory fibers (Pawlow). The afferent or sensory fibers of the 

 vagus rise hi the jugular and nodular ganglia of the nerve (g. 

 jugulare and g. nodosurn) within and just below the jugular fora- 

 men. Within the medulla are the genetic nuclei of the efferent 

 fibers. 



11. The accessory nerve (n. accessorius) is composed of a 

 cerebral and a spinal root both of which are efferent in function 

 (Fig. 45). The cerebral root (radix cerebralis) rises within the 

 medulla and issues from the posterior lateral sulcus below the 

 level of the olive and immediately inferior to the roots of the 

 vagus (apparent origin). This is distributed entirely by way of 

 the vagus. The spinal root (radix spinalis), having taken its ap- 

 parent origin from the lateral surface of the spinal cord and 

 passed through the foramen magnum, joins the cerebral (acces- 

 sory) root near the jugular foramen. 



12. Hypoglossal Nerve. (N. hypoglossus}. The twelfth is 

 the great motor nerve to the tongue (Figs. 21 and 45). A half 

 dozen or more radicals make it up; they rise hi the medulla and 

 issue in linear series from the anterior lateral sulcus of the medulla 

 between the pyramid and the olive (apparent origin). The root 

 bundles which emerge from the same sulcus below the level of 

 the olive belong to the anterior root of the first cervical nerve. 



The student should now turn back to Table I. Study it care- 

 fully and identify all the primary and secondary divisions of the 

 brain (Figs. 14, 15, 16, 17, 18, and 28). 



