730 



DISSECTION OF THE BRAIN. 



nucleus in 

 floor of 

 fourth 

 ventricle. 



oblongata by five or six filaments close below the facial nerve, in the! 

 groove between the olivary and restiform bodies. 



Deep origin. Directed backwards through the medulla oblongata, the fibres 

 join a main nucleus beneath the inferior fovea in the floor of the fourth 

 ventricle. A considerable bundle of fibres passes to the fasciculus solitarius 

 in the medulla and upper part of the cord, and some motor fibres spring, 

 with others of the vagus, from the nucleus ambiguus in the medulla. 



Tenth nerve The TENTH, VAGUS Or PNEUMO-GASTRIC NERVE ( 8 ) issues by a 



below ninth niimber o f filaments (twelve to fifteen) from the medulla oblongata 

 in a line with, and below the glosso-pharyngeal. 



Deep origin. Taking a similar course in the medulla oblongata to the root 

 of the ninth nerve, the fibres of the vagus reach their main nucleus beneath the 

 calamus scriptorius of the fourth ventricle. Other fibres pass to the fasci 

 culus solitarius, and others spring from the small nucleus ambiguus in the 

 medulla. 



nucleus 

 beneath 

 fourth 

 ventricle. 



Eleventh 

 nerve in two 

 pieces ; 



accessory 

 from 

 medulla 

 oblongata, 



spinal from 

 cord. 



Both from 

 one mu'leus. 



The ELEVENTH or SPINAL ACCESSORY NERVE consists of two part 

 accessory to the vagus, and spinal. 



The accessory or bulbar part is of small size, and is formed by th 

 union of slender filaments continuing the line of the glosso-pharyn 

 geal and vagus nerves along the medulla oblongata, as low as th 

 first cervical nerve. After communicating with the spinal part ii 

 the jugular foramen, it passes into the vagus nerve outside the skull 



The spinal part is firm and round, like the third or the sixtl 

 nerve, but only a small piece of it can now be seen. It arises by- 

 number of fine filaments from the lateral column of the spinal con 

 as low as the sixth cervical nerve. As the nerve ascends along th 

 side of the cord it lies between the ligamentum denticulatum am 

 the posterior roots of the spinal nerves, with the upper of which i 

 may be connected. It enters the skull by the foramen magnum. 



Deep origin. The fibres of both accessory and spinal parts have bee 

 traced inwards to an elongated column of cells reaching from the lower thin 

 of the olivary body to the level of the fifth cervical nerve, and situate, in th 

 spinal part of its extent, in the outer part of the anterior horn of the gre 

 matter, and, in the medulla oblongata, behind and to the outer side of th 

 hypoglossal nucleus. 



The ninth, tenth, and eleventh nerves converge below the crus 

 cerebelli, and rest on the flocculus. From that spot they are directed 

 outwards to the jugular foramen. 



THE TWELFTH or HYPOGLOSSAL NERVE ( 9 ) appears on the front 

 of the medulla oblongata, where it is attached by a series of 

 filaments (ten to fifteen) along the groove between the pyramid 

 and the olivary body, in a line with the anterior roots of the spinal 

 nerves. The filaments of origin unite into two bundles, which pierce 

 the dura mater separately, and unite at the outer part of the anterior 

 condylar foramen. 



nucleus near Deep origin. The roots of the nerve can be followed through the medulla 

 and t fourth al oblon ata to a nucleus, which is placed in front of the central canal below, 

 ventricle. an< ^ extends upwards into the lower part of the fasciculus teres in the fourth 

 ventricle. 



Twelfth 

 nerve from 

 front of 

 medulla 

 oblongata : 



