THE STRUCTURE OF THE BRAIN STEM 379 



the fourth ventricle, the Sylvian iter, and the back part of the third ventricl* 

 From below upwards these groups of cells give origin to the fibres of : 



(a) The hypoglossal nerve. 



(b) The sixth nerve. 



(c) The fourth nerve. 



(d) The third or oculo-motor nerve. 



(2) Splanchnic Sensory Nuclei. Immediately outside the column of 

 motor cells is a column of grey matter which receives the terminations of 



FIG. 192. Diagram showing the brain connections of the vagus, glosso-pharyngeal 

 auditory, facial, abducent, and trigeminal nerves. (CUNNINGHAM after OBER- 



STEINER.) 



the afferent fibres belonging to the ninth, tenth, and eleventh nerves, and 

 is sometimes called the vago-glossopharyngeal-accessory nucleus. This grey 

 matter of course does not give rise to the fibres of these nerves, which, lik- 

 other sensory nerves, are axons of ganglion- cells lying outside the central 

 nervous system. 



(3) Splanchnic Motor Nuclei. These lie more deeply at some dis 

 from the middle line, and include the nucleus ambiguus for the efferent i 

 of the vago-glossopharyngeal, the nucleus of the seventh or facial nerve 



