691 



The Twelfth Nerve, or Hypoglossal. This is a purely motor nerve 

 supplying the muscles of the tongue. It arises from a nucleus of grey 

 matter situated dorsally close to the middle line (Fig. 419). The nerve 

 passes ventrally outwards. 



The Eleventh Nerve. Anatomically, this nerve consists of two- 

 parts the spinal and the accessory portions. The accessory portion 

 arises from the medulla, and is, in reality, a part of the tenth nerve. 

 It arises from the same nucleus as part of the tenth nerve (Fig. 419)^ 

 and supplies splanchnic fibres, which run eventually in the tenth 



Ta;nia 



Vestibular nucleus 



Ueac. fibres of vestib. 



Dorsal nucleus 



tenth 



Fascic.^olitar 

 Restiforrn body 

 Nucleus of twelfth 



Subst. gelat. 

 I lose, root of fifth 

 Subst. gelat. 



XiK-1. ambig. 



I^-uing fibres of 

 tenth 



Issuing fibres of twelfth 



R.iphc 



Thulamo-olivary tract 

 Hilus 



< )livary nucleus 

 Kxt. arouate fibres 



Pyramid 



Arcuate uucleu? 



FIG. 419. SECTION ACROSS THE MEDULLA OBLONGATA AT ABOUT THE MIDDLE OF 

 THE OLIVARY BODY. MAGNIFIED 6 DIAMETERS. (E. A. Scha'er, from " QuainV 

 Anatomy." ) 



nerve. These fibres are chiefly cardio-inhibitory and viscero -motor. 

 The spinal fibres supply two muscles the trapezius and the sterno- 

 mastoid. 



The Tenth Nerve (the Vagus, or Pneumogastric). This is. composed 

 of afferent and efferent fibres somatic and splanchnic. The afferent 

 fibres have their cell-stations in the ganglia of the trunk and root. 

 The ingoing fibres from these bifurcate after the manner of posterior 

 root fibres. The upgoing branches are short, and end around cell* 



