THE VAGUS NERVE 101 



condition, which is termed bulbar paralysis. Reference is 

 made to this condition on page 108. 



INFRA-NUCLEAR LESIONS, when bilateral as in post- 

 diphtheritic neuritis, result in complete paralysis of the 

 muscles supplied by the vagi. The constrictors of the 

 pharynx and the muscles of the soft palate are affected, 

 causing difficulty in swallowing and in pronunciation (p. 108). 

 The ary-epiglottic muscles (p. 332) may be involved, and, 

 if so, there is grave danger of inspiration pneumonia. 

 Owing to paralysis of the cardiac inhibitory nerves, the rate 

 of the heart's action becomes greatly accelerated. The effects 

 on the lungs, oesophagus and stomach are not easily determin- 

 able, but they would appear to be relatively of little importance. 



UNILATERAL LESIONS may affect the vagus in its course 

 from the medulla oblongata to the jugular foramen, and they 

 are usually caused by inflammatory conditions of the dura 

 mater. The glosso-pharyngeal, the accessory and, probably, 

 the hypoglossal nerves will be affected at the same time (Fig. 

 51), but the direct results of this extensive paralysis are not 

 so serious as might be expected, because a good degree of 

 compensation is obtained, owing to overaction of the lingual, 

 palatal, pharyngeal and laryngeal muscles of the sound side. 



The vagus nerve may be affected alone below the level 

 of the greater cornu of the hyoid bone. If the lesion occurs 

 above the point of origin of the recurrent (laryngeal) nerve, 

 the symptoms are precisely the same as are found in lesions 

 of that nerve (p. 338). When the vagus is involved below the 

 origin of the recurrent nerve, no characteristic symptoms are 

 produced. 



The Accessory or Eleventh Cerebral Nerve is purely 

 motor in function. It consists of a cerebral and a spinal 

 portion, but the two are only related intimately as they pass 

 through the jugular foramen. 



The cerebral portion arises from the lower part of the nucleus 

 ambiguus (p. 94), and its fibres emerge from the medulla 



