HYPOGLOSSAL NERVE. 533 



muscles of the tongue and the other muscles attached to the hyoid 

 bone. 



Some sensory fibres lie in its descending branch, but these, 

 probably, are derived from the vagus or trifacial nerves, with 

 which its branches inosculate. 



It is also said to contain the vasomotor fibres of the tongue. 



Section of the nerve causes paralysis of the muscles of the 

 tongue; when this is unilateral, the tongue inclines to the injured 

 side, while being protruded from the mouth ; but while being 

 drawn in, it passes to the sound side. This is easily understood 

 when it is borne in mind that the two acts depend upon the 

 intrinsic muscles of the tongue, bringing about an elongation or 

 shortening of the organ respectively. 



