86 THE NERVOUS SYSTEM 



via the lingual nerve and the subm axillary ganglion, to their 

 distribution. 



It is now possible to study the effects of intra-cranial lesions 

 of the fibres which constitute the facial nerve. 



SUPRA-NUCLEAR LESIONS may be cortical or subcortical in 

 origin. In these cases there is usually some additional par- 

 alysis either of the upper limb muscles or of the muscles 

 supplied by the hypoglossal (p. 106). Owing to bilateral 

 representation in the cerebral cortex, the muscles, though 

 much weakened, are not completely paralysed. This applies 

 more especially to the muscles of the upper part of the face. 

 The orbicularis oculi, to outward appearances, is functioning 

 normally, but ^ when the patient endeavours to close the eye 

 against resistance, the presence of weakness on the affected 

 side is at once determined. 



The mouth is drawn over to the sound side as in the case 

 of peripheral lesions, but, in the expression of emotions, the 

 two sides of the face become symmetrical, since it is in such 

 movements that the muscles around the mouth are most 

 commonly associated. 



Since the lesion affects the upper neurones, the electrical 

 reactions of the muscles paralysed are unaffected. 



The sensation of taste is not interfered with, and there is no 

 disturbance of the salivary or lacrimal secretions. The stapedius, 

 being bilaterally represented in the cortex, is not paralysed. 



NUCLEAR LESIONS rarely occur alone and are almost always 

 associated with bulbar paralysis (p. 108). An intra-pontine 

 haemorrhage may affect either the nucleus or the intra-pontine 

 part of the nerve. In this case, the sixth nucleus (or its 

 emerging fibres) and the pyramidal tract are also involved 

 (Fig. 42). In the resulting paralysis, the sixth and seventh 

 nerves are paralysed on the side of the lesion, but the limbs 

 are paralysed on the opposite side. This crossed paralysis 

 is known as the " Millard-Gubler syndrome " and the position 

 of the lesion can be definitely located to the pons. The con- 



