FACIAL PAEALYSIS. 201 



are really derived from the hypoglossal, and not from the facial 

 nucleus. It is also possible that the fibres for the orbicularis 

 palpebrarum and the frontalis muscle arise in the posterior part 

 of the third nerve nucleus, and join the facial fibres by way of 

 the posterior longitudinal bundle. If these statements are correct, 

 in an isolated nuclear lesion of the facial nerve, the muscles 

 thus innervated from other nuclei should escape. 



The radicular fibres of the facial nerve may be injured in the 

 pons after they have emerged from the nucleus. They form a 

 bundle which does not pass direct to its point of exit, but first 

 sweeps around the nucleus of the sixth nerve. If these fibres 

 are damaged the facial paralysis which results is complete, 

 involving all the muscles of the face. Associated with the 

 paralysis of the face may be conjugate deviation of the eyes 

 away from the lesion, and weakness of the tongue and limbs 

 on the opposite side of the body. The conjugate deviation is 

 due to damage to the sixth nucleus as it lies in the loop formed 

 by the radicular fibres of the facial nerve, and the weakness of 

 tongue and limbs is caused by implication of the adjacent 

 pyramidal tract. 



Complete facial paralysis is characteristic of infranuclear 

 lesions. It is sometimes termed radicular or peripheral. It 

 differs from the cerebral type in that the orbicularis palpebrarum 

 and the frontalis muscles are as much paralysed as the rest of 

 the face. Consequently the eye on the affected side cannot be 

 properly closed, although the associated upward movement of 

 the eyeball appears on the attempt to do so. The tears of the 

 affected eye run down the cheek, either because the weakened 

 lids fall away from the globe so that the puncta lachrymalia are 

 not kept in proper position, or because the paralysis of Homer's 

 muscle renders difficult the passage of the tears into the nasal 

 duct. In both types of facial paralysis the failure of the 

 buccinator allows food to collect between the cheek and gums, 

 and, owing to the drawing of the mouth towards the sound side, 

 the tongue may appear to deviate from the mid line when pro- 

 truded. It still, however, maintains it proper relation to the 



