FACIAL NERVE. 697 



foramen is painful, but still more painful is that of the peripheral facial 

 branches, as will be obvious from what has been stated. 



The foregoing illustration shows accurately the course of the trunk of the 

 facial nerve and its superior, middle and inferior branches on the face, as well 

 as the points where the individual motor fibers pass into their muscles. By the 

 application of one electrode at these points, the other being applied to any in- 

 different part of the body, the individual muscles can be made to contract elec- 

 trically. The electrodes are applied in the same way in employing electricity for 

 therapeutic purposes. 



Pathological. In connection with paralysis of the facial nerve it is above all 

 important to determine whether the seat of the affection is a peripheral one, in 

 the neighborhood of the stylomastoid foramen, or in the course of the long 

 Fallopian canal, or, finally, central (cerebral). A careful analysis of the symp- 

 toms will lead to a conclusion in this respect. A frequent cause for paralysis at the 

 stylomastoid foramen is designated rheumatic and probably depends upon exuda- 

 tion paralyzing the nerve by compression (perhaps at the situation of the lymph- 

 space discovered by Rtidinger at the inner side of the Fallopian canal between 

 the periosteum and the nerve, an evagination of the arachnoid sac). Other causes 

 are inflammation of the parotid, direct traumatism, pressure of the obstetric 

 forceps in the new-born. In the course of the canal fractures of the petrous bone, 

 effusions of blood into the canal, syphilitic deposits, caries of the petrous bone, 

 principally in connection with inflammation of the middle ear, are to be mentioned 

 as causes of the paralysis. Among intracranial causes there should finally be 

 mentioned affections of the cerebral membranes and the base of the skull in the 

 vicinity of the nerve, disease of the facial nucleus, and finally of the cortical center 

 for the nerve and the connections between this and the nucleus. 



The symptoms of unilateral facial palsy are as follows: i. Paralysis of the 

 muscles of the face: the forehead is smooth, free from furrows; the palpebral 

 fissure is open (paralytic lagophthalmos) , with the external canthus at a lower 

 level. The anterior surface of the eye readily becomes dry, and the cornea appears 

 dull, chiefly because the distribution of tears is interfered with by absence of 

 winking, and, in consequence of the dryness, slight inflammatory irritation may 

 result (xerotic keratitis) . According to some observers the facial nerve is believed 

 to be the secretory nerve for the lacrimal gland (so that the secretion of tears is 

 interfered with when the nerve is paralyzed) and the vasomotor nerve for the 

 conjunctiva. Its course is believed to be as follows: facial, greater superficial 

 petrosal nerve, sphenopalatine ganglion, second division of the trigeminus, orbital 

 nerve. In order to protect the eye from exposure to light, the patient generally 

 rotates the globe upward and outward beneath the upper eyelid, and relaxes the 

 elevator of the upper eyelid, so that the lid droops somewhat. The nose cannot 

 be moved, and the nasolabial fold is obliterated. In consequence, the sense of 

 smell may be impaired, because the nasal orifice can no longer be dilated. The 

 derangement of smell, however, is due principally to the defective distribution of 

 tears (in consequence of paralysis of winking and of the muscle of Horner) , which 

 leaves the corresponding side of the nasal cavity dryer than normal. Horses, 

 which in breathing visibly dilate the nostrils, are said either to die after bilateral 

 division of the facial nerve from interference with respiration or at least to suffer 

 from marked respiratory difficulty. The entire face is drawn toward the unaf- 

 fected side, so that the nose, the mouth, and the chin generally occupy an oblique 

 position. In consequence of paralysis of the stylohyoid muscle and the posterior 

 belly of the digastric, the base of the tongue on the paralyzed side may occupy 

 a lower level, and on forced movement of the base of the tongue this organ 

 may undergo a deviation toward the unaffected side. Paralysis of the buccinator 

 interferes with the normal formation of the bolus of food, which collects in the 

 concavity of the relaxed cheeks from which the patient must eventually 

 remove it with the fingers. Saliva and fluid readily escape from the angle of the 

 mouth. In strong expiration the cheek is distended like a sail. Speech may be 

 interfered with in consequence of difficulty in forming the labial consonants 

 (particularly when the paralysis is bilateral) and also the vowels o u 6. Speech 

 becomes nasal in the presence of (bilateral) paralysis of the branches to the muscles 

 of the palate. Whistling, suckling, blowing, expectoration are interfered with. 

 Bilateral paralysis causes many of these symptoms in exaggerated degree. Others, 

 such as the oblique position of the face, naturally are wanting. The face is com- 

 pletely relaxed, without any play of expression, and the patients cry and laugh 



