The Seventh or Facial Nerve.
—This nerve has sometimes to be stretched for spasmodic affections. When the desire is simply to reach its trunk it may be sought through an incision behind the ear, by which the posterior border of the parotid is exposed, the sternocleidal insertion identified, the nerve lying in the interval between these two landmarks. A more easy method of reaching it would probably be by an incision in front of the ear just before its main branch divides as it enters the parotid gland. If necessary this may be followed backward until the main trunk is reached.
Fig. 401
Intracranial exsection of Gasserian ganglion; dura open, brain lifted up. Hartley-Krause method. (Marion.)
Fig. 402
Relations of the facial and spinal accessory nerves: a, carotid; b, int. jug.; c, facial nerve; d, transv. proc. atlas; e, spinal acces.; f, stern. mast. muscle. (Marion.)
Neuro-anastomosis for Facial Palsy.
—In view of the hopelessness of facial paralysis, when resulting from destructive injuries to the nerve trunk, the introduction of anastomotic methods has marked a very distinct advance. Ballance, in 1895, was the first to apply neuro-anastomotic methods to the facial nerve. He attached the facial to the spinal accessory. His own experience, as well as that of half-a-dozen later operators, proved that nerve regeneration is possible, but that in this particular instance voluntary movements of the face were often accompanied by distressing and unsightly associated movements of the shoulder, and vice versa. Hence, Taylor and others suggested the use of the hypoglossal instead of the spinal accessory, the former being a purely motor nerve running near the facial, intimately associated with it in function, and arising by nuclei, which are equally closely associated in the cranial centres. The operation is indicated in all cases of paralysis caused by lesion of the nucleus within the brain, or the nerve trunk at the base of the brain, or along its course. It is justifiable in Bell’s palsy, when there is complete reaction of degeneration in the facial nerve after several months of treatment ([Fig. 402]).