463 
ON THE SEVENTH PAIR OF NERVES. 
over it* There are various parotideal branches which lose them¬ 
selves in the upper part of the parotid gland, and the integument 
over it. And now, the main trunk of the eighth nerve, joined 
by a branch from the posterior maxillary nerve, emerges from 
the parotid gland, turns round the cervix of the jaw, and appears 
upon the outside of the temporal artery. This is the place where 
it has usually been divided for experiments on it as the motor 
nerve of the face. The beating of the artery will always guide 
vou to it. It now becomes the proper facial nerve. Its branches 
reach to every part of the face, from the forehead to the extremity 
of the muzzle; while some of them, taking a descending as well 
as posterior course, unite with the cerebro-visceral, the spinal 
accessory, the great organic, and the first and second cervical 
nerves. 
Difference of Distribution .—There is a considerable difference in 
the distribution of the facial branches in different animals, and that 
depending upon the variety of the motions of the lips,or the power¬ 
ful action of the muscles of the jaw and neck. Observe in the 
horse the profuse distribution of the nerve about the nostrils and the 
muzzle, accounting for the beautiful play of the nostril in the 
blood-horse, and the varied action of his lips and muzzle—the 
principal seat of the sense of touch in him. Next observe the 
far fewer branches in the dog, whose lips and the alee of whose 
nostrils have comparatively little motion, and the plexus of 
ramifications going to the muscles of the jaw and even of the 
neck, which are concerned in the various and powerful action of 
the jaws, and the motions of the head generally, and of the neck. 
Again, observe the multiplicity of fibrils directed to the ear of 
the horse, compared with the same part of other animals, 
illustrating the varied play and the speaking action of the ear 
in this noble animal. 
The Function of the Nerve .—I know that the seventh is the 
voluntary motor nerve of the face—of that there can be no doubt. 
The motions of the head—the action of almost every part of the 
face—the expression of the countenance, depend partly or 
entirely on the influence of the seventh nerve; and all the 
muscles of the face, the head, and the external part of the neck, 
are perfectly under the command of the will. A great many of 
the muscles of the face, however,are connected with the discharge 
of the organic functions—voluntarily, so far as mastication is 
concerned—voluntarily in many an occasional act connected 
with respiration, as coughing, sneezing, sighing, talking: but 
involuntarily and unconsciously in the common process of breath¬ 
ing ; and involuntarily and violently, yet consciously, in the deep 
and rapid breathing of exercise or disease. 
