TEE CBANIAL OR ENCEPHALIC NERVES. 831 



Among: these ramuscules, the superior is remarkable for its great volume ; 

 it passes beneath the zygomaticns muscle, lies close to the inferior border of 

 the dilator naris lateralis, beside the superior coronary artery, and afterwards 

 runs below that muscle, where it joins the terminal ramuscules of the superior 

 maxillary nerve, with which it is distributed to the textures of the upper lip and 

 alje of the nose (Fig. 453, 7')- 



A second ramuscule — the inferior, smaller than the preceding — follows the 

 inner aspect of the depressor labii inferioris muscle, to mix by its anterior 

 extremity with the terminal fasciculus of the inferior maxillary nerve, and 

 ramify— with the proper filaments of that fasciculus — in the tissue of the lower 

 lip. 



Between these two principal branches is a series of smaller ramifications 

 destined to the buccinator muscle. Among these are some which become 

 inflected on the inner face of the masseter, and reach the deep portion of the 

 buccinator, where they anastomose with the filaments of the buccal nerve. 

 Other ranuiscules— situated below the principal inferior branch— are expended 

 in the panniculus on the face ; one of them, after bending round the lower 

 border of the inferior maxilla, reaches the submaxillary space. 



Functions of the Facial Nerve. — This nerve excites contraction of the 

 muscles of the middle ear, external ear, the cheeks, lips, nostrils, orbicularis of 

 the eyelids, and the cervico-facial panniculus. By its great superficial petrosal 

 filament, it influences the movements of the muscles of the soft palate, and it is 

 admitted — as already noticed when speaking of the gustatory nerve — that its 

 tympano-lingual ramuscule acts on the submucous muscular layer of the tongue. 

 The facial nerve, also, without doubt, exercises its influence on the parotid 

 gland. 



It serves as a medium for the passage for vaso-motor and excito-secretory 

 filaments. 



It is to be remarked that the facial nerve has no influence over the masseter 



plexus of Soliptids. It is useful to know these differences in accounting for the phenomena 

 that accompany accidental or experimental lesions in this plexus. 



As a general rule, the facial nerve divides into two branches close to the parotid gland. 

 The auriculo-temporal nerve divides into three unequal branches when it reaches the max- 

 illary condyle ; the upper branch — slender, single, or bifurcated — follows the superficial 

 temporal artery and disappears in the skin of this region, or rejoins in part the temporo-facial 

 plexus. The other branches lie close beside the two branches of the facial nerve — the two 

 nerves being confounded with each other as they proceed to their terminations. This type, 

 ■which we consider very rare, is modified in various Witys : — 



1. The sensitive and motor filaments, instead of being confounded suddenly at the anterior 

 border of the parotid gland, may proceed side by side. This separation is generally less 

 marked in the superior temporo-facial branch ; when it exists in the inferior branch, the motor 

 filament is situated between the masseter and the panniculus, the sensitive filament between 

 the latter and the skin. 



2. Separation of the sensitive and motor portions is complete. The inferior facial branch 

 especially may proceed alone to the lips; the sensitive branch for it follows at first the 

 superior branch of the plexus, and only leaves it about the middle of the masseter, to pass on 

 the cheek and rejoin its satellite motor filament in the lower lip only. In this case, the 

 inferior branch has only filaments from the facial. 



3. Instead of a prompt separation between the branches of the temporo-auricular and the 

 facial nerve, tliere is sometimes observed fusion of the four branches, whicli may be pro- 

 longed some distance beyond the parotid gland. We have seen dispositions of this kind, in 

 which the inferior branch (tiien always mixed) was detached from the fasciculus, at the 

 level of the eye, in forming a very acute angle. 



Sometimes marked differences are observed in the two plexuses in the same animal. 



