182 THE ANATOMY OP THE HORSE. 



In thin-skinned, fine-bred animals the course of the vein and of its 

 angular and nasal branches is conspicuous during life. 



Stenson's Duct (Plate -29), or the parotid duct, crosses the face, 

 being at first between the edge of the masseter and the vein. It then 

 passes forwards and upwards beneath the artery and vein, on the surface 

 of the buccinator ; and finally it perforates that muscle under cover of 

 the zygomaticus, and opens on the inner surface of the cheek, opposite 

 the third upper molar tooth. 



The Teansverse Facial Artery (Plate 29) is a branch of the 

 superficial temporal. Given off beneath the surface of the parotid 

 gland, it turns round the edge of the ramus beneath the condyle, and 

 at the anterior border of the gland it gives off a large masseteric branch. 

 Having gained the face, it descends for a few inches on the surface 

 of the masseter muscle, immediately below the zygomatic arch ; and then, 

 about midway between the temporo-maxillary joint and the orbit, it 

 penetrates the masseter, and is distributed to it. Where the vessel is 

 on the surface of the muscle, it is covered only by the thin facial 

 panniculus and the skin, and is conveniently placed for the taking of 

 the pulse. Its masseteric hi-anch at once plunges into the substance of 

 the masseter, where it anastomoses with the maxillo-muscular artery, 

 and with the posterior deep temporal by a small branch which traverses 

 the corono-condyloid notch. 



The Maxillo-Muscular Artery (Plate 29) is a collateral branch of 

 the external carotid. Beneath the parotid gland it bifurcates to form 

 a pterygoid and a masseteric hranch. The former passes within the 

 ramus to reach the internal pterygoid muscle. The latter emerges 

 between the ramus and the parotid gland, above the insertion of the 

 stylo-maxillaris, and penetrates the masseter. 



Veins. — The transverse facial and maxillo-muscular veins accom- 

 pany the arteries of the same name. The former joins the anterior 

 auricular to foi-m the superficial temporal vein, the latter empties itself 

 into the jugular. 



The 7th Nerve on the face (Plate 29). This nerve appears on the 

 face a little below the articulation of the jaw, where it emerges from 

 beneath the parotid gland. Before its emergence it is joined by the 

 subzygomatic branch of the inferior maxillary division of the 5th. The 

 nerve divides into a variable number of branches, which anastomose on 

 the surface of the masseter and form a plexus, termed in man the j^es 

 anserinus (from its resemblance to the foot of a goose). In this plexus 

 it is not possible to distinguish, among the motor fibres proper to the 

 nerve itself, those sensory fibres derived from the subzygomatic nerve. 

 This plexus is covered by the skin and the thin facial panniculus, both 

 of which receive branches from it. Below the inferior edge of the 

 masseter, branches of the plexus are continued over the submaxillary 



