186 THE ANATOMY OF THE HORSE. 



gives off in this part of its course are the superior and inferior labial 

 arteries ; and unnamed cutaneous or muscular branches, of which those 

 that pass to the massetcr muscle are the largest. 



The Inferior Labial Artery is the largest branch. It is given off on 

 the surface of tlie inferior maxilla. It passes beneath the depressor 

 labii inferioris, and descends to the lower lip, at the hinder edge of the 

 buccinator. At the mental foramen it anastomoses with the mental 

 branch of the inferior dental artery, and in the lip it anastomoses on 

 the mesial plane with the opposite vessel. 



The Sujjerior Labial Artery is detached opposite the zygomatic ridge. 

 It passes beneath the levator labii superioris alteque nasi and tlie lateral 

 dilator of the nostril, and reaches the upper lip, in which it anastomoses 

 with the palato-labial artery. 



The Submaxillary Vein (Plate 29) runs in close company with the 

 artery. Where the vessel appears on the face, and throughout the 

 greater part of their course, the vein is above the arteiy. It is formed 

 by an angidar and a nasal branch, the first of which begins in the lower 

 eyelid, while the other originates beneath the skin of the false nostril, 

 and passes over the levator labii superioris alaeque nasi to join the first. 

 It receives branches corresponding to those of the artery, and, in addi- 

 tion, the alveolar and buccal veins join it at the edge of the masseter. 

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

 angular and nasal brandies is conspicuous during life. 



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

 being at first between the edge of tlie 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, to open on the inner surface of the cheek, opposite the 

 third upper molar tooth. 



The Transverse 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 oft' 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 teniporo-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 7)iasseteric branch 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 



