550 BLOOD-VASCULAR SYSTEM OF THE HORSE 



(5) The superior labial artery (A. labialis superior) arises from the facial in 

 front of the facial crest (Fig. 435). It passes forward under the dilatator naris lat- 

 eralis and levator nasolabialis to the upper lij), gives twigs to the upper part of the 

 cheek and the lateral nasal region, and ramifies in the upper lip, anastomosing with 

 the opposite artery and the palato-labial. 



(6) The lateral nasal artery (A. lateralis nasi) arises usually a little above the 

 preceding one, and runs forward jiarallel with it and inider the levator nasolabialis 

 to the nostril (Fig. 435). It supplies branches to the lateral nasal region and the 

 nostril. 



The vessel is often double. It may arise from the superior laljial at the point of bifurcation 

 of the facial or with the dorsal nasal from the infraorbital artery (as in the ox). In some cases 

 it gives off a dorsal nasal branch. 



(7) The dorsal nasal artery (A. dorsalis nasi) arises on the levator laliii superi- 

 oris proprius and passes forward under the levator nasolabialis to the dorsum nasi 

 (Fig. 435). 



(8) The angular artery of the eye (A. angularis oculi) rims toward the internal 

 canthus of the eye, where it anastomoses with the orbital branch (Ramus malaris) 

 of the infraorbital artery (Fig. 435) . 



In addition to the preceding, unnamed branches are supplied to the submaxil- 

 lary salivary gland and the submaxillary lymph glands. 



3. The posterior auricular artery (A. auricularis posterior) arises at an acute 

 angle from the external carotid just above the origin of the masseteric. It passes 

 upward under cover of the parotitl gland, to which it gives branches, and divides 

 into several branches which supply the skin and muscles of the external ear (Fig. 

 435 j. The posterior branch passes to the posterior part of the base of the ear, 

 where it divides into two branches; of these, one (Ramus intermedins) passes up the 

 convex surface of the external ear to the apex, while the other (Ramus medialis) 

 winds around to the anterior (inner) border, and forms an arch with the inter- 

 mediate branch. The external branch (Ramus lateralis) passes up the posterior 

 (external) ])order of the ear and forms an arch with the intermediate branch. 

 The deep branch (A. auricularis profunda) enters the interval between the exter- 

 nal auditory canal and mastoid process, and passes through an opening into the 

 interior of the external ear and ramifies in the skin which lines it. It gives off the 

 stylomastoid artery, which passes through the stylomastoid foramen into the tym- 

 panum, forms an arch around the membrana tympani, and supplies the middle ear 

 and its muscles. 



THE SUPERFICIAL TEMPORAL ARTERY 



• This artery (A. temporalis supcrficialis) is much the smaller of the two terminal 

 branches of the external carotid. It passes upward behind th(> posterior border of 

 the ramus of the mandible under cover of the parotid gland, and divides below 

 the level of the condyle into the anterior auricular and transverse facial arteries. 

 It is crossed superficially by the facial nerve. 



The anterior auricular artery (A. auricularis anterior) passes upward behind 

 the temporo-mandibular articulation under cover of the parotid glantl, cross(>s the 

 zygomatic arch, and reaches the temporalis muscle. It is crossed deeply at its 

 origin by the superficial temporal nerve and is accompanied by a satellite vein 

 and the auriculo-])alpebral branch of the facial nerve. It is distributed to the 

 skin and the temi)oral and anterior auricular nuiscles, and sends a l)ranch through 

 the conchal cartilage to the skin which lines it. Collateral twigs are detached to 

 the parotid gland, and an anterior branch anastomoses with the supraorbital 

 artery. A branch sometimes passes into the parieto-temporal canal and anasto- ■ 



moses with the i)()st('ri()r meningeal (mastoid) artery. 



The transverse facial artery (A. transversa faciei) is larger than the preceding. 



