646 



BLOOD-VASCULAR SYSTEM OF THE HORSE 



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

 and its muscles. 



THE SUPERFICIAL TEMPORAL ARTERY 



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

 branches of the external carotid, and is usually less than an inch (ca. 2 cm.) in length. 



It passes upward behind the 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 trans- 

 verse facial arteries. It is crossed super- 

 ficially by the facial nerve. 



The anterior auricular artery (A. 

 auricularis anterior) ascends behind the 

 temporo-mandibular articulation under 

 cover of the parotid gland 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-palpe- 

 bral branch of the facial nerve. It is 

 distributed to the skin and the temporal 

 and anterior auricular muscles, and sends 

 a branch 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 some- 

 times passes into the temporal canal and 

 anastomoses with the posterior meningeal 

 artery. 



The transverse facial artery (A. 

 transversa faciei) is larger than the pre- 

 ceding. It turns around the neck of 

 the mandible and emerges from beneath 

 the parotid gland (Fig. 560). It then 

 passes forward a short distance on the 

 masseter about half an inch below the 

 zygomatic arch, and enters the muscle, 

 in which it commonly divides into two 

 chief branches. It is accompanied by a 

 vein and a branch of the superficial tem- 

 poral nerve. It supplies the masseter and the skin of this region, and anastomoses 

 with the external maxillary and posterior deep temporal arteries. 



Fig. 563. — Right Eye of Horse. 

 a, Remnants of periorbita; b, levator palpebrae 

 superioris; c, obliquus oculi inferior; d, rectus ocuii 

 inferior; e, rectus oculi lateralis: /, rectus oculi superior; 

 g, sclera; o'> cornea; h, lacrimal gland; i, frontal nerve; 

 i', trochlear nerve; k, supraorbital artery; I, branches of 

 lacrimal nerve to gland; m, lacrimal artery; n, zygo- 

 matic nerve ; o, branch of ophthalmic artery; p, branch of 

 oculomotor nerve to obliquus oculi inferior; q, maxil- 

 lary nerve; r, infraorbital nerve; s, posterior nasal 

 nerve; t, great palatine nerve; u, small palatine nerve; 

 V, internal maxillary artery; w, buccinator artery (cut); 

 X, infraorbital artery; x', malar artery; y, spheno- 

 palatine artery; z, great palatine artery; z', small 

 palatine (or staphyline) artery; 1, posterior deep 

 temporal artery; 3, stump of zygomatic arch (sawn 

 off) ; 3, stump of supraorbital process (sawn off) ; 4> fa- 

 cial crest; 5^ temporal fossa; 6, foramen orbitale; 7, 

 foramen rotundum and anterior end of alar canal; 

 5, posterior opening of alar canal. (After Ellenberger, 

 in Leisering's Atlas.) 



THE INTERNAL MAXILLARY ARTERY (Figs. 562, 563, 564) 



This artery (A. maxillaris interna) is much the larger of the two terminal 

 branches of the external carotid. It begins at the medial side of the posterior border 

 of the mandible, about two inches (ca. 5 cm.) below the articulation of the jaw, 

 and ends in the anterior part of the pterygo-palatine fossa. On account of its 



