590 



THE VEINS 



(c) The ophthalmic vein (\'. ophthalmica) is a short trunk, connected in front 

 with the vena reflexa and behind with the cavernous sinus through the foramen 

 laccrum orbitalo. It receives veins which correspond to the arterial branches. 



The buccinator vein (V. buccinatoria) extends backward from the external 

 maxillary along the lower border of the depressor labii inferioris and buccinator 

 under cover of the masseter, passes between the ramus of the mandible and the 

 tuber maxillare and is continued as the internal maxillary vein. It has a large 

 fusiform dilatation and is valveless. It receives a large common labial vein from 

 the labial plexus, and is usually connected with the masseteric vein. 



Fig. 463. — Deeper Vessels and Nerves of Head of Horse. 

 The parotid gland, most of the masseter muscle, and a portion of the ramus of the mandible are removed. 

 a. Remnant of masseter muscle; 6, internal pterygoid muscle; c, stylo-mandibularis; d, d' , levator labii superioris 

 proprius (portion removed); e, periorbita; 1, masseteric artery; /', parotid branch; 2, trunk for anterior {S) and 

 jiosterior (4) auricular arteries; 5, .5', sui^erficial temporal artery; o", transverse facial artery; 6, inferior alveolar 

 (or dental) artery; 6' , mental continuation of 6; 7, buccinator artery; S, infraorbital artery; 9, 11, jugular vein; 

 10, external maxillary vein; 12, inferior cerebral vein; IS, facial vein; 14, angular vein of eye; 15, dorsal nasal 

 vein; /6, lateral nasal vein; 77, superior labial vein; J6\ /S, inferior labial veins; .20, laliial plexu.s; ;?/, .2.2, emer- 

 gent veins of plexus; 23, vena reflexa; 24, trunk of sphenopalatine and infraorbital veins; 25, palatine vein; 

 36, great auricular vein; 27, 28, superficial temporal vein; 29, transver.se facial vein; 30, buccinator vein; 31. 

 dorsal lingual vein; 32, inferior alveolar or dental vein; 33, pterygoid vein; 34, deep temporal vein; 35, .superior 

 cerebral vein; 36, external nasal nerve; 37 , anterior nasal nerve; 3S, superior labial nerve; 39, ma.-^setcric nerve; 

 39' . end branches of 39; .^0, buccinator nerve; 41, pterygoid nerve; 41'^, inferior alveolar or dental nerve; 411^', 

 mylo-hyoid nerve; 4~, posterior auricular nerve; 43, auricular branch of vagus; 44, internal auricular nerve; J,5, 

 auriculo-palpebral nerve (cut); .^6, digastric nerve. (.After Leisering's .Atlas.) 



The lingual vein (\'. lingualis) is not a satellitt^ of the artery. It is formed at 

 the side of the lingual process of the hyoid bone by the confluence of several veins 

 which come from the substance of the tongue. Onc^ or two considerable vessels 

 run partly in the substance of the hyo-glossus, and another in the genio-hyoitleus. 

 The vein is at first covered by the mylo-hyoideus, perforates that muscle, runs 

 l)ack along the omo-hyoid(>us in relation to the submaxillary lymph glands, and 

 joins the external maxillary near the posterior border of the jaw. Near its termina- 

 tion it receives the sublingual vein, or the latter may ()])v\\ into tlie external maxil- 

 lary direct 1}'. 



8. The thyroid vein {\ . thyreoidea) is a large vessel which joins the jugular 

 near the external maxillary vein. It receives anterior tlnroid, larj'ngeal, and 

 pharyngeal radicles, and sometimes a posterior thyroid vein. 



