JUGULAR VEINS 



589 



down over the chook alonp; the anterior border of the masseter niusele behind the 

 artery, crossing over the i)aroti(l chict, wliieli Ues ])ehind the vein lower down. Thus 

 on the ramus and as they turn around its lower border the artery is in front, the vein 

 in the middle, and the duct posterior. In the sul^maxillary space the vein is ventral 

 to the artery for some distance, then parts company with the artery, runs straight 

 backward along the lo\\er ])order of the parotid gland, and oi)ens into the jugular 

 vein at the posterior angle of the 

 gland.' The chief differences in the 

 tributaries of the vein as compared 

 with the branches of the correspond- 

 ing artery are as follows: 



The labial veins (\'v. labiales) 

 form a plexus in the sul)mucous tissue 

 of the cheek from which two veins 

 emerge. The upper one passes back 

 and joins the buccinator vein. The 

 lower one (V. labialis communis) 

 joins the external maxillary vein. 



Three veins connect witli the ex- 

 ternal maxillary at the anterior border 

 of the masseter. 



The upper one is the transverse 

 facial, which unites close to the end 

 of the facial crest. 



A little lower is the large valve- 

 less vena reflexa or alveolar vein. 

 This passes back under the upjMT 

 part of the masseter on the maxilla, 

 turns around the tuber maxillare, per- 

 forates the periorbita, and joins tlie 

 ophthalmic vein. It is relatively 

 small at each end, but ]:> resents one 

 or two large fusiform tlilatations. It 

 receives the following tributaries: (a) 

 The palatine vein (^^ })alatina major), 

 which separates from the palatine 

 artery at the anterior ])alatine fora- 

 men and passes in the groove between 

 the tuber maxillare and the palate 

 bone. The palatine veins form a 

 very rich plexus of valveless vessels 

 in the submucosa of the hard palate, 

 which consists of several layers an- 

 teriorly, (b) The sphenopalatine 

 vein (V. spheno-palatina) forms a 

 rich plexus of valveless vessels on 

 the turbinal bones and the septum 



nasi. It is usually joined by the infraorbital vein (V. infraorbitalis) to form a short 

 common trunk. 



Tlie venous plexuses are remarkably developed in certain parts of the nasal mucosa. On 

 the septum a little below its middle and on the turbinals the veins are in several layers. The 

 olfactory region does not share in this arrangement and the veins here are small and join the eth- 

 moidal vein. 



Fir.. 462. — Dissection of SrnM.\xiLLARY Space and 

 Adjacknt P.\rt of Neck of Horse. 

 a. Ramus of mandible; b, sterno-cephalicus muscle; 

 c, c', omo-hyoidei and .sterno-hyoidei (portion removed on 

 right side) ; d, hyoid bone; e, anterior belly of digastricus; 

 /, g, mylo-hyoideu.s; h. submaxillary lymph glands (por- 

 tion removed on right side): i, parotid gland; k, submaxil- 

 lary gland; I. chin; m. stylo-maxillaris; 1. parotid duct; 

 2, facial vein; S, facial artery; 4. external maxillary vein; 

 5, sublingual vein; 6, sublingual artery; 7, ventral branch 

 of first cervical nerve; 8. mylo-hyoid nerve. (After 

 Ellenberger, in Leisering's Atlas.) 



' The venous angle formed by this junction indicates the position of the thyroid gland. 



