8o ALLEN 



is reached it curves cephalad, following along the interhyal, 

 but above the minor hyoidean artery and the ramus h3^oideus. 

 When the preopercular is reached the course of this vein is 

 dorsad behind the ramus hyoideus and when a little past the 

 middle of the preopercular, it passes with the nerve to the outer 

 surface of the hyomandibular through a foramen between the 

 hyomandibular and the preopercular. Here it receives a ven- 

 tral branch from the posterior part of the adductor mandibul^e 

 muscle, which follows along the outer surface of the preoper- 

 cular. The main stem then leaves the hyoidean ramus and 

 continues obliquely cephalad a little ventrad of the levator 

 arcus palatini and between the superficial and profundus por- 

 tions of adductor mandibulas, to unite with the facialis-man- 

 dibularis vein. The combined trunk proceeds dorsad for 

 a short distance between the ramus mandibularis V and the 

 facial artery to the floor of the orbit ; where it receives the 

 facialis-maxillaris vein. 



Facialis-maxillaris Veins (Pis. I and III, figs, i, 17, and 18; 

 F.Max. v.). — Each of these vessels has its origin from a dorsal 

 and a cephalic branch. The larger dorsal branch arises as an 

 anastomotic vein from the orbito-nasal vein (see fig. 18) ; pass- 

 ing beneath the nasal sac some little distance cephalad of the 

 corresponding artery it receives at the level of the ventral surface 

 of the nasal sac a rather large vein coming from the region of 

 the palatine arch ; and then continuing ventrad a short distance 

 the main stem passes under the maxilla artery and unites with 

 the maxilla vein. The viaxilla vein (Pis. I and III, figs, i and 

 17 ; Max.V.) has its source in a superficial and a profundus 

 branch from the premaxilla, which unite in the region of the 

 vomer. In its caudal course it receives several branches from 

 the anterior part of the adductor mandibulas muscle. After 

 uniting with the dorsal branch from the region of the nasal sac 

 the facialis-maxillaris vein proper crosses over the small facialis- 

 maxillaris artery, and continuing caudad between the ramus 

 maxillaris V or ramus maxillaris superior and the facialis- 

 maxillaris artery in the adductor arcus palatini from which it 

 receives several branches, it unites witii the combined trunk of 

 the mandibular and hyoidean veins in the posterior part of the 

 orbit to form the external jugular trunk. 



