686 BLOOD-VASCULAR SYSTEM OF THE HORSE 
The upper one is the transverse facial vein, which unites close to the end of 
the facial crest. 
A little lower is the large valveless vena reflexa, or alveolar vein. This passes 
back under the upper part of the masseter on the maxilla, turns around the tuber 
maxillare, perforates the periorbita, and joins the ophthalmic vein. — It is relatively 
small at each end, but presents one or two large fusiform dilatations. Its posterior 
part is embedded ina mass of fat. It 
receives the following tributaries: (a) 
The great palatine vein (V. palatina 
major), separates from the palatine 
artery at the anterior palatine 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 anteriorly. 
(b) The sphenopalatine vein (V. 
sphenopalatina) is the satellite of the 
artery; it forms a rich plexus of valve- 
less vessels on the turbinate bones 
and the septum nasi. The venous 
plexuses are remarkably developed in 
certain parts of the nasal mucosa. 
On the septum a little below its 
middle and on the turbinates the 
veins are in several layers. The ol- 
factory region does not share in this 
arrangement, and the veins here are 
small and join the ethmoidal vein. 
(c) The infraorbital vein (V. infra- 
orbitalis) is also a satellite of the ar- 
tery; it usually unites with the spheno- 
palatine to form a short common 
trunk. (d) The ophthalmic vein (V. 
ophthalmica) is a short trunk, which 
is connected in front with the vena 
Fre. 587.—Dissncrion or Manpimurar Space anp Ap reflexa and behind with the cavemomg 
JACENT Parr or Neck or Horse. sinus through the foramen orbitale. 
a, Ramus of mandible; 6, sterno-cephalicus muscle; It receives veins which correspond to 
c, ce’, omo-hyoidei and sterno-hyoidei (portion removed on Swaeaeie a ahec 
right side); d, hyoid bone; e, anterior belly of digastricus; th arterial br anches. 
f, g, mylo-hyoideus; h, mandibular lymph glands (portion The buccinator vein (V. buccin- 
removed on right side); 7, parotid gland; ’, mandibular  gtoria) extends backward from the ex- 
salivary gland; l, chin; m, occipito-mandibularis; 1, parotid arene aaelNaaee 
duct; 2, facial vein; 3, facial artery; 4, external maxil- ternal maxillary along the ventral bor: 
lary vein; 4, lingual vein; 6, sublingual artery; 7, ventral der of the depressor labu inferioris and 
branch of first cervical nerve; 8, mylo-hyoid nerve. (After buecinator under cover of the mas- 
Ellenberger, in Leisering’s Atlas.) a s 
seter, turns medially over the ramus 
of the mandible about two inches (ca. 
5 em.) behind the last molar tooth, and is continued as the internal maxillary vein. 
It has a large fusiform dilatation and is valveless. It receives a large vein from 
the buceal plexus, and is usually connected with the masseteric vein. 
The lingual vein (V. lingualis) 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. One or two considerable vessels run partly in the substance of the hyo- 
