THE ANTERIOH VENA CAVA. 603 



Before traversing the ocular sh ath, and towards the maxillary hiatus, 

 this vein receives the superior dental and the confluent of the nasal veins : 

 vessels which emerge from the bony orifices traversed by the arteries of the 

 same name that is, the maxillo-dental canal and the nasal foramen. It also 

 receives the confluent of the palatine veins, which pass by the palatine groove, 

 instead of coursing along the palatine canal with the corresponding artery. 

 In general, these three branches do not join the alveolar separately, but 

 rather by a common trunk. 



The alveolar vein does not present a uniform volume. It increases from 

 before to behind to the maxillary protuberance, where it forms a kind 

 oflarge reservoir ; but in traversing the ocular sheath it suddenly becomes 

 constricted, and maintains a small diameter until its entrance into the 

 cavernous sinus. 



This vein may be considered as an affluent of the sinuses of the dura 

 mater, as well as of the external maxillary vein. 



b. Labial or coronary veins. Satellites of the labial arteries. The 

 superior is often rudimentary. The inferior, always voluminous, is 

 constituted by the union of several anastomotic branches lying against the 

 external face of the mucous membrane of the cheek. 



c. Buccal vein. Among the affluents of the external maxillary vein, 

 we cite this, because it opens into the latter by its anterior extremity, 

 opposite the inferior coronary vein, with which it sometimes communicates 

 by a particular branch. But the buccal vein, properly speaking, con- 

 stitutes the root of the internal maxillary, and we will describe it as such. 



d. Sublingual vein. A large vessel, formed of two branches, which arise 

 in the substance of the tongue, and are sometimes thrown separately into the 

 internal maxillary vein. This sublingual vein passes through the mylo- 

 hyoidens muscle, from within to without, and joins the principal vessel at 

 the lymphatic glands lodged in the intermaxillary space. 



E. THYROID VEIN. This is a voluminous trunk, resulting from the 

 union of the venous divisions which accompany the laryngeal and thyroid 

 branches of the thyroid or thyro-largyngeal artery. It joins the jugular 

 beside the external maxillary vein, and most frequently above it. 



F. CEPHALIC OR PLAT VEIN. A superficial vessel, which represents 

 one of the terminal branches of the principal subcutaneous vein of 

 the fore-arm. It is lodged in the interstice of the levator humeri and 

 small pectoral muscles, and enters the inferior extremity of the jugular 

 vein (Fig. 293). 



G. INNOMINATE VEINS. A certain number come from the parotid 

 gland, but the principal arise in the muscles of the neck and withers. One 

 of the latter accompanies the superior branch of the cervico-muscular 

 artery. 



ROOTS OF THE JUGULAR VEIN. 



These are constituted by the superficial temporal and internal maxillary 

 veins, which are chiefly fed by the sinuses of the encephalic dura mater. 



1. Superficial Temporal Vein. 



Corresponding in the most exact manner to the temporal trunk, this 

 vessel is lodged behind the posterior border of the maxilla, near the articula- 

 tion of the jaw, beneath the parotid gland, and is, as it were, incrusted in 



its tissue. 



