VEINS OF THE HEAD AND NECK 587 



thoracic duct, which separates tlie vein from the aorta. At the seventh vertebra 

 it leaves the spine, curv(^s downward and forward over the right side of the thoracic 

 duct, trachea, and oeso]ohagus, and opens into the right atrium oi)posite the third 

 intercostal space. Its tributaries are: 



1. The last fourteen intercostal veins (Vv. intercostales) of the right side. 

 On the left side the last four to seven intercostal veins usually empt.y into the vena 

 hemiazygos. This vessel runs on the left side of the aorta from the fourteenth 

 to the eleventh thoracic vertebra, passes between the aorta and the spine, and joins 

 the vena azygos. Tn its absence its tributaries join the vena azygos. 



2. The oesophageal vein (V. o^sophagea), satellite of the ocsophagc^al artery, 

 joins the vena azygos as it inclines downward. 



3. The bronchial vein (Vena bronchialis) unites with the ])r(>ceding to form a 

 short common trunk (Ellenberger-Baum), or empties into the great coronary vein 

 (Chauveau).^ 



VEINS OF THE HEAD AND NECK 

 Jugular Veins 



The jugular veins (Vv. jugulares), right and left (Fig. 431), arise behind the 

 posterior border of the lower jaw about two and a half inches (ca. G to 7 cm.) bolow 

 the temporo-maxillary articulation by the union of the superficial temporal and 

 internal maxillary veins. Each passes downward and backward, at first eml)edded 

 more or less in the parotid gland, and continues in the jugular furrow to the thoracic 

 inlet, where it unites with its fellow and the two ])rachial veins to form the anterior 

 vena cava. In the neck it is covered l^y the skin, fascia, and panniculus, and is 

 superficial to the carotid artery, from which it is separated in the anterior two- 

 thirds of the region by the omo-hyoideus muscle.- It contains valves at the mouths 

 of its tributaries and has several pairs of semilunar valves variably disposed along 

 its course. Its tributaries are as follows: 



1. The internal maxillary vein (V. maxillaris interna) is larger than the 

 external maxillary. It may be considered to begin as the continuation l)ackward 

 of the buccinator vein where the vessel crosses the alveolar border of the mandible 

 (about two inches (ca. 5 cm.) behind the last molar tooth). It runs backward on 

 the inner surface of the ramus below the external pterygoid and covered by the 

 internal ]:)terygoid muscle for a distance of al)out three inches (ca. 7 to 8 cm.), 

 then inclines a little downward and runs ventral to the artery for about an inch 

 (ca. 2 to 3 cm.). It crosses the external face of the artery at the posterior border 

 of the jaw, and is joined by the superficial temporal vein to form the jugular. Its 

 principal radicles are: 



(1) The dorsal lingual vein (V. dorsalis linguae), which is a satellite of the 

 lingual nerve. 



(2) The inferior alveolar or dental vein (V. alveolaris mandibulse), a satellite 

 of the corresponding artery. It often unites with the preceding. 



(3) Pterygoid veins (Rami pterygoidci). 



(4) The deep temporal vein (V. temporalis profunda) is a large vessel which 

 receives tributarily fi-om the temporalis muscle and emissaries from the ])arieto- 

 temporal canal. It is connected with the anterior cerel~)ral vein and usuall}' with 



* Chaiiveau says "the bronchial veins, which ramify on the bronchi Hke the arteries of which 

 they are satellites, open into the great coronary vein very near its mouth, after having united to 

 form a single vessel, which sometimes opens directly into the atrium." Ellenberger and Baum 

 state that the bronchial and oesophageal veins open into the vena azygos separately or by a com- 

 mon trunk. Martin descril^es a short ])roncho-tt\sophageal trunk, but the vein which he figures 

 as the bronchial docs not come from tlie lungs, but is a small mediastinal vessel. The author 

 finds such a vessel entering the terminal part of the ci'sophageal vein, Init no distinct bronchial 

 vein in the horse. 



■ M'Fadyean records a case in which the vein lay on the deep face of the omo-hyoideus with 

 the carotid arteiy. 



