The =vena azygos= (Fig. 429) is an unpaired vessel which arises at the
level of the first lumbar vertebra by radicles coming from the psoas and
the crura of the diaphragm; it is connected with the first lumbar vein.
It passes forward along the right side of the bodies of the thoracic
vertebræ, in contact usually with the thoracic duct, which separates the
vein from the aorta. At the seventh vertebra it leaves the spine, curves
downward and forward over the right side of the thoracic duct, trachea,
and œsophagus, and opens into the right atrium opposite 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 empty 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. In
its absence its tributaries join the vena azygos.
2. The =œsophageal vein= (V. œsophagea), satellite of the œsophageal
artery, joins the vena azygos as it inclines downward.
3. The =bronchial vein= (Vena bronchialis) unites with the preceding to
form a short common trunk (Ellenberger-Baum), or empties into the great
coronary vein (Chauveau).[169]