318 THE CIRCULATORY SYSTEM. 
the cranial intercostal spaces usually unite two or three 
together and enter the azygos by one or more common trunks. 
The azygos also receives bronchial and cesophageal veins, 
corresponding to the similarly named arteries. 
2. V. mammaria interna (g).—The internal mammary 
veins follow the corresponding arteries. The two veins unite 
to form a common trunk which, after receiving a branch from 
the cranial part of the sternum, enters the vena cava opposite 
the third rib. 
3. Vv. anonyme (Fig. 129, m; Fig. 115, ~).—The in- 
nominate veins unite opposite the first intercostal space to form 
the vena cava superior. Each extends from the cranial end of 
the vena cava superior craniolaterad to a point a short distance 
craniad of the first rib and is there formed by the union of the 
external jugular (Fig. 129, £) and subclavian (7) veins. The 
innominate vein has the following branches: 
A and B. Vv. vertebralis and costocervicalis (¢).—The 
vertebral and costocervical veins unite to form a single trunk 
which enters the innominate about opposite the first rib. 
These two veins follow the corresponding arteries. (Some- 
times the vertebral and costocervical veins enter the innominate 
separately, and in other cases one or more of the components 
of the costocervical veins (e.g., the transversa colli) may enter 
the axillary vein. In other cases the entire common trunk of 
the vertebralis and costocervicalis may enter the superior vena 
cava directly.) 
C. V. subclavia.—The subclavian vein enters the innom- 
inate at about the level of the first rib. Outside of the thorax 
it is called the axillary vein (/); this comes from the arm. 
Veins of the Arm.—The blood is returned from the arm 
by two systems of veins,—a deep and a superficial system. 
The deep system is Composed of veins which correspond to 
the branches of the axillary artery, follow in general the same 
course, and receive the same names (Fig. 122). They unite to 
form the axillary vein. The brachial vein does not pass with 
the brachial artery through the supracondyloid foramen. 
The superficial system comprises the vena cephalica and 
its branches. 
