OF THE GREAT ANTERIOR VEINS. 
159 
Transposition of the great anterior veins may be further complicated by subordi- 
nate varieties, as for example, in the intercostal systems ; and it is interesting to find 
that one of the most remarkable of the deviations met with in the azygos vein when 
holding its customary position, has been observed also in the transposed vein ; viz. 
its excessive enlargement to enable it to return the blood from the lower half of the 
body, in cases where the inferior cava is deficient, and is represented only by the 
trunk of the hepatic veins*. 
Lastly, the great anterior veins do not appear ever to undergo transposition, unless 
the heart itself be reversed'!'. 
Group B. The second anterior venous trunk, an azygos venous trunk existing on the 
left side, or by transposition on the right . — This condition, which is regular in the 
Sheep, Ox, Goat, Pig, &c., has not, as far as I know, been met with as a deviation in 
the human subject, even in the most complex forms of transposition or malformation; 
but it is here referred to as one that may possibly be yet detected 
In the cases hitherto recorded as examples of a left vena azygos in Man, the un- 
usual vein, as already fully particularized (pp. 156, 157), has ended in some of the 
branches or in the trunk of the vena cava superior. A true left vena azygos, however, 
sometimes exists in the human subject, in connection with an additional superior 
cava, as will immediately be shown. 
Group C. The second anterior venous trunk, an additional vena cava superior. 
a. Without transposition. In these cases the heart and great vessels, as well as 
the other viscera, holding their usual position, the superadded vein is a left superior 
cava. This condition constitutes that interesting variety of the great anterior veins 
commonly named double vena cava superior, in which the arrangement of the vessels 
* Herholbt (Abhandlung der K. Acad, zu Kopenhagen, 1818). 
M'Whinnie (London Med. Gazette, 1840). The preparation is in St. Bartholomew’s Hospital Museum, 
and is figured in Quain’s “Anatomy of the Arteries,” &c. (pi. 5. fig. 4). In both of these instances the 
transposed azygos receives all the branches of the inferior cava excepting the hepatic veins, and turns over the 
left bronchus to end in the ordinary upper cava, which, however, is on the left side. 
t In an interesting case recorded by Wilson in the Philosophical Transactions, a vena cava superior, 
together with a perfect vena azygos, is found on the left side only of the thorax. This does not appear to 
have been an example of transposition of the right vein over to the left side ; but rather one in which, the heart 
being reduced to a single auricle and a single ventricle and not transposed, the ordinary right upper cava is 
entirely wanting, whilst a true left upper cava alone exists, pursuing, as usual, a circuitous course to the heart 
(Philosophical Transactions, 1798, p. 346, with a plate). A case of ectopia cordis. The child lived seven 
days. 
Standert (Philosophical Transactions for 1805, Part II. p. 228) gives an account of a child’s heart, with 
undivided auricles and ventricles, in which the same condition of the veins, as far as can be understood from 
the figure, appears to have existed. 
+ Could the statement and figures of Vieussens {loc. cit.) be considered free from all doulit, the so-called 
vein of the pericardium, which returned the blood from the outside of that sac, and descended in the position of 
the oblique vein into the coronary sinus, might be conceived to have been a true left azygos venous trunk, 
formed by a persistent left canal of Cuvier (see p. 147). 
