NOTES ON THE BRANCHES OF THE AORTA (ARCUS 
AORTAE) AND THE SUBCLAVIAN ARTERY 
OF THE RABBIT 
FRANCIS MARSH BALDWIN 
One plate (VIII) of eleven figures. 
Bensley ^ in his Practical Anatomy of the Rabbit (p. 365), 
in discussing the blood vessels of the thorax describes the arch 
of the aorta as “beginning at the base of the heart, — — 
passes forward, and then describing a curve, in the course of which 
it lies slightly to the left of the median plane, turns backward 
along the ventral surfaces of the bodies of the thoracic vertebrae. 
With the exception of the coronary arteries the first branches are 
the large paired vessels arising from the anterior wall. They 
comprise the common carotid and subclavian arteries. On the 
right side the carotid and subclavian arise from a short common 
trunk, the innominate artery. The left common carotid arises 
immediately to the left of this vessel or from its base. The sub- 
clavian artery (a. subclavia) is the first portion of the artery 
of the anterior limb. It passes from its point of origin laterad 
to the anterior margin of the first rib, where it is replaced by the 
axillary artery. Near its point of origin, it gives ofif several 
branches, the relations of which are subject to considerable varia- 
tion.” 
“The large paired vessels” referred to above is not exact and 
leads to confusion, since even in the usual condition it applies 
to neither the right and left common carotid arteries, nor the 
paired subclavian arteries, but to an innominate artery on the 
right side, and the left subclavian artery on the other. That the 
left common carotid artery usually arises immediately to the 
left of the base of the innominate is perhaps correct, although 
in by far the greater number of rabbits dissected by the writer 
the origin of this vessel is well up on the mesial side of the in- 
nominate. In cases where the left common carotid artery arises 
to the left of the innominate, there would be three vessels arising 
from the cephalic curve of the aorta and not two (a pair) as 
above described, a condition normally found in the human. With 
reference to the subclavian arteries, the statement as to their 
