452 
Philippine Journal of Science 
1919 
three instances of the abnormality in the origin of the left ver- 
tebral artery. In these the vessel arose directly from the arch 
of the aorta between the left common carotid and the left sub- 
clavian. He also found, in the same series, five cases of varia- 
tion. In every case it arose from a common trunk, from part 1 
of the subclavian in association with other arteries ; three times 
with the inferior thyroid; once with the thyroid axis; and in 
one instance the right vertebral artery was double. 
While it is a well-known fact that normally only three branches 
are given oif from the aortic arch, yet there are cases where 
four or more vessels take origin from it. In the great majority 
of such instances, according to Thane, (8) the left vertebral ar- 
tery originates from the arch between the left common carotid 
and the left subclavian, and only in rare instances between the 
right common carotid and the right subclavian. 
In my series, I found two cases where the left vertebral artery 
originated from the aortic arch between the left common carotid 
and the left subclavian. In one instance (case 38) it ascended 
in front of the transverse processes of the lower cervical verte- 
brae until it reached the level of the third vertebra, there en- 
tering the foramen transversarium. In case 39, after following 
a similar vertical course, it entered the transverse foramen of 
the fifth cervical vertebra. The right vertebral artery in both 
cases was entirely normal (see Plate I, figs. 1 and 2). 
Bean’s observations, as well as mine, appear to confirm 
Thane’s statement as to the more frequent aortic origin of the 
left vertebral artery between the left common carotid and the 
left subclavian. 
Thirteen of the remaining cases in my series, while apparently 
normal in origin, showed abnormalities in the point of entrance 
to the foramen transversarium. To this number must be added 
the two cases described above which, besides having abnormal 
origin, also showed variations in the point of entrance to the 
transverse foramina. 
The cases are classified into two groups ; namely, cases show- 
ing the same bilateral point of entrance and cases in which the 
point of entrance differed on both sides. 
There were six cases in group 1 (see Table I). In four the 
arteries entered the transverse foramen of the seventh cervical 
vertebra ; in one, the foramen of the fifth ; and in the other, that 
of the fourth cervical vertebra. 
Nine cases were placed under group 2 (see Table II). Here 
there were five instances where the right artery entered the 
