112 FISTULA AND POLL-EVIL 
brae. It inserts to tubercles which occur at 
the junction of the basilar part of the occipital 
bone with the body of the sphenoid. These 
muscles (the pair) may be said to form a roof 
for a part of the pharynx. 
The blood supply of the poll is from three 
sources: The occipital, the superior cervical 
and the vertebral arteries. The first named 
is, however, the chief one. It is a radical of 
the carotid and passes to the region of the poll 
through the large foramen in the wing of the 
atlas. Its branches anastomose with the other 
two. The branches are numerous and often 
through the influence of the disease become 
greatly enlarged. In the operation for poll- 
evil the incision being a standard one, made 
irrespective of blood vessels, there is nothing of 
importance to say about avoiding them, ex- 
cept that lateral invasion into the region of the 
alar foramen through which the occipital passes 
must be made cautiously. In short, no especial 
effort except this one, is ever made to avoid 
arteries. 
The nerve supply is of no especial impor-- 
tance. It is derived from the spinal accessory 
and the first two spinal nerves, none of which 
is ever seen in the operation, nor is a solution 
on the continuity of their branches attended 
with any observable harm. 
