The branches

of the blood-vessels lie above the tubes that
extend from the windpipe. And that vessel which extends to the
vertebra of the neck and the backbone, stretches back again along
the backbone; as Homer represents in the lines:-

(Antilochus, as Thoon turned him round),

Transpierc'd his back with a dishonest wound;

The hollow vein that to the neck extends,

Along the chine, the eager javelin rends.

From this vessel there extend small blood-vessels at each rib
and each vertebra; and at the vertebra above the kidneys the vessel
bifurcates. And in the above way the parts branch off from the great
blood-vessel.