the basilar process
of the occipital bone; or else by a direct end-to-end union, of which
the lateral pair of cerebral arteries, forming the circle of Willis, and
the two labial arteries, forming the coronary, are examples. The
branches of the main arteries of one side form numerous anastomoses in
the muscles and in the cellular and adipose tissue generally. Other
special branches derived from the parent vessel above and below the
several joints ramify and anastomose so very freely over the surfaces of
these parts, and seem to pass in reference to them out of their direct
course, that to effect this mode of distribution appears to be no less
immediate a design than to support the structures of which the joints
are composed.

XII.--The innominate artery. When this vessel is tied, the free direct
circulation through the principal arteries of the right arm, and the
right side of the neck, head, and brain, becomes arrested; and the
degree of strength of the recurrent circulation depends solely upon the
amount of anastomosing points between the following arteries of the
opposite sides. The small terminal branches of the two occipital, the
two auricular, the two superficial temporal, and the two frontal,
inosculate with each other upon the sides, and over the vertex of the
head; the two vertebral, and the branches of the internal carotid, at
the base and over the surface of the brain; the two facial with each
other, and with the frontal above and mental below, at the median line
of the face; the two internal maxillary by their palatine, pharyngeal,
meningeal, and various other branches upon the surface of the parts to
which they are distributed; and lastly, the two superior thyroid
arteries inosculate around the larynx and in the thyroid body. By these
anastomoses, it will be seen that the circulation is restored to the
branches of the common carotid almost solely. In regard to the
subclavian artery, the circulation would be carried on through the
anastomosing branches of the two inferior thyroid in the thyroid body;
of the two vertebral, in the cranium and upon the cervical vertebrae; of
the two internal mammary, with each other behind the sternum, and with
the thoracic branches of the axillary and the superior intercostal
laterally; lastly, through the anastomosis of the ascending cervical
with the descending branch of the occipital, and with the small lateral
offsets of the vertebral.

XIII.--The common carotid arteries