These two vessels (Arteriæ carotides communes) arise from the
brachiocephalic artery by a common trunk. This stem, the =truncus
bicaroticus= or =cephalic artery=, is detached from the inner face of
the brachiocephalic opposite the first rib and passes forward in the
median plane beneath the trachea. It is related ventrally to the
prepectoral lymph glands, the terminal parts of the jugular veins, and
the anterior vena cava, and laterally to the vagus and recurrent nerves.
It is commonly two or three inches (ca. 5 to 7 cm.) in length, but it
may vary between one and eight inches (ca. 2.5 to 20 cm.).
[Illustration: