There is no common brachiocephalic trunk (anterior aorta). Two large
vessels arise from the convexity of the aortic arch; these are the
=brachiocephalic= and =left brachial arteries=. The =brachiocephalic=
gives off the two =carotid arteries=, no common trunk being present. It
frequently also supplies the posterior thyroid artery. The intrathoracic
branches of the brachial arteries are as follows:
A common trunk gives off the =dorsal=, =subcostal=, and =superior
cervical arteries=. The dorsal artery passes out in front of the first
rib, and the superior cervical through the first intercostal space. The
latter is relatively small.
[Illustration: