The brachiocephalic trunc is the first large arterial branch of the aorta. Historically, it also has been called "Anonymous artery", or "Unnamed artery".
The brachiocephalic trunc just occurs on the right side of the body in most humans. It comes from the aortic arch and is the common vascular trunc of the right subclavian artery and the right common carotid artery. On the left side, the vessels usually arise separately from the aortic arch.
In some cases, also the left common carotid artery can arise from the brachiocephalic trunc as a variation.