Bovine Arch

This surface shaded CTA of the aortic arch, demonstrates the left common carotid artery originating in common with the brachiocephalic artery (see diagram here). Indeed it is in this case almost a branch of the brachiocephalic artery, another recognized pattern (see diagram here). This pattern is commonly referred to as a “bovine arch” although it should be noted that this bears little resemblance to a true bovine aortic arch. In cattle (in which it must be easier to perform a four vessel angiogram - at least if you manage to get the udders out of the way of the groin puncture) the carotids and subclavians have their origin as a giant single trunk (see diagram here)
Credit: Dr Frank Gaillard
http://www.radpod.org