In humans, the arch of the aorta has three main branches that deliver blood to the head and arms. The cat only has two vessels that branch directly from the aorta. Many of the cat diagrams will show the following diagram to help you locate the brachiocephalic artery, the left and right subclavian arteries, and the left and right common carotids.
The problem with diagrams such as these is that the cat doesn’t always look exactly like this. On the photo below, common carotids and the right subclavian artery look as though they branch from the same spot on the brachiocephalic. Dissection of this artery can be challenging because the specimens can vary in their appearance. Also, many reference books refer to the brachicephalic aretery as the innominate artery.