1- (right) brachiocephalic artery (or innominate artery) which goes on to divided into the right subclavian and right common carotid arteries.
2- left common carotid artery
3- left subclavian artery
There are three common variations to the branching pattern:
1. normal (as described above) that seen in ~ 70% of patients.
2. bovine arch : common origin of brachiocephalic and left common carotid artery - seen in approximately 15% of patients (more common in blacks)
3. left common carotid has its origin from the brachiocephalic artery proper, rather than from a common trunk : seen in approximately 10% of patients (also more common in blacks)
Left ICA coming off the right brachiocephalic.Additionally there may be additional branches that arise directly from the arch. These include
* thyroidea ima artery, usually between the brachiocephalic and left common carotid
* left vertebral artery, usually between the left common carotid and the left subclavian arteries.
* rarely the right subclavian and right common carotid arise independently.