4.2. The Aortic Arch
Three Branches of the Aortic Arch
The following three branches of the aortic arch are vital to know. Make a big effort to remember these, especially which arteries are 'left' and 'right'. Look at the diagram for visual help.
1. Brachiocephalic trunk
2. Left common carotid artery
3.Left subclavian artery
Appreciate the lack of symmetry of the aortic branches...
On the right side, the brachiocephalic trunk gives rise to the right common carotid and the right subclavian. However, on the left side, the left common carotid AND the left subclavian come directly off the aortic arch.
The ascending aorta, aortic arch and descending aorta are directly continuous with each other.
The descending aorta (also called the thoracic aorta) will give rise to most of the posterior intercostal arteries. The thoracic aorta is also directly continuous with the abdominal aorta. Basically, once the thoracic aorta passes through the aortic hiatus at T12, it is renamed the abdominal aorta.
The common carotids will go on to supply the head and neck (external will supply the superficial head and neck...internal will supply the brain).
The subclavian arteries supply the axillae (armpits) and arms. Each artery becomes directly continuous with the axillary artery of that side.
The internal thoracic arteries run posterolaterally on either side of the sternum. So, overall, within the thorax, these lie very anteriorly. Remember from Section 2.4.1. the internal thoracic vessels are held in place by the transversus thoracis muscle.
Note also that the aortic arch lies in the sternal plane and behind the manubrium of the sternum. The sternal plane is an imaginary line drawn from the manubriosternal joint and the intervertebral disc between T4/T5 - check out Section 7.1. for more info.