What and Where is the Neck Carotid Artery? Common, Internal, External
The carotid arteries are a group of arteries that rise up the neck to supply oxygenated blood to the brain, face and many other parts of the head. It is not the only supply of arterial blood to these areas but it is among the most significant. Injury, occlusion (blockage) or any rupture of these arteries can be life threatening.
Common Carotid Artery
The aorta is the large artery that carries oxygenated blood out of the heart and distributes this blood throughout the body. Two carotid arteries arises directly or indirectly from the aortic arch :
- Right common carotid artery
- Left common carotid artery
Right Common Carotid Artery
The right common carotid artery does not branch off directly from the aorta. The brachiocephalic trunk which is the first and largest branch of the aortic arch divides into the right common carotid artery and right subclavian artery. This branching of the brachiocephalic trunk occurs to the right of the trachea around the level of right sternoclavicular joint – where the clavicle (collar bone) articulates with the uppermost part (manubrium) of the sternum (breastbone).
Left Common Carotid Artery
The left common carotid artery arises directly from the arch of the aorta. It is the second branch and starts just behind the manubrium of the sternum. It passes across the trachea (anterior) and then runs up into the neck to the left of the trachea and behind the left sternoclavicular joint.
Picture from Wikimedia Commons
Carotid Triangle
The right and left common carotid arteries run up the neck on the respective side in the carotid sheath along with the internal jugular vein and vagus nerve. It enters an area that is known as the a carotid triangle. Here it can be easily felt (palpated) or heard with a stethoscope (auscultated) as the carotid pulse.
At the upper part of the carotid triangle, the common carotid artery divides into the internal and external carotid arteries. This bifurcation occurs at the level of the superior border of the thyroid cartilage of the larynx (voice box).
Picture from Wikimedia Commons
There are two important structures that are situated around the branching of the common carotid artery – the carotid sinus and the carotid body. Both these structures perform vital functions in monitoring the blood and are innervated by the carotid sinus nerve which is a branch of the glossopharyngeal nerve (CN IX), as well as the vagus nerve (CN X).
Carotid Sinus
This is the small balloon like structure at the start of the internal carotid artery. The dilation sometimes extends to the common carotid artery. The carotid sinus is a barometer that monitors arterial blood pressure.
Carotid Body
This is a small oval mass located at the bifurcation of the common carotid artery, between the two branches – internal and external carotid arteries. It is a chemoreceptor that monitors the oxygen levels in the blood.
Internal Carotid Artery
The internal carotid artery is more of a small continuation of the common carotid artery unlike the external carotid artery that diverges off the common carotid. It runs up the neck, enters the carotid canal in the skull and becomes one of the main arterial blood supplies to the brain and eyes.
There are no branches from the internal carotid artery in the neck region.
Picture from Wikimedia Commons
External Carotid Artery
This is the second terminal branch of the common carotid artery. It gives off many branches along its course which supplies different parts of the face and head. It eventually terminates into the two branches mentioned below.
Branches of the external carotid artery :
- Ascending pharyngeal artery
- Occipital artery
- Posterior auricular artery
- Superior thyroid artery
- Lingual artery
- Maxillary artery (terminal branch)
- Superficial temporal artery (terminal branch)
