left common carotid artery (anatomy)

Last reviewed 01/2018

The left common carotid artery arises within the superior mediastinum as the second main branch of the aortic arch. It originates posterior and to the left of the first branch, the brachiocephalic trunk. As it ascends its relations are:

• anterior:
• left brachiocephalic vein
• thymic remnant
• posteriorly:
• and inferiorly:
• left subclavian artery laterally
• trachea medially
• and superiorly:
• trachea
• left recurrent laryngeal nerve
• left anterior surface of oesophagus
• right:
• brachiocephalic artery
• inferior thyroid veins
• trachea
• left:
• vagus nerve
• phrenic nerve more laterally
• cervical pleura

Within the neck, the left common carotid passes from deep to the sternoclavicular joint within the carotid sheath superiorly and slightly posteriorly. Within the sheath it is sited medial to the internal jugular vein with the vagus nerve interposed between them.

The artery gives off no branches before its terminal division posterolateral to the larynx just inferior to the level of greater horn of the hyoid bone. Here it forms the carotid sinus and it divides into the left internal and external carotid arteries.

It is used to assess the waveform of the carotid pulse.