The carotid artery is a major artery located in the front of the neck. Through the carotid artery, blood from the heart goes to the brain. There are 2 "common" carotid arteries -- the right and left common carotid arteries -- one on each side of the neck. Together, the right and left common carotid arteries provide the principal blood supply to the head and neck.
The left common carotid arises directly from the aorta (the huge artery that distributes blood from the heart to the body). The right common carotid artery arises from the brachiocephalic artery which, in turn, comes off the aorta.
Each of the two common carotid arteries divides to form external and internal carotid arteries. The external carotids are more superficial (closer to the surface) than the internal carotids (which run deep within the neck).
Carotid comes from the Greek "karotides" which referred to the main arteries going to the head. Interestingly, "karotides" is related to the words "katotikos", stupifying and "karos", deep sleep. The ancient Greeks knew that firm pressure on the carotid arteries produced "deep sleep" by rendering a person unconscious.
To translate medical terms into everyday English and dispel the mystique surrounding them, visit the MedicineNet.com Medical Dictionary, www.MedTerms.com. There you will find entries, such as this one on the carotid artery.