If you are planning a hard-to-get Alcatraz tour, you will need to really layer clothes for a variety of temperatures. The weather varies greatly from month to month and hour to hour. Even the neighborhood youre in makes a difference. For many visitors, the San Francisco weather can be counter-intuitive.
The carotid arteries are major blood vessels in the neck that supply blood to the brain, neck, and face. There are two carotid arteries, one on the right and one on the left. In the neck, each carotid artery branches into two divisions: 1  The internal carotid artery supplies blood to the brain.
The common carotid artery is a paired structure, meaning that there are two in the body, one for each half. The left and right common carotid arteries follow the same course with the exception of their origin. The right common carotid originates in the neck from the brachiocephalic trunk. The left arises from the aortic arch in the thoracic region. The left common carotid artery can be thought of as having two parts: a thoracic (chest) part and a cervical (neck) part. The right common carotid originates in or close to the neck, so it lacks a thoracic portion.