Where is the carotid sinus located? Common, internal? R or L?

The carotid sinus is in the internal carotid artery, immediately after the division of the common carotid artery into the external and internal carotid arteries. In some people the sinus extends into the common carotid artery. Both the right and left internal carotid arteries have a carotid sinus. The sinus is formed by a dilation of the lumen of the artery. In terms of external anatomy, the carotid sinus is located in the neck on either side at about the level of your larynx (voice box). The walls of the carotid sinus contain baroreceptors (receptors that are sensitive to the stretch in the walls of the sinus) that monitor the blood pressure in the sinus and send signals to the cardiovascular control center in the brain for blood pressure regulation. Another group of receptors called the carotid body is also associated with the carotid sinus. However, the carotid body is anatomically and functionally distinct from the carotid sinus. The receptors of the carotid body are involved in sensing the pH, oxygen, and carbon dioxide levels in the blood and extracellular fluid and sending signals back to the respiratory centers in the brain for regulation of breathing. You can find a nice picture showing the location of the carotid sinus at http://www.cvrx.com/medpros/products.php. You should also be able to find a picture and discussion of the carotid sinus in the chapter on the cardiovascular system of any human anatomy textbook.