The carotid sinus is a small dilation located at the base of the internal carotid artery, near where it branches from the common carotid artery. It plays a crucial role in regulating blood pressure by detecting changes in blood flow and pressure. Specialized nerve endings in the carotid sinus send signals to the brain, helping to maintain stable blood pressure levels. This structure is part of the body's baroreceptor system, which monitors and responds to fluctuations in blood pressure. When blood pressure rises, the carotid sinus sends signals to decrease heart rate and dilate blood vessels, promoting better circulation and preventing hypertension.