Carotid Sinus
The structure indicated is the
carotid sinus.
The carotid sinus is located just above the
bifurcation of the
common carotid artery at the base of the
internal carotid artery.
The carotid sinus is an important structure in regulating and maintaining
blood pressure. It contains
baroreceptors which are sensitive to increases in arterial blood pressure and subsequent increased pressure and stretching of the arterial walls. The carotid sinus receives innervation via cranial nerve IX (
glossopharyngeal nerve). This nerve synapses in the
nucleus tractus solitarii of the
medulla oblongata which then indirectly adjusts the level of autonomic outflow and controls the body’s blood pressure by altering the
cardiac output and
smooth muscle tone in the vasculature.
Also located at the bifurcation of the common carotid artery are
chemoreceptors which detect changes in the partial pressure of
oxygen and
carbon dioxide in the blood. This collection of chemoreceptors are known as the
carotid body, and receives innervation via cranial nerves IX and X.