Carotid sinus

Carotid sinus
Arteries of the neck. The carotid sinus is at the origin of the internal carotid artery.
Details
Artery	carotid artery
Nerve	branch of glossopharyngeal nerve to carotid sinus
Identifiers
Latin	sinus caroticus
MeSH	A07.231.114.186.456
TA	A12.2.04.008
FMA	50094
Anatomical terminology []

In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid sinus extends from the bifurcation to the "true" internal carotid artery {Pellerito & Polak 2012}. The carotid sinus is sensitive to pressure changes in the arterial blood at this level. It is the major baroreception site in humans and most mammals.

The carotid sinus is the reflex area of the carotid artery, consisting of various nerve receptors for baroregulation (pressure regulation of the body in sync to external conditions).

The carotid sinus contains numerous baroreceptors which function as a "sampling area" for many homeostatic mechanisms for maintaining blood pressure. The carotid sinus baroreceptors are innervated by the sinus nerve of Hering, which is a branch of cranial nerve IX (glossopharyngeal nerve). The glossopharyngeal nerve synapses in the nucleus tractus solitarii (NTS) located in the medulla oblongata of the brainstem. The NTS indirectly modulates the activity of sympathetic and parasympathetic (vagal) neurons in the medulla and pons through the hypothalamus. These neurons then regulate the autonomic control of the heart and blood vessels. The aortic arch baroreceptors are innervated by the aortic nerve (Nerve of Cyon), which combines with CN X (vagus nerve) and travels to the NTS.

It is a sensitive site of the body which can cause lethal effects to the body (rapid increase in blood pressure, cerebral ischemia, etc.) upon strong stimulation manually or by other means, e.g. Transcutaneous electrical nerve stimulation in any of the three modes.