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Carotid sinus

 
Carotid Sinus

 
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Carotid sinus
 
 
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In human anatomy
Human anatomy

Human anatomy, which, with physiology and biochemistry, is a complementary basic medical science is primarily the scientific study of the morphology of the adult human body....
, the carotid sinus is a localized dilation of the internal carotid artery
Internal carotid artery

In human anatomy, the internal carotid artery is a major artery of the head and neck that helps supply blood to the brain....
 at its origin, the common carotid artery
Common carotid artery

In human anatomy, the common carotid artery is an artery that supplies the head and neck with oxygenated blood; it divides in the neck to form the external carotid artery and internal carotid artery....
 bifurcation
Bifurcation

Bifurcation means the splitting of a main body into two parts.Bifurcation or Bifurcated may refer to:*Bifurcation , the division of issues in a trial for example the division of a page into two parts....
.

ontains numerous baroreceptors, which function as a "sampling area" for many homeostatic
Homeostasis

Homeostasis is the property of a system, either open system or closed system, that regulates its internal environment and tends to maintain a stable, constant condition....
 mechanisms for maintaining blood pressure
Blood pressure

Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through artery and capillary, and toward the heart through veins....
. The carotid sinus baroreceptors are innervated by the sinus nerve of Hering, which is a branch of IX (glossopharyngeal nerve
Glossopharyngeal nerve

The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves . It exits the brainstem out from the sides of the upper Medulla oblongata, just rostral to the vagus nerve....
). The glossopharyngeal nerve synapses in the nucleus tractus solitarius (NTS)
Solitary nucleus

The solitary nucleus and tract are structures in the brainstem that carry and receive visceral sensation and taste from the facial nerve , glossopharyngeal nerve and vagus nerve cranial nerves....
 located in the medulla of the brainstem.






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In human anatomy
Human anatomy

Human anatomy, which, with physiology and biochemistry, is a complementary basic medical science is primarily the scientific study of the morphology of the adult human body....
, the carotid sinus is a localized dilation of the internal carotid artery
Internal carotid artery

In human anatomy, the internal carotid artery is a major artery of the head and neck that helps supply blood to the brain....
 at its origin, the common carotid artery
Common carotid artery

In human anatomy, the common carotid artery is an artery that supplies the head and neck with oxygenated blood; it divides in the neck to form the external carotid artery and internal carotid artery....
 bifurcation
Bifurcation

Bifurcation means the splitting of a main body into two parts.Bifurcation or Bifurcated may refer to:*Bifurcation , the division of issues in a trial for example the division of a page into two parts....
.

Functions

It contains numerous baroreceptors, which function as a "sampling area" for many homeostatic
Homeostasis

Homeostasis is the property of a system, either open system or closed system, that regulates its internal environment and tends to maintain a stable, constant condition....
 mechanisms for maintaining blood pressure
Blood pressure

Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through artery and capillary, and toward the heart through veins....
. The carotid sinus baroreceptors are innervated by the sinus nerve of Hering, which is a branch of IX (glossopharyngeal nerve
Glossopharyngeal nerve

The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves . It exits the brainstem out from the sides of the upper Medulla oblongata, just rostral to the vagus nerve....
). The glossopharyngeal nerve synapses in the nucleus tractus solitarius (NTS)
Solitary nucleus

The solitary nucleus and tract are structures in the brainstem that carry and receive visceral sensation and taste from the facial nerve , glossopharyngeal nerve and vagus nerve cranial nerves....
 located in the medulla 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 X (vagus nerve
Vagus nerve

The vagus nerve is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem and extends, through the jugular foramen, down below the head , to the neck, chest and abdomen, where it contributes to the innervation of the viscera....
) and travels to the NTS.

Disease of the carotid sinus

The carotid sinus often has atherosclerotic plaques because of disturbed hemodynamics
Hemodynamics

Hemodynamics, meaning literally "blood movement", is the study of blood flow or the circulation.All animal cells require oxygen for the conversion of carbohydrates, fats and proteins into carbon dioxide , water and energy in a process known as aerobic respiration....
 (low wall shear stress, flow reversal/recirculation). Since these plaques, if large and unstable, predispose to ischemic stroke
Stroke

A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
s and transient ischemic attack
Transient ischemic attack

A transient ischemic attack is caused by the changes in the blood supply to a particular area of the brain, resulting in brief neurologic dysfunction that persists, by definition, for less than 24 hours; if symptoms persist then it is categorized as a stroke....
s, carotid endarterectomies
Carotid endarterectomy

Carotid endarterectomy is a surgery procedure used to prevent stroke, by correcting carotid stenosis in the carotid artery. Endarterectomy is the removal of material on the inside of an artery....
 are frequently done for prophylaxis
Prophylaxis

Prophylaxis is any medical or public health procedure whose purpose is to prevent, rather than treat or cure a disease. Roughly, prophylactic measures are divided between primary prophylaxis and secondary prophylaxis ....
.

The carotid sinus can be oversensitive to manual stimulation, a condition known as carotid sinus hypersensitivity, carotid sinus syndrome or carotid sinus syncope, in which manual stimulation causes large changes in heart rate
Heart rate

Heart rate is a measure of the number of heart beats per minute . The average resting human heart rate is about 70 bpm for adult males and 75 bpm for adult females....
 and/or blood pressure
Blood pressure

Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through artery and capillary, and toward the heart through veins....
.

Carotid sinus massage

Massage
Massage

Massage is the practice of soft tissue manipulation with physical, functional, and in some cases psychological purposes and goals. The word comes from the French language massage "friction of kneading," or from Arabic massa meaning "to touch, feel or handle" or from Latin massa meaning "mass, dough"....
 of the carotid sinus, carotid sinus massage is used to diagnose carotid sinus syncope and is sometimes useful for differentiating supraventricular tachycardia
Supraventricular tachycardia

A supraventricular tachycardia is a tachycardia of the heart in which the origin of the electrical signal is either the atrium or the AV node....
 (SVT) from ventricular tachycardia
Ventricular tachycardia

Ventricular tachycardia is a tachycardia, or fast heart rhythm that originates in one of the left ventricle of the heart. This is a potentially life-threatening Cardiac arrhythmia because it may lead to ventricular fibrillation and sudden cardiac death....
. It, like the valsalva maneuver
Valsalva maneuver

The Valsalva maneuver is performed by forcibly exhaling against a closed airway. Variations of the maneuver can be used either in medicine, as a test of cardiac function and autonomic nervous system of the heart or to "clear" the ears and Aerosinusitis when ambient pressure changes, as in diving or aviation....
, is a therapy for SVT. It is less effective than pharmaceutical management of SVT with verapamil
Verapamil

Verapamil is an L-type calcium channel blocker of the phenylalkylamine class. It has been used in the treatment of hypertension, angina pectoris, cardiac arrhythmia, and most recently, cluster headaches....
 or adenosine
Adenosine

Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule moiety via a ?-N9-glycosidic bond....
 though is still the prefered first-line of treatment in a hemodynamically stable patient

Carotid sinus reflex death

Carotid sinus reflex death is a disputed mechanism of death
Death

Death is the permanent termination of the biological functions that define a life organism. It refers to both a particular event and to the condition that results thereby....
 in which manual stimulation of the carotid sinus allegedly causes strong vagus nerve
Vagus nerve

The vagus nerve is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem and extends, through the jugular foramen, down below the head , to the neck, chest and abdomen, where it contributes to the innervation of the viscera....
 impulses leading to terminal cardiac arrest
Cardiac arrest

A cardiac arrest, also known as cardiopulmonary arrest or circulatory arrest, is the abrupt cessation of normal circulation of the blood due to failure of the heart to contract effectively during Systole ....
. Carotid sinus reflex death has been pointed out as a possible cause of death in cases of strangulation
Strangling

Strangling is compression of the neck that leads to unconsciousness or death by causing an increasingly hypoxia state in the brain. Fatal strangling typically occurs in cases of violence, accidents, and as the mechanism of suicide in hangings....
 and hanging
Hanging

Hanging is the lethal suspension of a person by a ligature. The Oxford English Dictionary states that hanging in this sense is "specifically to put to death by suspension by the neck", although it formerly also referred to crucifixion and death by impalement in which the body would remain "hanging"....
, but such deductions remain controversial. Studies have however suggested that the carotid sinus reflex can be a contributing factor in other mechanisms of death by reducing blood pressure
Blood pressure

Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through artery and capillary, and toward the heart through veins....
 and heart rate
Heart rate

Heart rate is a measure of the number of heart beats per minute . The average resting human heart rate is about 70 bpm for adult males and 75 bpm for adult females....
, especially in the elderly or in people suffering from carotid sinus hypersensitivity. A carotid massage can also possibly dislodge a thrombus, or some plaque. This could lead to any number of life threatening effects, including, but not limited to pulmonary embolism
Pulmonary embolism

Pulmonary embolism is a blockage of the pulmonary artery or one of its branches, usually occurring when a deep vein thrombosis becomes dislodged from its site of formation and travels, or embolism, to the pulmonary artery blood supply of one of the lungs....
, heart attack, and stroke
Stroke

A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
. All of these are potentially lethal.

See also

  • Carotid body
    Carotid body

    The carotid body is a small cluster of chemoreceptors and supporting cells located near the fork of the carotid artery .The carotid body detects changes in the composition of arterial blood flowing through it, mainly the partial pressure of oxygen, but also of carbon dioxide....
  • Baroreflex
    Baroreflex

    In cardiovascular physiology, the baroreflex or baroreceptor reflex is one of the body's homeostasis mechanisms for maintaining blood pressure....


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