Carotid sinus
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2008-04-17T18:15:25Z
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{{Infobox Anatomy |
Name = {{PAGENAME}} |
Latin = sinus caroticus |
GraySubject = |
GrayPage = |
Image = Gray513.png |
Caption = Arteries of the neck. The '''carotid sinus''' is at the origin of the [[internal carotid artery]]. |
Image2 = |
Caption2 = |
Precursor = |
System = |
Artery = |
Vein = |
Nerve = [[branch of glossopharyngeal nerve to carotid sinus]] |
Lymph = |
MeshName = Carotid+Sinus |
MeshNumber = A07.231.114.186.456 |
DorlandsPre = s_12 |
DorlandsSuf = 12738619 |
}}
In [[human anatomy]], the '''carotid sinus''' is a localized dilation of the [[internal carotid artery]] at its origin, the [[common carotid artery]] [[bifurcation]].
==Functions==
It contains numerous [[baroreceptors]], which function as a "sampling area" for many [[homeostasis|homeostatic]] mechanisms for maintaining [[blood pressure]]. The carotid sinus baroreceptors are innervated by the sinus nerve of Hering, which is a branch of IX ([[glossopharyngeal nerve]]). The glossopharyngeal nerve synapses in the [[Solitary nucleus|nucleus tractus solitarius (NTS)]] located in the medulla of the brainstem. The NTS modulates the activity of sympathetic and parasympathetic (vagal) neurons in the medulla. These neurons then regulate the autonomic control of the heart and blood vessels. The aortic arch baroreceptors are innervated by the aortic nerve, which combines with X ([[vagus nerve]]) and travels to the NTS.
==Disease of the carotid sinus==<!-- This section is linked from [[Swimming]] -->
The carotid sinus often has [[atherosclerotic plaque]]s because of disturbed [[hemodynamics]] (low [[wall shear stress]], flow reversal/recirculation).<ref>Glagov S, Zarins C, Giddens DP, Ku DN. Hemodynamics and atherosclerosis. Insights and perspectives gained from studies of human arteries. biod degradable Arch Pathol Lab Med. 1988 Oct;112(10):1018-31. PMID 3052352</ref> Since these plaques, if large and unstable, predispose to [[Stroke#Ischemic stroke 2|ischemic stroke]]s and [[transient ischemic attack]]s, [[carotid endarterectomy|carotid endarterectomies]] are frequently done for [[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]] and/or [[blood pressure]].
==Carotid sinus massage==
[[Massage]] of the carotid sinus, '''carotid sinus massage''' is used to diagnose carotid sinus syncope and is sometimes useful for differentiating [[supraventricular tachycardia]] (SVT) from [[ventricular tachycardia]]. It, like the [[valsalva maneuver]], is a therapy for SVT.<ref>Lim SH, Anantharaman V, Teo WS, Goh PP, Tan AT. Comparison of treatment of supraventricular tachycardia by Valsalva maneuver and carotid sinus massage. Ann Emerg Med. 1998 Jan;31(1):30-5. PMID 9437338</ref> However, it is less effective than pharmaceutical management of SVT with [[verapamil]] or [[adenosine]].<ref>Ballo P, Bernabo D, Faraguti SA. Heart rate is a predictor of success in the treatment of adults with symptomatic paroxysmal supraventricular tachycardia. Eur Heart J. 2004 Aug;25(15):1310-7. PMID 15288158</ref>
==Carotid sinus reflex death==
'''Carotid sinus reflex death''' is a disputed mechanism of [[death]] in which manual stimulation of the carotid sinus allegedly causes strong [[vagus nerve]] impulses leading to terminal [[cardiac arrest]]. Carotid sinus reflex death has been pointed out as a possible cause of death in cases of [[strangling|strangulation]] and [[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]] and [[heart rate]], 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]], [[heart attack]], and [[stroke]]. All of these are potentially lethal. <ref>Passig, K. [http://www.datenschlag.org/howto/atem/english/csr.html Carotid sinus reflex death - a theory and its history.] URL last accessed [[February 28]] [[2006]].</ref>
== See also ==
* [[Carotid body]]
* [[Baroreflex]]
==References==
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==External links==
* {{MUNAnatomy|head/cbv}}
* {{NormanAnatomy|lesson5}} ({{NormanAnatomyFig|livingneck}})
{{Arteries of head and neck}}
[[Category:Arteries]]
[[Category:Head and neck]]
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