Cardiac skeleton: Difference between revisions
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==General form and anatomy== |
==General form and anatomy== |
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The cardiac skeleton consists of four dense bands of tough elastic tissue that encircle the bases of the pulmonary trunk, aorta, and heart valves.<ref>''Martini Anatomy and Physiology, 5th ed.'' |
The cardiac skeleton consists of four dense bands of tough elastic tissue that encircle the bases of the pulmonary trunk, aorta, and heart valves.<ref>''Martini Anatomy and Physiology, 5th ed.'' |
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</ref> While not a "true" [[skeleton]], it does provide structure and support for the heart, as well as isolating the atria from the ventricles. This |
</ref> While not a "true" [[skeleton]], it does provide structure and support for the heart, as well as isolating the atria from the ventricles. In youth, this collagen structure is free of calcium adhesions and is quite flexible. The aging heart and vascular tree accumulates calcium to the detriment of compliance and defines itself more clearly by [[Calcium Score]]. This accumulation contributes to the [[AV node]] and [[AV bundle]] delay of the depolarisation wave such that the atria can contract and assist in ventricular filling before the ventricles themselves depolarise and contract (the AV bundle is the only part of the conduction system that passes from the atria to the ventricles in a normal heart). It also allows the valves (bicuspid, tricuspid, semilunar) to keep open by giving them structural support.<ref name="Gray">{{Cite book|last=Gray|first=Henry|title=Gray's Anatomy|edition=1918|year=1918|publisher=Longmans|location=London|chapter=The Heart|isbn=613-0-24743-5}}</ref> |
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==Fibrous rings== |
==Fibrous rings== |
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Revision as of 01:02, 10 August 2012
The cardiac skeleton, sometimes called the fibrous skeleton of the heart, is the structure of dense connective tissue in the heart that separates the atria from the ventricles. The cardiac skeleton establishes electrically impermeable boundaries to autonomic influence within the heart. The anchored Collagen framework of four valves in a plane has the unique property of being electrically inert. In normal anatomy the AV node is the only electrical conduit from the atria to the ventricles through the cardiac skeleton.
General form and anatomy
The cardiac skeleton consists of four dense bands of tough elastic tissue that encircle the bases of the pulmonary trunk, aorta, and heart valves.[1] While not a "true" skeleton, it does provide structure and support for the heart, as well as isolating the atria from the ventricles. In youth, this collagen structure is free of calcium adhesions and is quite flexible. The aging heart and vascular tree accumulates calcium to the detriment of compliance and defines itself more clearly by Calcium Score. This accumulation contributes to the AV node and AV bundle delay of the depolarisation wave such that the atria can contract and assist in ventricular filling before the ventricles themselves depolarise and contract (the AV bundle is the only part of the conduction system that passes from the atria to the ventricles in a normal heart). It also allows the valves (bicuspid, tricuspid, semilunar) to keep open by giving them structural support.[2]
Fibrous rings
| Fibrous rings of heart | |
|---|---|
 Transverse section of the heart showing the fibrous rings surrounding the valves | |
| Details | |
| Identifiers | |
| Latin | anulus fibrosus dexter cordis, anulus fibrosus sinister cordis |
| Anatomical terminology | |
| Fibrous trigone | |
|---|---|
| Details | |
| Identifiers | |
| Latin | trigonum fibrosum dextrum cordis, trigonum fibrosum sinistrum cordis, trigona fibrosa |
| Anatomical terminology | |
The right and left fibrous rings of heart (anulus fibrosus cordis) surround the atrioventricular and arterial orifices, and are decidedly stronger upon the left than on the right side of the heart. Physiologically, this is readily appreciated in light of the pressure differential between the right and left circuits. The right fibrous ring is known as the anulus fibrosus dexter cordis, and the left is known as the anulus fibrosus sinister cordis.[2]
The upper chambers (atria) and lower (ventricles) are divided by the unique properties of Collagen. The valve rings, central body and skeleton of the heart consisting of collagen are impermeable to electrical propagation. The only channel allowed (barring accessory/rare preexcitation channels) through this collagen barrier is represented by a sinus that opens up to the Atrioventricular node and exits to the Bundle of His. The muscle origins/insertions of many of the cardiomyocytes are anchored to opposite sides of the valve rings.[2]
The atrioventricular rings serve for the attachment of the muscular fibers of the atria and ventricles, and for the attachment of the bicuspid and tricuspid valves.[2]
The left atrioventricular ring is closely connected, by its right margin, with the aortic arterial ring; between these and the right atrioventricular ring is a triangular mass of fibrous tissue, the Fibrous trigone, which represents the os cordis seen in the heart of some of the larger animals, as the ox and elephant.[2]
Lastly, there is the tendinous band, already referred to, the posterior surface of the conus arteriosus.[2]
The fibrous rings surrounding the arterial orifices serve for the attachment of the great vessels and semilunar valves, they are known as The aortic annulus.[2]
Each ring receives, by its ventricular margin, the attachment of some of the muscular fibers of the ventricles; its opposite margin presents three deep semicircular notches, to which the middle coat of the artery is firmly fixed.[2]
The attachment of the artery to its fibrous ring is strengthened by the external coat and serous membrane externally, and by the endocardium internally.[2]
From the margins of the semicircular notches the fibrous structure of the ring is continued into the segments of the valves.[2]
The middle coat of the artery in this situation is thin, and the vessel is dilated to form the sinuses of the aorta and pulmonary artery.[2]
See also
References
External links
- . GPnotebook https://www.gpnotebook.co.uk/simplepage.cfm?ID=-1026555847.
{{cite web}}: Missing or empty|title=(help) - Description at cwc.net
- Diagram of skeleton at vanderbilt.edu
- Another illustration at vanderbilt.edu
- Overview at vanderbilt.edu
- . GPnotebook https://www.gpnotebook.co.uk/simplepage.cfm?ID=261750843.
{{cite web}}: Missing or empty|title=(help), – "left fibrous trigone" - . GPnotebook https://www.gpnotebook.co.uk/simplepage.cfm?ID=798621756.
{{cite web}}: Missing or empty|title=(help), – "right fibrous trigone" - Histology (see slide #96)
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This article incorporates text in the public domain from page 536 of the 20th edition of Gray's Anatomy (1918)