The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the

mitral The mitral valve ( ), also known as the bicuspid valve or left atrioventricular valve, is one of the four heart valves. It has two Cusps of heart valves, cusps or flaps and lies between the atrium (heart), left atrium and the ventricle (heart), ...

and tricuspid valves) via the chordae tendineae and

contract A contract is an agreement that specifies certain legally enforceable rights and obligations pertaining to two or more parties. A contract typically involves consent to transfer of goods, services, money, or promise to transfer any of thos ...

to prevent inversion or prolapse of these valves on

systole Systole ( ) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. Its contrasting phase is diastole, the relaxed phase of the cardiac cycle when the chambers of the heart are refilling ...

(or ventricular contraction).

Structure

There are five total papillary muscles in the heart; three in the

right ventricle A ventricle is one of two large chambers located toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium (heart), atrium, an adjace ...

and two in the left ventricle. The anterior, posterior, and septal papillary muscles of the right ventricle each attach via chordae tendineae to the

tricuspid valve The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, at the superior portion of the right ventricle. The function of the valve is to allow blood to flow from the right atrium to the right vent ...

. The anterolateral and posteromedial papillary muscles of the left ventricle attach via chordae tendineae to the

mitral valve The mitral valve ( ), also known as the bicuspid valve or left atrioventricular valve, is one of the four heart valves. It has two Cusps of heart valves, cusps or flaps and lies between the atrium (heart), left atrium and the ventricle (heart), ...

Blood supply to the left ventricle

The mitral valve papillary muscles in the left ventricle are called the anterolateral and posteromedial muscles. * Anterolateral muscle blood supply: left anterior descending artery - diagonal branch (LAD) and left circumflex artery - obtuse marginal branch (LCX) * Posteromedial muscle blood supply: right coronary artery - posterior interventricular artery (RCA) The posteromedial muscle ruptures more frequently because it only has one source of blood supply, hence RCA occlusion can cause papillary muscle rupture.

Function

The papillary muscles of both the right and left ventricles begin to contract shortly before ventricular systole and maintain tension throughout. This prevents regurgitation—backward flow of ventricular blood into the atrial cavities—by bracing the atrioventricular valves against prolapse—being forced back into the atria by the high pressure in the ventricles.

Clinical significance

Papillary muscle rupture can be caused by a myocardial infarction, and dysfunction can be caused by

ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems ...

. Rarely, blunt chest trauma can be the cause of papillary muscle rupture, resulting from the sudden deceleration or compression of the heart. Complications may lead to worsening of

mitral regurgitation Mitral regurgitation (MR), also known as mitral insufficiency or mitral incompetence, is a form of valvular heart disease in which the mitral valve is insufficient and does not close properly when the heart pumps out blood. Section: Valvular He ...

Additional images

File:Heart short axis view papillary.jpg, Opened chambers of the heart displaying papillary muscles and chordae tendineae File:Gross pathology of papillary muscle infarction.jpg, Papillary muscle infarction File:Muscolopapillare+cordetendinee.jpg, Papillary muscles and chordae tendineae File:Muscolopapillarex.jpg, Papillary muscles and chordae tendineae File:Slide16bek.JPG, Papillary muscles. Deep dissection.

References

External links

* } — "Heart: The Right Atrioventricular (Tricupsid) Valve" (anterior, posterior, septal papillary muscles) * — "Heart: The Left Atrioventricular (Mitral) Valve" (anterior, posterior papillary muscles) * } — "Right atrioventricular bundle branch, anterior view"
Definition of Papillary muscle

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