The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the

atrioventricular valves A heart valve is a one-way valve that allows blood to flow in one direction through the chambers of the heart. Four valves are usually present in a mammalian heart and together they determine the pathway of blood flow through the heart. A heart v ...

(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 or flaps and lies between the left atrium and the left ventricle of the heart. The heart valves are all one-w ...

and

tricuspid 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 ven ...

valves) via the

chordae tendineae The chordae tendineae (tendinous cords), colloquially known as the heart strings, are inelastic cords of fibrous connective tissue that connect the papillary muscles to the tricuspid valve and the mitral valve in the heart. Structure The chordae ...

and

contract A contract is a legally enforceable agreement between two or more parties that creates, defines, and governs mutual rights and obligations between them. A contract typically involves the transfer of goods, services, money, or a promise to tran ...

to prevent inversion or

prolapse In medicine, prolapse is a condition in which organs fall down or slip out of place. It is used for organs protruding through the vagina, rectum, or for the misalignment of the valves of the heart. A spinal disc herniation is also sometimes call ...

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. The term originates, via New Latin, from Ancient Greek (''sustolē''), from (''sustéllein'' 'to contract'; from ''sun ...

(or ventricular contraction). The papillary muscles constitute about 10% of the total heart mass.

Structure

There are five total papillary muscles in the heart; three in the right ventricle and two in the left. The anterior, posterior, and septal papillary muscles of the right ventricle each attach via

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

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 or flaps and lies between the left atrium and the left ventricle of the heart. The heart valves are all one-w ...

.Netter's Atlas of Human Anatomy, plates 216B and 217A

Blood supply

The mitral valve papillary muscles in the left ventricle are called the anterolateral and posteromedial muscles. * Anterolateral muscle blood supply:

left anterior descending artery The left anterior descending artery (also LAD, anterior interventricular branch of left coronary artery, or anterior descending branch) is a branch of the left coronary artery. Blockage of this artery is often called the ''widow-maker infarction' ...

- diagonal branch (LAD) and

left circumflex artery The circumflex branch of left coronary artery, or left circumflex artery or circumflex artery, is a branch of the left coronary artery. Description The left circumflex artery follows the left part of the coronary sulcus, running first to the ...

obtuse marginal branch The left marginal artery (or obtuse marginal artery) is a branch of the circumflex artery, originating at the left atrioventricular sulcus, traveling along the left margin of heart towards the apex of the heart. See also * Right marginal branch ...

(LCX) * Posteromedial muscle blood supply:

right coronary artery In the blood supply of the heart, the right coronary artery (RCA) is an artery originating above the right cusp of the aortic valve, at the right aortic sinus in the heart. It travels down the right coronary sulcus, towards the crux of the hear ...

posterior interventricular artery In the coronary circulation, the posterior interventricular artery (PIV, PIA, or PIVA), most often called the posterior descending artery (PDA), is an artery running in the posterior interventricular sulcus to the apex of the heart where it meets ...

(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 The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following ...

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 infarct A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may tra ...

, 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 wi ...

. Both 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.

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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