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Papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. They are attached by fine strands of tendon to the valves between the atria and ventricles, and they contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction). There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle.
| Characteristics | Values |
|---|---|
| Location | Ventricles of the heart |
| Description | Thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles |
| Number | Five in total; three in the right ventricle and two in the left ventricle |
| Blood supply | The left coronary artery, the right coronary artery, or the circumflex artery |
| Function | Prevent inversion or prolapse of the atrioventricular valves on systole (or ventricular contraction) |
| Related conditions | Barlow's disease, myocardial infarction, ischemia, blunt chest trauma |
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What You'll Learn
Papillary muscle development
Papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. They are located in the ventricles of the heart and attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae. There are five papillary muscles in the heart: three in the right ventricle (anterior, posterior, and septal) and two in the left ventricle (anterolateral and posteromedial).
The papillary muscles play a crucial role in maintaining proper cardiac valvular function. They contract shortly before ventricular systole and maintain tension throughout, preventing the backward flow of blood into the atrial cavities (regurgitation) by bracing the atrioventricular valves against prolapse. The contraction of the papillary muscles is essential for the closure of the atrioventricular valves, ensuring proper blood flow through the heart.
The development of the papillary muscles begins early in fetal cardiac development. The aortic leaflet of the mitral valve forms from atrioventricular cushion tissue between the anterior and posterior sections of the ridges at approximately week seven. From weeks eight to ten, the papillary muscles emerge from the anterior and posterior segments of the ridge, with increased mobility and the emergence of valve leaflets and precursors to chordae tendinae noted at approximately week twelve. The development of the papillary muscles becomes further refined between weeks fourteen to nineteen, with valve completion and the development of the chordae tendinae.
The blood supply to the papillary muscles varies. The blood supply to the left anterolateral papillary muscles typically comes from branches of the left coronary artery, while the left posteromedial papillary muscles receive blood from the right coronary artery in most cases. However, in some instances, the posteromedial papillary muscles may receive blood from branches of the left circumflex artery. The blood supply to the anterior papillary muscle of the right ventricle usually originates from branches of the left and right coronary arteries, although anatomical variations exist, with some cases deriving blood supply solely from the left coronary artery.
The lymphatic supply of the papillary muscles is formed from lymphatic plexuses with varying sizes of lymphatic vessels. The papillary muscles receive innervation from the cardiac plexus fibres, which regulate the pacemaker of the heart and the spread of impulses into the ventricles.
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Blood supply to papillary muscles
Papillary muscles are endocardial structures that can harbour arrhythmic substrates in structural heart disease and an apparently normal heart. They are a group of two to three "papillae" that originate from the distal third of the ventricular wall. The left cardiac ventricle contains two papillary muscles: the anterolateral and posteromedial. The right ventricle contains three: the anterior, posterior, and septal.
The blood supply to the papillary muscles is segmental in distribution, and reaches the muscle from large penetrating branches originating from epicardial vessels located radially outward from the muscle. The tip, mid-portion, and base generally receive their vascular supply from separate tributaries with a radial arrangement. The anterolateral papillary muscle is irrigated by the first obtuse marginal branch of the circumflex artery and the first diagonal branch of the anterior descending artery. The blood supply to the anterolateral papillary muscle derives from the left coronary artery. The left anterior descending and the diagonal or a marginal branch of the circumflex artery also supply blood to the anterolateral papillary muscle.
The posteromedial papillary muscle is irrigated only by the posterior descending artery, a branch of the right descending coronary artery in 90% of cases, and by the circumflex artery in the remaining 10%. The blood supply to the posteromedial papillary muscle most commonly derives from the right coronary artery. In some cases, the posteromedial papillary muscle receives blood supply from branches of the left circumflex artery. The left circumflex or right coronary artery provides the blood supply to the posteromedial papillary muscle, depending on dominance.
The blood supply to the anterior papillary muscle of the right ventricle most commonly originates from vessels branching from the left and right coronary arteries. In some cases, the blood supply originates only from the left coronary artery. The posterior papillary muscle was opacified in sixteen patients, eleven from the right coronary artery and five from one obtuse marginal branch. In sixty-three percent of patients, the papillary muscle was perfused by one vessel, while in thirty-seven percent, it was perfused by two vessels.
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Papillary muscle anatomy
Papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. They are attached by fine strands of tendon to the valves between the atria and ventricles, known as the atrioventricular valves or the mitral and tricuspid valves. The mitral valve is located in the left ventricle, and the tricuspid valve is located in the right ventricle.
The papillary muscles are responsible for maintaining tension during ventricular systole, which prevents regurgitation, or the backward flow of ventricular blood into the atrial cavities. They contract to prevent inversion or prolapse of the valves on systole, or ventricular contraction. The contraction of the papillary muscles is essential to prevent the longitudinal shortening of the left ventricle, which would result in a prolapse of the leaflets.
There are five papillary muscles in the heart, with three in the right ventricle and two in the left ventricle. The right ventricle contains the anterior, posterior, and septal papillary muscles. The anterior is the largest and arises from the anterior wall, while the posterior arises from the inferior wall. The septal is the smallest and arises from the interventricular septum. The left ventricle contains the anterolateral and posteromedial papillary muscles, which arise from the sternocostal wall and the diaphragmatic wall of the ventricle, respectively.
The blood supply to the papillary muscles varies. The anterior papillary muscle of the right ventricle typically receives blood from vessels branching from the left and right coronary arteries, while the anterolateral papillary muscle of the left ventricle receives blood from the left coronary artery and its branches. The posteromedial papillary muscle of the left ventricle is usually supplied by the right coronary artery, although it can sometimes receive blood from branches of the left circumflex artery.
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Papillary muscle dysfunction
The papillary muscles are endocardial structures that play a vital role in maintaining normal mitral valve function. They originate from the distal third of the ventricular wall, with two organised groups labelled based on their position relative to the mitral commissures: the anterolateral papillary muscle and the posteromedial papillary muscle. The anterolateral muscle has a single body and receives a dual blood supply, while the posteromedial muscle typically has two bodies and is supplied solely by the posterior descending coronary artery.
- Ischemia or infarction: The posteromedial papillary muscle is more prone to injury from myocardial infarction due to its single blood supply. This can lead to rupture or dysfunction of the muscle.
- Ventricular dilatation: Chronic or acute ventricular dilatation can cause papillary muscle displacement, resulting in mitral regurgitation.
- Rupture: Rupture of a papillary muscle is a rare but potentially fatal complication, often occurring after myocardial infarction or due to infective endocarditis.
- Inflammatory disease: Inflammation of a papillary muscle can lead to dysfunction and mitral regurgitation.
- Conduction disturbances: Interventricular conduction disturbances can impact the normal electrical impulses that regulate the papillary muscles.
The consequences of papillary muscle dysfunction include mitral regurgitation, where there is severe mitral valve regurgitation, leading to acute life-threatening cardiogenic shock and pulmonary edema. Dysfunction can also result in apical systolic murmurs, with varying characteristics depending on the underlying cause.
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Papillary muscle rupture
The heart contains five papillary muscles originating from the ventricular walls. Three of these—anterior, posterior, and septal—attach to the tricuspid valve, while the other two—anterolateral and posteromedial—connect to the mitral valve. The anterolateral papillary muscle receives a dual blood supply, while the posteromedial muscle is supplied solely by the posterior descending coronary artery. Due to this single blood supply, the posteromedial papillary muscle is more likely to rupture following a myocardial infarction.
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Frequently asked questions
Papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles.
Papillary muscles are located in the ventricles of the heart.
Papillary muscles attach to the cusps of the atrioventricular valves and contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction).
There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle.
Papillary muscle rupture can be caused by a myocardial infarction. Complications may lead to worsening of mitral regurgitation.
