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The papillary muscles are pillar-like muscles located in the ventricles of the heart. They play a crucial role in maintaining proper cardiac function by preventing the backward flow of blood from the ventricles into the atrial cavities. These muscles contract during ventricular systole, maintaining tension and bracing the valves to prevent prolapse. The rupture or dysfunction of papillary muscles can have severe consequences, and their structure and function have been studied extensively, with historical mentions dating back to the 16th century.
| Characteristics | Values |
|---|---|
| Location | Cavity of the ventricles |
| Origin | Inner walls of the left and right ventricles |
| Attachment | Cusps of the atrioventricular valves (mitral and tricuspid valves) via chordae tendineae |
| Function | Prevent inversion or prolapse of the valves during ventricular contraction |
| Number | Five in total (three in the right ventricle and two in the left ventricle) |
| Blood Supply | Dependent on the specific papillary muscle and its position; can derive from the left coronary artery, right coronary artery, or branches of the left circumflex artery |
| Innervation | Cardiac plexus fibers |
| Dysfunction | Can lead to mitral regurgitation and potentially fatal complications |
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What You'll Learn
The papillary muscles are located in the heart's ventricles
The papillary muscles are pillar-like muscles located within the cavity of the heart's ventricles, attached to their walls. There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. The right ventricle contains the anterior, posterior, and septal papillary muscles, while the left ventricle contains the anterolateral and posteromedial papillary muscles.
The papillary muscles play a crucial role in maintaining proper cardiac valvular function. They attach to the cusps of the atrioventricular valves, also known as the mitral and tricuspid valves, via the chordae tendineae. This connection prevents the inversion or prolapse of these valves during systole, or ventricular contraction. The contraction of the papillary muscles is essential for preventing regurgitation, the backward flow of ventricular blood into the atrial cavities. By bracing the atrioventricular valves, the papillary muscles prevent prolapse, which can be caused by the high pressure in the ventricles.
The papillary muscles of both the right and left ventricles begin to contract shortly before ventricular systole and maintain tension throughout. This contraction is regulated by the cardiac plexus fibres, which innervate and control the heart's pacemaker, the SA node. The AV bundles carrying impulses from the AV node cross the fibrous ring to enter the interventricular septum, dividing into the right and left bundles of His. These bundles then further subdivide into thin fibres called Purkinje fibres at the base of the papillary muscles, allowing the impulses to spread into the ventricles and initiate contraction.
The blood supply to the papillary muscles is an important consideration. The blood supply to the left anterolateral papillary muscle comes from branches of the left coronary artery, while the left posteromedial papillary muscle typically receives blood from the right coronary artery. However, in some cases, the posteromedial papillary muscle may receive blood supply from branches of the left circumflex artery. The single system of blood supply to the posteromedial papillary muscle makes it particularly vulnerable to injury from myocardial infarction.
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They prevent the inversion of atrioventricular valves
The papillary muscles are pillar-like muscles located within the cavity of the ventricles, attached to their walls. There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. The left ventricle contains the anterolateral and posteromedial papillary muscles, which attach to the mitral valve via chordae tendineae. The right ventricle contains the anterior, posterior, and septal papillary muscles, which attach to the tricuspid valve via chordae tendineae.
The papillary muscles play a crucial role in maintaining proper cardiac valvular function, specifically by preventing the inversion of atrioventricular valves. During ventricular systole, or contraction of the ventricles, the papillary muscles contract and maintain tension to brace the atrioventricular valves against prolapse, or being forced back into the atria. This prevents regurgitation, which is the backward flow of blood from the ventricles into the atrial cavities.
The contraction of the papillary muscles is essential for the proper functioning of the atrioventricular valves. Without this contraction, the longitudinal shortening of the left ventricle (LV) would result in a prolapse of the valve leaflets. The papillary muscles also contribute to the redirection of blood flow during systole, bulging into the LV cavity and guiding the flow toward the aortic valve, forming part of the LV outflow tract.
The papillary muscles receive their blood supply from various arteries, depending on their location. The anterolateral papillary muscle is supplied by the left anterior descending artery and its diagonal branch, as well as the left circumflex artery and its obtuse marginal branch. The posteromedial papillary muscle is typically supplied by the right coronary artery, although in some cases, it may receive blood from branches of the left circumflex artery.
Overall, the papillary muscles play a vital role in maintaining cardiac health and ensuring the proper functioning of the atrioventricular valves by preventing their inversion during ventricular contraction.
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There are five papillary muscles in the heart
The heart has five papillary muscles, three in the right ventricle and two in the left ventricle. These muscles are located within the cavity of the ventricles, attached to their walls. They are integral to the proper cardiac valvular function. The papillary muscles of the heart are pillar-like muscles and play a crucial role in maintaining cardiac health.
The left cardiac ventricle contains two papillary muscles: the anterolateral and posteromedial. The anterolateral muscle arises from the sternocostal wall, while the posteromedial muscle usually has two bodies or heads. The blood supply to the left anterolateral papillary muscles comes from the branches of the left coronary artery, while the left posteromedial papillary muscles derive their blood supply from the right coronary artery.
The papillary muscles in the left ventricle are essential for mitral valve function. The mitral valve resides in the left atrio-ventricular groove, and the chordae tendinae are connected to the ventricle via these muscles. Each papillary muscle provides chordae to both leaflets, ensuring the proper functioning of the mitral valve.
The right ventricle contains three papillary muscles: the anterior, posterior, and septal papillary muscles. These muscles attach to the tricuspid valve leaflets via the chordae tendinae. The papillary muscles in the right ventricle play a similar role to those in the left ventricle, ensuring proper cardiac function.
The papillary muscles of the heart contract shortly before ventricular systole and maintain tension throughout. This contraction prevents the backward flow of blood from the ventricles into the atrial cavities, known as regurgitation. The proper functioning of the papillary muscles is crucial for maintaining cardiac health and ensuring efficient blood flow throughout the body.
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Blunt trauma can lead to papillary muscle rupture
The heart contains five papillary muscles that originate from the ventricular walls. These muscles are attached to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae. They contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction). Papillary muscles play an integral role in proper cardiac valvular function.
Papillary muscle rupture is a rare complication, estimated to occur in 1% to 5% of patients with acute myocardial infarction. Myocardial infarction is the most common cause of papillary muscle rupture. However, other causes include trauma, syphilis, periarteritis nodosa, vegetative valvulitis, myocardial abscess, iatrogenic injury, and cocaine use. Blunt chest trauma is a rare cause of papillary muscle rupture, resulting from the sudden deceleration or compression of the heart.
Blunt thoracic trauma (BTT) is a primary cause of morbidity, mortality, hospitalization, and disability in the United States and contributes to over a quarter of all trauma-related deaths. BTT can result in various cardiac injuries, ranging from minor contusions to more severe pathologies such as cardiac rupture, pericardial rupture, cardiac herniation, valvular injury, myocardial infarction, or arrhythmia. While rare, BTT-associated mitral valve injury, pericardial rupture, and cardiac herniation are independently associated with high mortality rates.
Mitral regurgitation due to papillary muscle rupture after blunt chest trauma is uncommon. However, sudden-onset severe mitral regurgitation may lead to death due to heart failure if surgical repair is delayed. Diagnosis of papillary muscle rupture relies primarily on echocardiography, which may reveal ruptured or dysfunctional papillary muscles, severe mitral regurgitation, and signs of hemodynamic instability. Management requires urgent stabilization, followed by prompt surgical intervention, typically mitral valve repair or replacement. Early detection and rapid intervention improve survival outcomes, but long-term prognosis depends on the extent of left ventricular damage and overall patient health.
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Papillary muscle dysfunction can be caused by ischemia
The heart contains five papillary muscles that originate from the ventricular walls. These muscles are pillar-like and are located within the cavity of the ventricles, attached to their walls. They play an integral role in proper cardiac valvular function, preventing the backflow of blood into the heart's atrial cavities.
Myocardial infarction may cause papillary muscle dysfunction when the blood supply is provided by one rather than two vessels, as is more frequently the case with the posterior rather than the anterior papillary muscle. In a study of 16 patients, 10 (63%) had a single-vessel blood supply to the papillary muscle, while 6 (37%) had a double-vessel supply. Of these, 10 patients (71%) with old inferior myocardial infarction and mitral regurgitation had a single blood supply, indicating that a single blood supply may be a risk factor for papillary muscle dysfunction and mitral regurgitation following myocardial infarction.
Coronary artery spasm can also lead to papillary muscle dysfunction and ischemic mitral regurgitation. The transient inadequacy of blood supply to the papillary muscles during acute coronary syndrome can cause a transient murmur of papillary muscle dysfunction.
In summary, papillary muscle dysfunction can be caused by ischemia, or inadequate blood supply to the papillary muscles, leading to blood regurgitation and potential heart failure. The posteromedial papillary muscle is particularly vulnerable to ischemia due to its single blood supply. Myocardial infarction and coronary artery spasm can also lead to papillary muscle dysfunction, with the former more likely to occur when there is a single blood supply.
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Frequently asked questions
The papillary muscles are pillar-like muscles located in the ventricles of the heart. There are five in total, with three in the right ventricle and two in the left ventricle.
The papillary muscles attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae. They contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction).
Papillary muscle rupture can be caused by myocardial infarction, ischemia, or blunt chest trauma resulting from the sudden deceleration or compression of the heart.
Papillary muscle rupture can lead to complications such as worsening mitral regurgitation. Immediate treatment is required as rupture can be fatal.
