Define papillary muscles:
Papillary muscles heart are “nipple” like muscle found in ventricular part of the heart, that attach mitral (bicuspid) and tricuspid valves (also known as atrioventricular valves), by chordae tendineae.
The papillary muscles of the heart attach to the cusps of the atrioventricular valves by means of chordae tendineae. So, what is the function of the papillary muscles?
What is the function of papillary muscles?
Papillary muscles function are to preventing each valve (mitral and tricuspid) from prolapse (shrink together) on the period of contraction of the heart (systole period). Contractions of the papillary muscles pulls the chordae tendineae to keep the valves in their normal position.
Papillary muscles are horizontal ridges in the walls of the atrium.
Rupture of the papillary muscles in the left ventricle may result in stopping normal function of the heart and can lead to collapse (shrink of the entire heart). Papillary muscles rupture can be caused by secondary to myocardial infarction. That is the main purpose of it.
Papillary muscles and chordae tendineae:
Firstly, we need to understand that bicuspid (mitral) valve has two cusps by the use of “bi”, and tricuspid valve has 3 cusps by the use of “tri”.
Papillary muscles anatomy, there are 5 heart papillary muscles:
- 2 found in the left ventricle: attach mitral valve papillary muscles
- 3 found in right ventricle: attach tricuspid valve
Let’s start by:
-Left ventricle papillary muscles:
- Anterior-lateral papillary muscle
- Posterior-medial papillary muscle
-Right ventricle papillary muscles:
- Anterior papillary muscle
- Septal papillary muscle
- Posterior papillary muscle
Chordae tendineae and papillary muscles carry the blood circulation inside and outside the heart to the body by the pumping function of the valves. Contraction of the papillary muscles would make the atrioventricular valves to open and filling the ventricular heart chambers with blood coming from the atrium.
Left ventricle where we can find mitral valve papillary muscle has:
- Blood supply of anterior-lateral papillary muscle: left interventricular artery (LIA) or left anterior descending artery (LAD)
His origin is coming from left coronary artery (LCA)
- Blood supply of posterior-medial papillary muscle: left circumflex (LCX)
His origin also coming from left coronary artery (LCA)
Coronary artery anatomy:
- Left coronary artery:
- First is left circumflex (LXA): supply posterior papillary muscle and posterior wall of left ventricle
- Second is left interventricular artery (LIA) or left anterior descending artery (LAD): supply anterior papillary muscle and anterior wall of left ventricle
- Right coronary artery: supply all right of heart (right atrium and right ventricle) and SA, AV nodes
To know: SA node is found in atrium of heart and AV node is found between atrium and ventricle.
- Mitral valve (also called bicuspid valve) is located between left atrium and left ventricle
- Tricuspid valve is located between right atrium and right ventricle
- Aortic valve (also called aortic semilunar valve) is located in the left ventricle
- Pulmonary valve (also called pulmonary semilunar valve) is located in the right ventricle
Location of valves in relation to the sternum:
- Aortic valve: in the second intercostal space right sternal
- Pulmonary valve: in the second intercostal space left sternal
- Mitral (bicuspid) valve: in the apex of the heart
- Tricuspid valve: in the fifth intercostal space left sternal
Pathology can happen to a newborn between pulmonary trunk and aorta is that the ductus arteriosus (or botallo duct) is still open.
-Without oxygen: coming from the body to the vena cava into the right atrium, then goes to the right ventricle from tricuspid valve, then goes to the lung from pulmonary valve to get oxygen and in the final return to the left atrium.
-With oxygen: start from going from left atrium to the left ventricle using mitral valve, then get pumped from the aorta in the left ventricle to all the body.
Sounds of the heart:
We got 4 sounds of the heart:
- S1= Closer of mitral (bicuspid) and tricuspid valve
- S2= Closer of the aortic and pulmonary semilunar valve
- S3= Occur just after S2 when the mitral valve open and allow passive filling of the left ventricle
- S4= Occur just after S1 when the atria chambre of the heart pump blood with force to the left ventricle
Cardiac output = Stroke volume * Heart rate
Mean arterial pressure = Cardiac output * Total peripheral resistance
Stroke volume = End diastolic volume – End systolic volume
Stroke volume depends on:
- Preload: venous tone / Circulating blood volume
- Afterload: arterial tone
– Cardiac output (CO): quantity of blood pumped by the heart in 1 minute (normal= 3500 ml)
– Stroke volume (SV): quantity of blood pumped by the heart in 1 contraction (normal=50 ml)
– Heart rate (HR): Number of pumps (normal=50)
– Mean arterial pressure (MAP): average pressure
– Total peripheral resistance (TPR): circulatory system resistance to blood flow
-Exercise: ↑ contractility, then ↑ stroke volume, finally ↑ cardiac output
-Heart failure: ↓ cardiac output, ↓ stroke volume
-Myocardial infarction: ↓ contractility, then ↓ stroke volume, finally ↓ cardiac output
-Vagus nerve stimulation: ↓ heart rate, then ↓ contractility, and finally ↓ stroke volume and also cardiac output
-Vasodilators: ↓ contractility, then ↓ stroke volume, finally ↓ cardiac output