Ventricle

The ventricle meaning can be defined as the lower chamber of the heart that is used to pump the blood to the rest of the body. Ventricles pump the blood out of the body into the circulatory system. In the human body, there are two heart ventricles which are termed as right and left ventricles, the important muscular differentiation of the ventricles from the atrium is the presence of the thick muscular wall compared to the atrium. This article focuses on the understanding of what are ventricles, the location and features of the right ventricle, location, and features of the left heart ventricle, interventricular septum, ventricle function, and pathology of the ventricle. This article also deals with a brief review of cardiac anatomy.

Cardiac Anatomy

The cardiac system of the human body consists of two atriums and two ventricles. The heart location can be described as the mediastinal located structure in the pericardial cavity.  The heart is obliquely positioned, according to the anatomical position, the heart is posterior to the sternum, superior to the diaphragm. The heart is surrounded by a heart wall, the heart wall has three layers they are as follows,

Pericardium- The outermost layer of the heart has a fibrous sac-like structure from the outside and the inner surface is parietal. 

Epicardium- This is the layer just below the pericardium. It is also known as the visceral layer of the pericardium, it is the layer that is surrounded by the blood vessels that allow the coronary circulation in the heart.  

Myocardium- It is the middle thickest layer of the heart. It is important to note that the heart ventricles have thicker layers of the myocardium than the heart atrium. One of the specializations of the myocardium is the presence of the intercalated disk; an intercalated disk can be defined as the border or plasma membrane of the two muscle fiber cells. These intercalated disks ensure the connection between the left and right ventricle and similarly left and right atrium. The coordinated contraction of the atrium and ventricle is gained through the action of this intercalated disk.  It is important to note that the valves of the heart lack this intercalated disk

Endocardium- The endocardium is the innermost layer of the heart wall. The coronary arteries and veins are present till this layer to ensure coronary circulation.

The important part of heart anatomy is the presence of valves. It is also important to understand the anatomical positioning and function of the valve to understand the ventricle function. There are four major valves present in the heart; they are two atrioventricular valves and two semilunar valves. Atrioventricular valves are present in between each heart atrium and heart ventricles. The valve between the left atrium and left ventricle is known as the bicuspid valve or mitral valve, whereas the valve present between the right atrium and right ventricle is known as the tricuspid valve. The semilunar valves are present between the heart ventricles and blood vessels carrying blood out of the heart, there are two semilunar valves namely, the pulmonary valve and aortic valve.

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Right Ventricle

It is important to understand what ventricles are to understand the function of the ventricle. The right ventricle is the lower chamber of the heart which is closer to the apex of the heart. The right heart ventricle collects blood from the right atrium through the tricuspid valve. The deoxygenated blood from the right ventricle is carried to the lungs by the pulmonary artery. According to the ventricle meaning the ventricle pumps blood out of the heart. It is interesting to note that the overall size of the right ventricle is smaller than the left ventricle. The right ventricle is one-third of the thickness of its atrium counterpart. It is convex in shape and lies between the 3rd and 6th costal cartilages. The interventricular septum acts as the left wall of the posterior of the right ventricle.  The right ventricle has the pulmonary semilunar valve. These valves guard the flow of blood out of the heart.

The tendon of the infundibulum also known as the conus ligament is one of the important structures of the right ventricle. It can be defined as the band of collagenous tissue. These tissues extend from the conus arteriosus to the aortic root. 

Another important internal feature of the right ventricle is the presence of the papillary muscles, the primary function of these muscles is to prevent leakage of the blood through AV valves during the systole (ventricular contraction).there are three types of papillary muscle they are as follows,

1. Anterior Papillary Muscle- It originates from the right ventricle’s anterior walls. They are connected to the tricuspid leaflet at the anterior and posterior sides. That is the largest muscle among all the papillary muscles.

2. Posterior Papillary Muscle- They are comparatively smaller than the anterior muscle. The origination can be defined anatomically from the inferior wall of the right ventricle. They are attached to the tricuspid valve via the septal and posterior sides of the valve.

3. Septal Papillary Valve- They are attached to the interventricular septum, they are also attached to the tricuspid valve. 

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Left Ventricle

According to ventricle meaning the left ventricle maintains the coronary circulation during the relatively high-pressure systemic circulation. The left ventricle is comparatively larger. The pulmonary veins carry oxygenated blood to the left atrium, the blood moves into the ventricle through the bicuspid valve ( also known as a mitral valve) to the left ventricle. The ventricle pushes the blood out from the heart by ventricular contraction (systole) through the aortic valve and into the aorta, which then divides into various capillaries.

The cardiac grooves are also an important feature of the left ventricle, these grooves provide the physical distinction between the right atrium and the left atrium. It is also important to note that the valves both semilunar and atrioventricular are closely associated with each other in comparison to the right heart ventricles. There is the presence of a fibrous subaortic curtain, this originated from the right and left arches of the posterior side of the aortic valve. The work of this fibrous subaortic curtain is to separate the aortic valve from the mitral valve. The left ventricle also contains the papillary muscle but they are comparatively larger in size. The papillary muscle prevents blood leakage during the ventricular systole.

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Ventricle Function

The primary role of the ventricle is to pump blood out of the heart either in pulmonary circulation or in systemic circulation. In medical terms, the contraction is termed as systole, when the ventricles contract they are termed as ventricular systole. The relaxation of the heart chamber is known as the diastole similarly when the ventricle is in a relaxed state they are termed as the ventricular diastole. 

The atrial chamber when undergoing the systole the ventricles are in diastole that is the passive flow of the blood into the ventricles. At the end of the atrial systole, there is enough atrium pressure to push the residual blood into the ventricle and depolarize. 

As the blood volume reaches a critical level in the ventricle, it generates enough pressure for the opening of semilunar valves and the closure of AV valves, as the systole of the ventricle ends blood moves out through blood vessels, and the ventricles depolarize.

Isovolumetric contraction is that phase during which the ventricles are in systole but the intraventricular contraction is not sufficient to open the semilunar valves thus there is no net blood loss from the ventricle. To exit the isovolumetric contraction phase the pressure required is approximately 8 mmHg on the right side, and 85 mmHg on the left ventricle.

Ventricular Pathology

The disorders associated with ventricles can be broadly classified as congenital and acquired disorders that affect the ventricles. The table listed below gives an overview of the disorder: