Where is pericardial cavity located

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Over one year, that would equal 10,, liters or 2. In order to understand how that happens, it is necessary to understand the anatomy and physiology of the heart. The human heart is located within the thoracic cavity, medially between the lungs in the space known as the mediastinum.

Figure 1 shows the position of the heart within the thoracic cavity. Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane known as the pericardium, or pericardial sac, and sits in its own space called the pericardial cavity. The dorsal surface of the heart lies near the bodies of the vertebrae, and its anterior surface sits deep to the sternum and costal cartilages.

The great veins, the superior and inferior venae cavae, and the great arteries, the aorta and pulmonary trunk, are attached to the superior surface of the heart, called the base. The base of the heart is located at the level of the third costal cartilage, as seen in Figure 1. The inferior tip of the heart, the apex, lies just to the left of the sternum between the junction of the fourth and fifth ribs near their articulation with the costal cartilages. The right side of the heart is deflected anteriorly, and the left side is deflected posteriorly.

It is important to remember the position and orientation of the heart when placing a stethoscope on the chest of a patient and listening for heart sounds, and also when looking at images taken from a midsagittal perspective.

The slight deviation of the apex to the left is reflected in a depression in the medial surface of the inferior lobe of the left lung, called the cardiac notch. Figure 1. The heart is located within the thoracic cavity, medially between the lungs in the mediastinum. It is about the size of a fist, is broad at the top, and tapers toward the base. The position of the heart in the torso between the vertebrae and sternum see the image above for the position of the heart within the thorax allows for individuals to apply an emergency technique known as cardiopulmonary resuscitation CPR if the heart of a patient should stop.

By applying pressure with the flat portion of one hand on the sternum in the area between the lines in the image below , it is possible to manually compress the blood within the heart enough to push some of the blood within it into the pulmonary and systemic circuits. This is particularly critical for the brain, as irreversible damage and death of neurons occur within minutes of loss of blood flow.

If you are unfamiliar with this song, you can likely find a version of it online. At this stage, the emphasis is on performing high-quality chest compressions, rather than providing artificial respiration. CPR is generally performed until the patient regains spontaneous contraction or is declared dead by an experienced healthcare professional.

When performed by untrained or overzealous individuals, CPR can result in broken ribs or a broken sternum, and can inflict additional severe damage on the patient. It is also possible, if the hands are placed too low on the sternum, to manually drive the xiphoid process into the liver, a consequence that may prove fatal for the patient.

Proper training is essential. This proven life-sustaining technique is so valuable that virtually all medical personnel as well as concerned members of the public should be certified and routinely recertified in its application. CPR courses are offered at a variety of locations, including colleges, hospitals, the American Red Cross, and some commercial companies.

They normally include practice of the compression technique on a mannequin. Figure 2. If the heart should stop, CPR can maintain the flow of blood until the heart resumes beating. By applying pressure to the sternum, the blood within the heart will be squeezed out of the heart and into the circulation.

Proper positioning of the hands on the sternum to perform CPR would be between the lines at T4 and T9. The shape of the heart is similar to a pinecone, rather broad at the superior surface and tapering to the apex.

A typical heart is approximately the size of your fist: 12 cm 5 in in length, 8 cm 3. Given the size difference between most members of the sexes, the weight of a female heart is approximately — grams 9 to 11 ounces , and the weight of a male heart is approximately — grams 11 to 12 ounces.

The heart of a well-trained athlete, especially one specializing in aerobic sports, can be considerably larger than this. Cardiac muscle responds to exercise in a manner similar to that of skeletal muscle. That is, exercise results in the addition of protein myofilaments that increase the size of the individual cells without increasing their numbers, a concept called hypertrophy.

Hearts of athletes can pump blood more effectively at lower rates than those of nonathletes. Enlarged hearts are not always a result of exercise; they can result from pathologies, such as hypertrophic cardiomyopathy. The cause of an abnormally enlarged heart muscle is unknown, but the condition is often undiagnosed and can cause sudden death in apparently otherwise healthy young people.

The human heart consists of four chambers: The left side and the right side each have one atrium and one ventricle. The ventricles serve as the primary pumping chambers of the heart, propelling blood to the lungs or to the rest of the body. There are two distinct but linked circuits in the human circulation called the pulmonary and systemic circuits.

Although both circuits transport blood and everything it carries, we can initially view the circuits from the point of view of gases. The pulmonary circuit transports blood to and from the lungs, where it picks up oxygen and delivers carbon dioxide for exhalation. The systemic circuit transports oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation.

The right ventricle pumps deoxygenated blood into the pulmonary trunk , which leads toward the lungs and bifurcates into the left and right pulmonary arteries. These vessels in turn branch many times before reaching the pulmonary capillaries , where gas exchange occurs: Carbon dioxide exits the blood and oxygen enters.

The pulmonary trunk arteries and their branches are the only arteries in the post-natal body that carry relatively deoxygenated blood. Highly oxygenated blood returning from the pulmonary capillaries in the lungs passes through a series of vessels that join together to form the pulmonary veins —the only post-natal veins in the body that carry highly oxygenated blood.

The pulmonary veins conduct blood into the left atrium, which pumps the blood into the left ventricle, which in turn pumps oxygenated blood into the aorta and on to the many branches of the systemic circuit. Eventually, these vessels will lead to the systemic capillaries, where exchange with the tissue fluid and cells of the body occurs. In this case, oxygen and nutrients exit the systemic capillaries to be used by the cells in their metabolic processes, and carbon dioxide and waste products will enter the blood.

The blood exiting the systemic capillaries is lower in oxygen concentration than when it entered. The capillaries will ultimately unite to form venules, joining to form ever-larger veins, eventually flowing into the two major systemic veins, the superior vena cava and the inferior vena cava , which return blood to the right atrium.

The blood in the superior and inferior venae cavae flows into the right atrium, which pumps blood into the right ventricle. This process of blood circulation continues as long as the individual remains alive. Understanding the flow of blood through the pulmonary and systemic circuits is critical to all health professions.

Figure 3. Blood flows from the right atrium to the right ventricle, where it is pumped into the pulmonary circuit. The blood in the pulmonary artery branches is low in oxygen but relatively high in carbon dioxide.

Gas exchange occurs in the pulmonary capillaries oxygen into the blood, carbon dioxide out , and blood high in oxygen and low in carbon dioxide is returned to the left atrium. From here, blood enters the left ventricle, which pumps it into the systemic circuit. Following exchange in the systemic capillaries oxygen and nutrients out of the capillaries and carbon dioxide and wastes in , blood returns to the right atrium and the cycle is repeated.

Our exploration of more in-depth heart structures begins by examining the membrane that surrounds the heart, the prominent surface features of the heart, and the layers that form the wall of the heart. Each of these components plays its own unique role in terms of function. Figure 4. The pericardial membrane that surrounds the heart consists of three layers and the pericardial cavity. The heart wall also consists of three layers. The pericardial membrane and the heart wall share the epicardium.

The membrane that directly surrounds the heart and defines the pericardial cavity is called the pericardium or pericardial sac. The fibrous pericardium is made of tough, dense connective tissue that protects the heart and maintains its position in the thorax. The more delicate serous pericardium consists of two layers: the parietal pericardium, which is fused to the fibrous pericardium, and an inner visceral pericardium, or epicardium , which is fused to the heart and is part of the heart wall.

The pericardial cavity, filled with lubricating serous fluid, lies between the epicardium and the pericardium. In most organs within the body, visceral serous membranes such as the epicardium are microscopic. However, in the case of the heart, it is not a microscopic layer but rather a macroscopic layer, consisting of a simple squamous epithelium called a mesothelium , reinforced with loose, irregular, or areolar connective tissue that attaches to the pericardium.

This mesothelium secretes the lubricating serous fluid that fills the pericardial cavity and reduces friction as the heart contracts. If excess fluid builds within the pericardial space, it can lead to a condition called cardiac tamponade, or pericardial tamponade.

With each contraction of the heart, more fluid—in most instances, blood—accumulates within the pericardial cavity. In order to fill with blood for the next contraction, the heart must relax.

However, the excess fluid in the pericardial cavity puts pressure on the heart and prevents full relaxation, so the chambers within the heart contain slightly less blood as they begin each heart cycle.

Over time, less and less blood is ejected from the heart. If the fluid builds up slowly, as in hypothyroidism, the pericardial cavity may be able to expand gradually to accommodate this extra volume. Some cases of fluid in excess of one liter within the pericardial cavity have been reported.

Rapid accumulation of as little as mL of fluid following trauma may trigger cardiac tamponade. Other common causes include myocardial rupture, pericarditis, cancer, or even cardiac surgery. Removal of this excess fluid requires insertion of drainage tubes into the pericardial cavity. Premature removal of these drainage tubes, for example, following cardiac surgery, or clot formation within these tubes are causes of this condition.

Untreated, cardiac tamponade can lead to death. Inside the pericardium, the surface features of the heart are visible, including the four chambers. Auricles are relatively thin-walled structures that can fill with blood and empty into the atria or upper chambers of the heart.

You may also hear them referred to as atrial appendages. Major coronary blood vessels are located in these sulci. The deep coronary sulcus is located between the atria and ventricles. Located between the left and right ventricles are two additional sulci that are not as deep as the coronary sulcus. The anterior interventricular sulcus is visible on the anterior surface of the heart, whereas the posterior interventricular sulcus is visible on the posterior surface of the heart. Figure 5 illustrates anterior and posterior views of the surface of the heart.

Figure 5. Inside the pericardium, the surface features of the heart are visible. The wall of the heart is composed of three layers of unequal thickness. From superficial to deep, these are the epicardium, the myocardium, and the endocardium. The outermost layer of the wall of the heart is also the innermost layer of the pericardium, the epicardium, or the visceral pericardium discussed earlier.

Figure 6. The middle and thickest layer is the myocardium , made largely of cardiac muscle cells. It is built upon a framework of collagenous fibers, plus the blood vessels that supply the myocardium and the nerve fibers that help regulate the heart. It is the contraction of the myocardium that pumps blood through the heart and into the major arteries. It is the disposition of these 'tubes' of pericardium and vessels through the cavity that forms the oblique and transverse sinuses.

Excessive fluid within the pericardial cavity is termed a pericardial effusion. It can lead to cardiac tamponade. Pericardiocentesis may be used to treat, and possibly diagnose the cause of, an effusion.

While a range of clinical features exists, effusions commonly present with chest pain or dyspnea. Pericarditis refers to inflammation of the pericardium, which often presents with chest pain and fever. Typically, the pain worsens with inspiration or coughing and is alleviated by leaning forward or sitting. On auscultation, a friction rub is often present. Acute pericarditis can be attributed to both infectious and non-infectious causes.

While often idiopathic, many cases are thought to be viral with echovirus and coxsackievirus being the most common. Noninfectious causes of pericarditis include neoplasms and damage caused by myocardial infarction. Electrocardiograms in patients with pericarditis typically show ST-segment elevation in all leads besides aVR and V1. Dressler syndrome is a form of pericarditis, believed to be an autoimmune reaction to certain myocardial antigens, that occurs at least 2 to 3 weeks after myocardial infarction.

Constrictive pericarditis refers to fibrosis and thickening of the pericardium. The majority of cases of constrictive pericarditis are considered idiopathic. This refers to a paradoxical increase in jugular venous distension during inspiration. Cardiac tamponade occurs when an increase in pressure, due to causes such as hemopericardium or pericarditis, compresses the heart and restricts adequate cardiac output. By decreasing compliance, normal venous return to the right atrium is hindered.

Pulsus paradoxus, an exaggerated decrease in systolic blood pressure during inspiration, is also often seen. Akhter SA, The heart and pericardium. Thoracic surgery clinics. Pediatric cardiology. Current cardiology reports. Anatomy, Thorax, Heart and Pericardial Cavity.

Free Review Questions. Introduction Located within the mediastinum between the third and sixth costal cartilages, the heart functions to supply tissues throughout the body with oxygenated blood. Blood Supply and Lymphatics Perfusion of the myocardium and epicardium is dependent on coronary arteries, which are normally embedded within epicardial fat.

Nerves Cardiac function is dependent on properly timed contractions of the atria and ventricles. Muscles Moving superficially, the heart wall can be divided into the endocardium, myocardium, and epicardium. Physiologic Variants Dextrocardia refers to the congenital condition where the apex of the heart is directed toward the right side of the chest.

Surgical Considerations Coronary artery bypass grafting CABG is a procedure to restore cardiac tissue perfusion after a coronary artery becomes occluded. Clinical Significance Pericardial effusion refers to abnormal levels of fluid within the pericardial space. Feedback: Send Us Your Comments.