If the heart is the fun, amazing inside bit of one orange, the pericardium could be contrasted to the peel around it. Choose peel, it deserve to seem vaguely unexciting – the is until you discover some that its an extremely important (appeeling. Ahem.) physiological functions 1.

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In scientific terms, the pericardium is a fibro-serous, fluid-filled sack that surrounds the muscular body of the heart and also the roots of the great vessels (the aorta, pulmonary artery, pulmonary veins, and the superior and inferior vena cavae).

This post will offer an rundown of the functions, structure, innervation, and clinical definition of the pericardium.


Anatomical framework

The pericardium is comprised of two key layers: a hard external layer known as the fibrous pericardium, and a thin, inner layer recognized as the serous pericardium (to overextend the orange metaphor, the external peel might be thought of as the fibrous layer, with the inner white stuff gift the serous layer).

Fibrous Pericardium

Continuous with the main tendon the the diaphragm, the fibrous pericardium is make of hard connective tissue and is reasonably non-distensible. Its rigid structure stays clear of rapid overfilling the the heart, but can add to major clinical after-effects (see cardiac tamponade).

Serous Pericardium

Enclosed within the fibrous pericardium, the serous pericardium is itself split into two layers: the outer parietal layer that lines the interior surface the the fibrous pericardium and also the internal visceral layer that develops the external layer that the heart (also well-known as the epicardium). Each layer is comprised of a single sheet of epithelial cells, known as mesothelium.

Found in between the outer and inner serous layers is the pericardial cavity, which has a little amount the lubricating serous fluid. The serous fluid serves to minimize the friction produced by the heart as it contracts.


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Fig 1 – summary of the class of the heart wall.


The bespeak of these layers have the right to be remembered using the acronym Fart Police Smell Villains:

F – Fibrous great of the pericardiumP – Parietal great of the serous pericardiumS – Serous fluidV – Visceral layer of the serous pericardium

Functions

The pericardium has countless physiological roles, the most necessary of i beg your pardon are in-depth below:

Fixes the heart in the mediastinum and also limits that is motion. Continuous of the love is possible because the pericardium is attached come the diaphragm, the sternum, and the tunica adventitia (outer layer) that the great vesselsPrevents overfilling of the heart. The relatively inextensible fibrous great of the pericardium prevents the love from boosting in dimension too rapidly, for this reason placing a physical limit on the potential size of the organLubrication. A thin film that fluid between the two layers that the serous pericardium to reduce the friction created by the heart together it move within the thoracic cavityProtection from infection. The fibrous pericardium serves together a physical barrier between the muscular body of the love and surrounding organs vulnerable to infection, such together the lungs.
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Fig 2 – Anterior view of the pericardium. Note the attachments to the diaphragm, and also the root of the good vessels.


Clinical Relevance: Transverse Pericardial Sinus

Formed as a an outcome of the embryological urgently of the heart tube, the transverse pericardial sinus is a passage with the pericardial cavity.

It is located:

Posterior to the ascending aorta and pulmonary trunk.Anterior to the exceptional vena cava.Superior to the left atrium.

In this position, the transverse pericardial sinus separates the heart’s arterial outflow (aorta, pulmonary trunk) from its venous inflow (superior vena cava, pulmonary veins).

The transverse pericardial sinus have the right to be provided to identify and also subsequently ligate the arteries the the heart throughout coronary artery bypass grafting.


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Fig 3 – The Transverse pericardial sinus, separating the significant arteries and veins. Additionally note the close connection of the fibrous pericardium and also the diaphragm


Clinical Relevance

Cardiac Tamponade

The relatively inextensible fibrous pericardium can cause problems once there is an accumulation of fluid, well-known as pericardial effusion, in ~ the pericardial cavity.

The rigid pericardium can not expand, and thus the heart is topic to the resulting enhanced pressure. The chambers can come to be compressed, thus compromising cardiac output.

Pericarditis

Pericarditis, or inflammation that the pericardium, has myriad causes, including bacterial infection and also myocardial infarction. The main symptom is chest pain, and also the condition can reason acute cardiac tamponade as result of an buildup of liquid in the pericardial cavity.

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By James Heilman, MD (Own work) , via Wikimedia Commons
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Fig 4 – Radiographic appearance of pericardial effusion (note the enlarged love shape).