If the heart is the fun, exciting inside little of one orange, the pericardium could be contrasted to the peel about it. Like peel, it deserve to seem vaguely unexciting – the is till you find out some that its very important (appeeling. Ahem.) physiological functions 1.

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

This write-up will offer an summary of the functions, structure, innervation, and clinical meaning of the pericardium.


Anatomical framework

The pericardium is consisted of of two key layers: a difficult external layer well-known as the fibrous pericardium, and a thin, internal layer recognized as the serous pericardium (to overextend the orange metaphor, the external peel might be thought of together the fibrous layer, with the inside white stuff being the serous layer).

Fibrous Pericardium

Continuous through the central tendon that the diaphragm, the fibrous pericardium is made of hard connective tissue and is reasonably non-distensible. Its strict structure avoids rapid overfilling that the heart, yet can contribute to major clinical aftermath (see cardiac tamponade).

Serous Pericardium

Enclosed within the fibrous pericardium, the serous pericardium is itself divided into two layers: the outer parietal layer that lines the internal surface that the fibrous pericardium and the internal visceral layer that forms the outer layer that the heart (also recognized as the epicardium). Each layer is consisted of 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 small amount that lubricating serous fluid. The serous fluid serves to minimization the friction generated by the heart as it contracts.


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Fig 1 – overview of the layers of the love wall.


The bespeak of this layers deserve to be remembered making use of the acronym Fart Police Smell Villains:

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

Functions

The pericardium has many physiological roles, the most vital of i beg your pardon are comprehensive below:

Fixes the heart in the mediastinum and limits its motion. Permanent of the love is possible because the pericardium is attached come the diaphragm, the sternum, and the tunica adventitia (outer layer) the the an excellent vesselsPrevents overfilling of the heart. The relatively inextensible fibrous layer of the pericardium stays clear of the heart from raising in dimension too rapidly, hence placing a physical border on the potential size of the organLubrication. A thin film that fluid in between the 2 layers the the serous pericardium to reduce the friction created by the heart as it moves within the thoracic cavityProtection indigenous infection. The fibrous pericardium serves as a physical barrier between the muscular body of the heart and nearby organs susceptible to infection, such as the lungs.
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Fig 2 – Anterior view of the pericardium. Note the attachments come the diaphragm, and also the roots of the great vessels.


Clinical Relevance: Transverse Pericardial Sinus

Formed as a an outcome of the embryological folding of the love tube, the transverse pericardial sinus is a passage v the pericardial cavity.

It is located:

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

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

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


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


Clinical Relevance

Cardiac Tamponade

The relatively inextensible fibrous pericardium can cause problems once there is an buildup of fluid, known as pericardial effusion, within the pericardial cavity.

The rigid pericardium cannot expand, and thus the love is topic to the resulting enhanced pressure. The chambers can end up being compressed, hence compromising cardiac output.

Pericarditis

Pericarditis, or inflammation the the pericardium, has myriad causes, including bacterial infection and also myocardial infarction. The main symptom is chest pain, and the condition can cause acute cardiac tamponade due to an accumulation 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 heart shape).