Pericardium

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Pericardium

Posterior wall of the pericardial sac, showing the lines of reflection of the serous pericardium on the great vessels.

A transverse section of the thorax, showing the contents of the middle and the posterior mediastinum. The pleural and pericardial cavities are exaggerated since normally there is no space between parietal and visceral pleura and between pericardium and heart.
Gray's	subject #137 524
MeSH	Pericardium

The pericardium is a double-walled sac that contains the heart and the roots of the great vessels.

1 Layers
2 Innervation
3 Diseases
4 Additional images
5 External links

[edit] Layers

There are two layers to this sac: the fibrous pericardium and the serous pericardium. The serous pericardium, in turn, is divided into two layers; in between these two layers there is a potential space called the pericardial cavity.

The fibrous pericardium is the most superficial layer. It is a dense connective tissue, protecting the heart, anchoring it to the surrounding walls, and preventing it from overfilling with blood. It is continuous with the outer adventitial layer of the neighboring great blood vessels.

The serous pericardium is deep to the fibrous pericardium. It contains two layers, both of which function in lubricating the heart to prevent friction from occurring during heart activity.

The layer next to the fibrous pericardium is the parietal layer.
The layer next to the heart is the visceral layer, also known as the epicardium.

Together these two layers form a continuous uninterrupted membrane. Between these two layers exists a small cavity called the pericardial cavity, which contains a supply of serous fluid.The serous fluid that is found in this space is known as the pericardial fluid.

[edit] Innervation

The fibrous pericardium and the parietal layer of the serous pericardium are sensory innervated by the phrenic nerves (C3-C5). The epicardium receives autonomic innervation from the underlying heart.

[edit] Diseases

Pericarditis is inflammation of the pericardium. It can cause fluid to build up in the sac (pericardial effusion). Excessive amounts of fluid may lead to cardiac tamponade by physically blocking the heart from beating properly or compression of the great vessels of the heart.