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Portrait of Pericardium

Anatomy · Heart & blood vessels

Pericardium

Double-walled sac around the heart

Middle mediastinum · serous membrane

The double-walled sac that encloses the heart and the roots of the great vessels. It has a tough outer fibrous layer and an inner serous layer, itself in two parts: the parietal layer lining the fibrous sac and the visceral layer (epicardium) on the heart surface. Between them lies the pericardial cavity with a thin film of lubricating fluid, normally about 15–50 mL.

How to spot them

  • ▸Outer fibrous pericardium: strong, inelastic, fused to the central tendon of the diaphragm
  • ▸Inner serous pericardium: parietal layer lines the fibrous sac; visceral layer covers the heart as the epicardium
  • ▸Pericardial cavity between the two serous layers, holding a little fluid
  • ▸Two recesses behind the heart: the transverse and oblique sinuses

What to know

A sac of two layers, one tough and fibrous, one thin and slippery, enclosing the organ in the middle mediastinum

Pericardium — fibrous and serous layers.

Fused below with the central tendon of the diaphragm and attached in front to the sternum by ligaments

Pericardium — the sternopericardial ligaments.

Its inner lining continues over the organ's surface as the epicardium

Pericardium — visceral layer of serous pericardium.

Fluid accumulating inside it faster than it can stretch compresses the chambers, causing low blood pressure, muffled sounds and raised neck veins

Pericardium — cardiac tamponade (Beck's triad).

Drained by inserting a needle just below the xiphoid process aiming toward the left shoulder

Pericardium — pericardiocentesis.

Its supply from the phrenic nerve explains why inflammation here can refer pain to the shoulder

Pericardium — pericarditis, phrenic nerve (C3–C5).

A scratching sound heard on auscultation when its two inflamed layers rub together

Pericardium — pericardial friction rub.

Key ideas

  • The sac limits overfilling of the chambers and anchors the heart, while the serous fluid lets it beat with little friction.
  • Because the fibrous layer cannot stretch quickly, a small rapid accumulation of blood is far more dangerous than a large slow effusion.

Quick-fire facts

  • •Fibrous pericardium is fused with the central tendon of the diaphragm and merges with the adventitia of the great vessels.
  • •The pericardial cavity holds roughly 15–50 mL of serous fluid in health.
  • •The phrenic nerves run on its outer surface on each side, carrying sensory fibres from the fibrous and parietal layers.
  • •The transverse sinus lies behind the aorta and pulmonary trunk; the oblique sinus lies behind the left atrium.
  • •The epicardium is the visceral layer of the serous pericardium and carries the coronary vessels.
  • •Beck's triad of tamponade: hypotension, muffled heart sounds and raised jugular venous pressure.
  • •Congenital absence of the pericardium is rare and more common on the left.
  • •Uraemia, infection, myocardial infarction and cancer are common causes of pericardial inflammation or effusion.

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Sources