pericardio

Pericardio, or the pericardium, is a fibroserous sac that encloses the heart and the roots of the great vessels. It lies in the middle mediastinum and serves to protect and stabilize the heart within the chest.

It consists of two main components: the fibrous pericardium, a tough outer layer, and the serous pericardium, which is divided into a parietal layer lining the fibrous sac and a visceral layer (epicardium) covering the heart. The space between the parietal and visceral layers is the pericardial cavity, containing a small amount of lubricating fluid that reduces friction during heartbeats.

Anatomical attachments help anchor the heart. The fibrous pericardium attaches to the central tendon of the diaphragm, the sternum, and the adventitia of the great vessels. The serous layers reflect around the roots of the great vessels to form pericardial reflections.

Functions of the pericardium include stabilizing the heart within the thorax, limiting excessive movement and distention, and providing a lubricated seal that minimizes friction between the heart and surrounding structures during rotation and contraction. It also helps protect against infection and spreads inflammatory processes away from the heart.

Blood supply and innervation come from several sources, with important contributions from the pericardiacophrenic arteries (branch of the internal thoracic artery) and smaller arteries. Innervation is mainly via the phrenic nerves (C3–C5), with sensory fibers contributing to referred pain.

Clinical relevance includes pericarditis (inflammation), pericardial effusion (fluid buildup), and cardiac tamponade (compression of the heart by fluid). Diagnosis is often by echocardiography, with CT or MRI as supplementary imaging. Treatments range from anti-inflammatory therapy to pericardiocentesis or pericardiectomy in constrictive disease.