What Is the Pericardium?

The pericardium is a membranous sac covering the surface of the heart. The pericardium is divided into a fibrous layer and a serous membrane layer. The fibrous layer is relatively tough and closely adheres to the wall layer of the serous membrane layer. The serosa layer is very thin, showing smooth and moist, and is divided into the wall layer and the dirty layer. The wall layer is closely attached to the inner surface of the fibrous layer, and the dirty layer is attached to the surface of the heart (that is, the epicardium). There is a cavity between the dirty and wall layers, which is called the pericardial cavity. The pericardium has a protective effect on the heart and can prevent excessive expansion of the heart cavity to maintain a constant blood volume.

The pericardium is a membranous sac covering the surface of the heart. The pericardium is divided into a fibrous layer and a serous membrane layer. The fibrous layer is relatively tough and closely adheres to the wall layer of the serous membrane layer. The serosa layer is very thin, showing smooth and moist, and is divided into the wall layer and the dirty layer. The wall layer is closely attached to the inner surface of the fibrous layer, and the dirty layer is attached to the surface of the heart (that is, the epicardium). There is a cavity between the dirty and wall layers, which is called the pericardial cavity. The pericardium has a protective effect on the heart and can prevent excessive expansion of the heart cavity to maintain a constant blood volume.

Chinese name

Pericardium

Pinyin

Xin Bao

Pericardial anatomy:

1. Pericardial:

The pericardium is the pericardium. It is an approximately cone-shaped fibrous serosa sac, which is wrapped around the heart and the roots of the large blood vessels entering and leaving the heart. Can be divided into fibrous pericardium and serous pericardium.

The fibrous pericardium is a tough, dense connective tissue sac. The upper part of the pericardium moves in and out of the heart with the adventitia of the large blood vessels. The bottom part of the fibrous pericardium is on the central tendon of the diaphragm.

The serous pericardium is composed of mesothelium and fibrous connective tissue, and is divided into two layers: dirty and wall. The wall layer is closely attached to the inner surface of the fibrous pericardium, and together constitutes the wall layer of the pericardium; the visceral layer is closely connected to the outside of the myocardium, and the two layers of the heart, the extracardiac, the viscera, and the wall, return to the root of the large blood vessels that enter and leave the heart and migrate to each other Therefore, a closed cavity is formed between the two layers, which is called the pericardial cavity. The cavity contains a small amount of liquid (serous fluid), called pericardial fluid, which is a filtrate of serum and contains a small amount of protein.

The pericardial cavity is enlarged in some places and is called the pericardial sinus.

The pericardium has the effect of maintaining the position of the heart and preventing excessive enlargement of the heart cavity. The pericardial fluid acts as a lubricant and reduces friction during heart movement. Due to the small elasticity of the fibrous pericardium, if there is a large amount of fluid in the pericardial cavity, it will not be easy to expand outward, which will compress the heart and limit its relaxation, affecting the return of venous blood.

2. Heart:

The heart is mainly composed of the heart muscle and is the center of the circulatory system. Its contraction and relaxation are the driving force for promoting blood circulation. Its anatomical and physiological characteristics are: Heart wall: divided into 3 layers, the inner layer is endocardium, which is composed of endothelial cells and connective tissue; the middle layer is the myocardium, the thickest; the outer layer It is the epicardium, that is, the visceral layer (inner layer) of the pericardium. There is a pericardial cavity between the pericardial wall (outer layer) and a small amount of serum. Myocardium and cardiac cavity: The heart is divided into four cavities, left and right atrium and ventricle, by the myocardium. The myocardium, which forms the atrium, is thin with two layers of muscle fibers. The superficial layer surrounds the left and right atria along the transverse diameter of the atrium and penetrates into the atrial septum; the deep layer surrounds the left and right atria respectively. The myocardium forming the ventricle is thicker, the left ventricle is thicker, and there are two layers of deep and shallow fibers, staggered to suit the heart's bleeding. When all muscle fibers contract at the same time, the inner diameter of the heart shrinks, pressure increases, and blood is injected into the blood vessels. When the heart is contracted, the papillary muscles are shortened, the chordae are tightened, and the atrioventricular valve is not flushed because of the increased pressure in the ventricular cavity, ensuring that blood flows forward in one direction. The myocardium and aorta and pulmonary arteries that make up the atrium and ventricle are attached to the central fiber scaffold of the heart. This stent consists of four thick connective tissue rings (located around the left and right atrioventricular and aortic and pulmonary arterial orifices), two The fiber triangle (located on the left and right sides between the left atrioventricular opening and the aortic opening) is connected with the funnel tendon. Pacing and conduction system: It consists of special myocardial cells, including the nodal node, the interstitial bundle, the interstitial bundle, the atrioventricular node, the atrioventricular bundle, the left and right bundle branches and their branches, and the Purkinje fiber network, which are the heart's impulse. The structure that quickly transmits the impulse to the common myocardium excites and contracts. This system can send impulses on time and is the material basis of the heart's autonomy. The sinoatrial node has the strongest autonomy and contains the most pacing cells. Blood supply to the heart: The left and right coronary arteries are the blood vessels that supply the heart with nutrition. They originate from the left and right aortic sinuses at the root of the aorta. The large branches are distributed on the surface of the myocardium, and the small branches enter the myocardium and are collected by the capillary network. The heart veins eventually form a coronary sinus and enter the right atrium.

The function of pericardium and its surrounding structure:

The pericardium is a fibrous serosa sac-like structure that surrounds the heart and the roots of large blood vessels. The outer layer is a tough and dense fibrous pericardium, and the inner serosal pericardium is divided into a wall layer and a visceral layer. The wall layer is lined on the inner surface of the fibrous pericardium, and the visceral layer is adhered to the surface of the heart, that is, the epicardium. The roots of the large blood vessels entering and leaving the heart are the reciprocal lines of the visceral and parietal layers. Between the visceral layer and the parietal layer is a narrow gap closed pericardial cavity. Contains a small amount of slurry to play a smooth role. There are many large blood vessels entering and exiting the pericardium at the bottom of the heart. The serous membrane wall and the visceral layer are folded back to form the pericardial oblique sinus and the pericardial sinus. Both sinuses are part of the pericardial cavity and have certain practical significance in cardiac surgery. The anterolateral, lateral and posterolateral of the pericardium are connected to the pleura, and the phrenic nerves and pericardial iliac vessels are located between the fibrous pericardium and the mediastinal pleura. At the thymic heart notch, the pericardium is in direct contact with the sternum and the left sternum. This area is called the bare pericardium. Here, you can make a connection between the left nipple and the lower end of the midline of the sternum, use the midpoint of the connection as the center, and make a 5cm diameter circle. This circle roughly indicates the range of the naked area. In addition to the pericardial fixation device above the patellar central tendon, there are still sternal pericardial ligaments and large blood vessels entering and leaving the heart. Because the pericardium is not fully fused with the central iliac tendon, they can still be separated in most areas, which is conducive to stripping the front of the diaphragm. In the anterior midline thoracoabdominal incision, it is not necessary to cut the heart cavity and cut the diaphragm. The pericardium has a protective effect on the heart, can prevent surrounding infections from spreading to the heart, restricts the expansion of the heart, and prevents the heart from rupturing quickly when the intracardiac pressure rises. When chronic inflammation of the pericardium results in the formation of connective tissue hyperplasia and scarring, constrictive pericarditis can have serious effects on cardiac function. The pericardial variation is mainly pericardial defect, with the left part defect being the most common. If the defect is large and accompanied by a corresponding pleural defect, the pericardial cavity and the pleural cavity can be communicated. There are also pericardial cysts and pericardial diverticulum.

Pericardial and pericardial-related diseases:

Pericardial effusion:

Overview:

Pericardial effusion can occur in most acute pericarditis. The pericardial effusion does not produce any symptoms, so it is easy to miss clinical diagnosis. The hemodynamic changes caused by pericardial effusion to increase the pressure in the pericardial cavity are related to the following factors: the amount of fluid in the pericardial effusion; the rate of fluid accumulation; the characteristics of the pericardial membrane. The nature of the fluid in the pericardial cavity varies according to the cause, and can be serous, serous-fibrinous, serous-blood, bloody, suppurative, cholesterolic, and chyle. The clinical manifestations are mainly dull chest pain. If the pericardial effusion is slow and the pressure in the pericardial cavity does not increase, the patient may have no symptoms. At the time of physical examination, if the volume of effusion is small but does not cause the pressure in the pericardial cavity to rise, there may be no positive signs. If the volume of pericardial effusion is large, the physical examination can find that the heart boundary expands to both sides, the heart sounds weaken, and the left lung The posterior lower part has a dullness zone below the lower angle of the scapula, which is called Ewart's sign, which is caused by the lungs being squeezed. If the amount of fluid in the pericardial cavity is large on X-ray examination, the shadow of the heart boundary is enlarged, the arcs of the left boundary of the heart disappear, and the pulsation of the heart is faint. Echocardiography is the most reliable method for diagnosing pericardial effusion. Generally, it can be found when the effusion volume exceeds 50ml. The treatment of this disease is mainly for the treatment of the primary disease, and the pericardial puncture discharge can relieve the symptoms caused by the compression of the surrounding organs.