心脏的外形与结构

Contents 1. Introduction 2. Location, relationship & shape of the heart 3. Internal structures of heart chambers 4. Septum of the heart •The vascular system is a closed network of vessels in the body. It is subdivided into the cardiovascular and the lymphatic systems. •The cardiovascular system consists of the blood, the heart, and the blood vessels which include the arteries, capillaries and veins. It transports numerous substances to and from cells for their survival and is sometimes called the circulatory system. •The lymphatic system is composed of lymphatics, lymphoid tissue and lymphoid organs. It transports a fluid (called lymph) that has escaped from blood vessels back to bloodstream at the junction of the jugular and subclavian veins at both sides of the neck. The lymphatic system is an immune and defensive system of the body. Cardiovascular System •Heart •Arteries •Capillaries •Veins Blood Circulation •The flow of blood through the network of the blood vessels in the body over and over again is called blood circulation. •The blood circulation can be divided into two parts: systemic circulation and pulmonary circulation. •The systemic (greater) circulation is circulation of blood through which blood flows from left ventricle into the aorta and its branches to all parts of the body, and returns to the right atrium via the superior and inferior vena cava. •The systemic circuit carries oxygenated blood throughout the body and picks up carbon dioxide from body tissues. In this process, blood changes from arterial blood to venous blood; its color changes from scarlet to dark red. Blood vessels in the systemic circuit also (1) pick up nutrients from the digestive tract and deliver them to cells throughout the body, and (2) receive nitrogenous wastes from body cells and transport them to the kidneys for elimination in the urine. •The pulmonary (lesser) circulation is blood circulation through which blood flows from the right ventricle into pulmonary trunk and its branches to the lungs, and returns to the left atrium via the pulmonary veins. •When blood flows through capillaries in the lungs, it discharges carbon dioxide and picks up oxygen from the lung alveoli. So the blood changes back from venous blood to arterial blood, its color changes from dark red to scarlet as well. The arteries and veins of the pulmonary circuit have thinner walls than do systemic vessels of comparable diameter, reflecting the fact that the maximum arterial pressure here is only one-sixth that in the systemic circuit. •In spite of the blood circulation can be divided into the systemic circulation and pulmonary circulation, the systemic circulation and pulmonary circulation are interdependent. •The heart connects systemic circulation and pulmonary circulation, and the heart not only provides dynamic to systemic circulation, but also to pulmonary circulation. Functions of Vascular System •Transport •Maintain of internal environment •Immune and Defensive •Endocrine Vascular Anastomosis and Significance Between artery and artery Between vein and vein Between artery and vein: For instance, existing on tips of fingers, apex of nose and auricle 1. Size •Roughly equal clenched fist of the same individual •male: 300g; female: 250g •The size of the heart varies from person to person 2. Location •in the thoracic cavity •occupies middle medastinum •Enclosed by pericardium •2/3 in left, 1/3 in right The angle between the cardiac axis and midsagittal plane is proximately 45 degree. Since the heart has rotated slightly to the left during embryonic development, therefore, the atria are posterior and superior to the ventricles, and the right atrium and ventricle are anterior to the left atrium and ventricle and to the right. So: The right atrium forms the right border of the heart. The right ventricle forms most potions of sternocostal surface and small portions of diaphragmatic surface. The left atrium forms the base of the heart and lies in the back of the heart. The left ventricle forms the left border, apex and most portions of the diaphragmatic surface of the heart. 3. Relationships Anterior--sternum, 2~6 cartilages Posterior--5~8 thoracic vertebrae Inferior--Diaphragm Superior--great blood vessels Lateral—pleural cavity, lungs Please note: The heart varies in location during different phases of respiration and in pneumothorax. 心和心包的前方大部分被左、右肺前缘及胸膜腔遮掩，仅在下部有一三角形 区域不被肺及胸膜腔遮掩，心及心包在此三角区与胸骨体下部及左侧第4、5肋 软骨相邻，此区成为心包裸区，为心内注射的入路。故心内注射时可选择胸骨 左缘第四肋间隙进针，而不会伤及肺和胸膜。心和心包前面的上部可有部分胸 腺残余。 Posteriorly, there are the thoracic aorta, esophagus, bronchi, thoracic duct, azygos vein, vagus nerves, posterior mediastinal lymph nodes between the heart and vertebral column. Since the left atrium forms most portions of the base (posterior surface of the heart), an enlarged left atrium may compress the esophagus. Laterally, the heat is closely related to the pleural cavities and the lungs, the phrenic nerve and pericardiacophrenic vessels descend between the pericardium and mediastinal pleura. Superiorly, great blood vessels leave and enter the heart. The pumonary trunk arises from the right ventricle. Its inferior part is enclosed by the pericardium. The ascending aorta arises from the left ventricle and is also enclosed by the pericardium. The space between the bifurcation of pulmonary trunk and aortic arch is the aortic window. The superior vena cava enters the right atrium, its inferior part is within the pericardial cavity. Inferiorly, the fibrous pericardium is fused with the diaphragm. The diaphragm separates the heart from the left lobe of live and stomach. The angle formed by the pericardium and diaphragm is known as the cardiodiaphragmatic angle. Lateral to this angle, between the pericardium and mediastinal pleura are some fats, which form fatty pad. 4. Shape The heart is anteroposterior a little flattened pyramidal in shape. Therefore, it is generally described as having an apex, a base, two surfaces, three borders and four groves. Apex •formed by left ventricle • point to the left, forward, downward 9 cm Base •Posterior part of the heart •Formed by left, right atria and one part of the left ventricle •face to the right, dorsalward, upward Base High posterior wall (straight posterior wall) Sternocostal Surface •anterior wall •formed by right atrium, ventricle and left ventricle Surfaces (2) Sternocostal Surface Diaphragmatic Surface •inferior wall •formed by left ventricles (most portion) and right ventricle (small portion) Diaphragm surface Right Border —---formed by right atrium, vertical Inferior Border —formed by left and right ventricles, sharp, horizontal Left Border —-----formed by left ventricle and atrium, rounded, oblique Borders (3) 左缘 右缘 下缘 左缘 下缘 右缘 1. Coronary groove ---------------------------separate atria and ventricle 2. Anterior interventricular groove ----separate left and right ventricles 3. Posterior interventricular groove ---separate left and right ventricles 4. Interatrial groove --------------------------separate left and right atria Grooves (4) 冠状沟 需要注意的是： •前、后室间沟在打开心包腔后并不明显， 因为沟内有血管、神经、淋巴管，并被 脂肪组织充填。 •此外，前房间沟也不明显，因为被主动 脉和肺动脉干掩盖。 •后房间沟明显，位于上、下腔静脉的左 侧，可作为房间隔手术的重要定位标志