Essentials Of Medical Anatomy: Pericardium and Heart. скачать в хорошем качестве

Essentials Of Medical Anatomy: Pericardium and Heart.

Pericardium and Heart. The lecture file is written on my blog site on this site: https://www.blogger.com/blog/posts/32... INTRODUCTION: Pericardium, comprising fibrous and serous layers, encloses the heart pulsating from ‘womb to tomb’. Heart is a vital organ, pumping blood to the entire body. Its pulsations are governed by the brain through various nerves. Since heartbeat is felt or seen against the chest wall, it appears to be more active than the ‘quiet brain’ controlling it. That is why there are so many songs on the heart and few on the brain. Meditation, yoga and exercise help in regulating the heart beat through the brain. DISSECTION. Make a vertical cut through each side of the pericardium immediately anterior to the line of the phrenic nerve. Join the lower ends of these two incisions by a trans- verse cut approximately 1 cm above the diaphragm. Turn the flap of pericardium upwards and sideways to examine the pericardial cavity. See that the turned flap comprises fibrous and parietal layer of visceral pericardium. The pericardium enclosing the heart is its visceral layer (Fig. 18.1a). Pass a probe from the right side behind the ascending aorta and pulmonary trunk till it appears on the left just to the right of left atrium. This probe is in the transverse sinus of the pericardium. Lift the apex of the heart upwards. Put a finger behind the left atrium into a cul-de-sac, bounded to the right and below by inferior vena cava and above and to left by lower left pulmonary vein. This is the oblique sinus of pericardium. Define the borders, surfaces, grooves, apex and base of the heart. Features. The pericardium (Greek around heart) is a fibroserous sac which encloses the heart and the roots of the great vessels. It is situated in the middle mediastinum. It consists of the fibrous pericardium and the serous pericardium (Figs 18.1b and 18.2). Fibrous pericardium encloses the heart and fuses with the vessels which enter/leave the heart. Heart is situated within the fibrous and serous pericardial sacs. As heart develops, it invaginates itself into the serous sac, without causing any breach in its continuity. The last part to enter is the region of atria, from where the visceral pericardium is reflected as the parietal pericardium. Thus parietal layer of serous pericardium gets adherent to the inner surface of fibrous pericardium, while the visceral layer of serous pericardium gets adherent to the outer layer of heart and forms its epicardium. FIBROUS PERICARDIUM. Fibrous pericardium is a conical sac made up of fibrous tissue. The parietal layer of serous pericardium is attached to its deep surface. The following features of the fibrous pericardium are noteworthy. 1 The apex is blunt and lies at the level of the sternal angle. It is fused with the roots of the great vessels and with the pretracheal fascia. 2 The base is broad and inseparably blended with the central tendon of the diaphragm. 3 Anteriorly, it is connected to the upper and lower ends of body of the sternum by weak superior and inferior sternopericardial ligaments (Fig. 18.3). 4 Posteriorly, it is related to the principal bronchi, the oesophagus with the nerve plexus around it and the descending thoracic aorta. 5 On each side, it is related to the mediastinal pleura, the mediastinal surface of the lung, the phrenic nerve, and the pericardiacophrenic vessels. 1 It protects the heart against sudden overfilling and prevents over expansion of the heart. SEROUS PERICARDIUM. Serous pericardium is thin, double-layered serous membrane lined by mesothelium. The outer layer or parietal pericardium is fused with the fibrous peri cardium. The inner layer or the visceral pericardium, or epicardium is fused to the heart, except along the cardiac grooves, where it is separated from the h