Pericardium and External Features of the Heart Lecture Notes (PDF)

Pericardium and External features of the Heart Dr. Rashid Aldahhan & Dr. Faiza Siddiqui Department of Anatomy Colleg...

Pericardium and External features of the Heart Dr. Rashid Aldahhan & Dr. Faiza Siddiqui Department of Anatomy College of Medicine, IAU Sunday, August 18, 2024  Learning objectives After participating in this lecture, students should be able to describe: ▪ The divisions of the mediastinum ▪ The boundaries and contents of anterior and middle mediastina ▪ The structure and function of the pericardium ▪ The external features of the heart. Sunday, August 18, 2024 PresentationHeart title and Pericardium  Study guide th Gray's anatomy for students, 4 ed. Pericardium Contents can be found in Chapter 3 & Heart Mediastinum & Pericardium: pp.184 -189 Heart: pp. 190 -194 Sunday, August 18, 2024 Presentation title  Interesting facts (FYI) ▪ In the normal human, heart beats approximately 100,000 times per day. ▪ About 2,000 gallons (7,572 liters) of blood travel daily ▪ Through about 60,000 miles (96,560 kilometers) of blood vessels. ▪ An average adult has 4.7 - 5.6 liters of blood. Sunday, August 18, 2024 Presentation title  Components CVS consists of: 1. The heart, which is a muscular pump 2. A closed system of blood vessels include: ▪ Arteries ▪ Veins ▪ Capillaries McMinn’s & Abraham’s Atlas 7th ed. Sunday, August 18, 2024 Presentation title  Thoracic cavity http://biology-forums.com/index.php?action=gallery;sa=view;id=8517 Sunday, August 18, 2024 Presentation title  What do you know about the mediastinum? Sunday, August 18, 2024 Presentation title  Mediastinum ▪ The area between the two pleural cavities, bounded anteriorly by the sternum and posteriorly by the thoracic part of the vertebral column ▪ It is divided into two portions by an imaginary line between the sternal angle and intervertebral disc between T4 / T5 1- Superior mediastinum –is bounded: ❖ Anteriorly by the manubrium sterni ❖ Posteriorly by the first four thoracic vertebrae ❖ Inferiorly by the sternal angle ❖ Superiorly by the superior thoracic aperture Gray’s Anatomy for students 4th ed. Sunday, August 18, 2024 Presentation title  Superior mediastinum Contents: 1. Thymus 2. Large veins 3. Large arteries 4. Trachea 5. Esophagus 6. Thoracic duct 7. Sympathetic trunks Sunday, August 18, 2024 Presentation title  Inferior mediastinum 2- Inferior mediastinum extends from below the sternal angle, to the diaphragm → It is further partitioned by the pericardial sac into the: 1. Anterior mediastinum 2. Middle mediastinum 3. Posterior mediastinum Sunday, August 18, 2024 Presentation title  Inferior mediastinum 1. Anterior mediastinum: is posterior to the body of the 1 sternum and anterior to the pericardial sac i. Inferior extension of the thymus gland ii. Fat iii. Connective tissue iv. Lymph nodes v. Mediastinal branches of the internal thoracic vessels vi. Sternopericardial ligaments 2. Middle mediastinum: contains the pericardium, heart, origins of the great vessels, various nerves, and smaller vessels. 3. Posterior mediastinum: between pericardium and lower thoracic vertebrae (T5-T12) Sunday, August 18, 2024 Presentation title  Mediastinum Gray’s Anatomy for students 4th ed. Sunday, August 18, 2024 Presentation title  Mediastinum superior inferior anterior middle posterior Between Between Heart & sternum & vertebrae & pericardium pericardium pericardium Thursday, September Sunday, August 1, 2022 18, 2024 Presentation title 7  What do you know about the Pericardium? Sunday, August 18, 2024 Presentation title  Pericardium ▪ Fibroserous sac ▪ Covers the heart and the root of the great vessels ▪ Consists of two components: 1. Fibrous pericardium: a tough CT outer layer that defines the boundaries of the middle mediastinum 2. Serous pericardium: thin and consists of two layers: A. The parietal layer B. The visceral layer Sunday, August 18, 2024 Presentation title Gray’s Anatomy for students 4th ed.  Fibrous pericardium ❖ A cone-shaped bag with its base on the diaphragm and its apex continuous with the of outer coats of the great vessels. ❖ Superiorly: it fuses with the tunica adventitia (perivascular connective tissue) of the great blood vessels passing through it, the aorta, the pulmonary trunk, the superior vena cava (SVC), and the pulmonary veins ❖ Inferiorly: the base is attached to the central tendon of the diaphragm by the pericardiacophrenic ligament and to a small muscular area of the diaphragm on the left side. It also fuses with the tunica adventitia of the inferior venae cavae ❖ Anteriorly: it is attached to the posterior surface of the sternum by sternopericardial ligaments. ❖ These attachments help to maintain the heart in its position in the thoracic cavity. ❖ The sac limits cardiac distention. Sunday, August 18, 2024 Presentation title  Serous pericardium  Closed sac lies within fibrous pericardium  Parietal layer lines the inner surface of the fibrous pericardium  Visceral layer (epicardium) adheres to the heart and forms its outer covering  The slit-like space between the parietal and visceral layers is referred to as the pericardial cavity.  Normally, the cavity contains a small amount of tissue fluid (~ 50 mL) → the pericardial fluid.  The pericardial fluid acts as a lubricant to facilitate (frictionless) movements of the heart. Snell’s Clinical Anatomy by regions 10th ed. Sunday, August 18, 2024 Presentation title  Pericardial sinuses Spaces posterior to the heart formed by the reflections of the serous pericardium around the great vessels The reflection around the large veins forms an inverted U/J-shaped cul-de-sac/recess ,posterior to the left atrium→the oblique sinus This runs along the long axis of the heart, from the apex to the ascending aorta. The relatively short horizontal space between the reflection of the serous pericardium around the aorta and pulmonary trunk and the reflection around the large veins → the transverse sinus Gray’s Anatomy for students 4th ed. Sunday, August 18, 2024 Presentation title  Pericardial sinuses Gray’s Anatomy for students 4th ed. Sunday, August 18, 2024 Presentation title  Arterial supply Venous drainage ▪ Internal thoracic artery branches: Pericardiophrenic artery Musculophrenic artery ▪ Branches of thoracic aorta:  Pericardiophrenic veins Bronchial  Veins of azygous system Esophageal Superior phrenic arteries ▪ Coronary arteries (visceral layer of serous pericardium) Sunday, August 18, 2024 Presentation title  Innervation ▪ Fibrous and parietal serous pericardium:  Phrenic nerves (C3, C4, and C5) “Pain” related to a pericardial problem may be referred to ? ▪ Visceral serous pericardium: Why?  Vagus nerve  Sympathetic trunk Sunday, August 18, 2024 Presentation title  Clinical anatomy →Pericarditis An inflammation of pericardium Clinical presentations: – Continuous central chest pain – Friction between opposing layers of serous pericardium (pericardial friction rub) – Possible pericardial effusion → excessive fluid in the pericardial cavity. – Pericardial effusion can compress the thin-walled atria and interfere with the filling of the heart during diastole and reduces cardiac output. – Such compression of the heart is called cardiac tamponade compression of the heart by an accumulation of fluid in the pericardial sac. Sunday, August 18, 2024 Presentation title  Pericardiocentesis ▪ Aspiration of fluid from the pericardial cavity ▪ To relieve cardiac tamponade ▪ Performed with a needle at the left infrasternal angle through the cardiac notch of the left lung. Sunday, August 18, 2024 Presentation title  Miss Jones is an otherwise healthy 31-year-old woman who presented to ER with a 4- day history of severe retrosternal chest pain. The pain was sharp and pleuritic in nature, worse on lying down and improved with sitting forward. There was radiation to the neck and shoulders. The chest pain was constant and not related to exertion. On physical examination, a pericardial friction rub was heard at end-expiration with the patient leaning forward. An ECG was done, and other investigations were carried out. ▪ What is the working diagnosis from the history given and which features of the presenting complaint and examination point towards this diagnosis? Sunday, August 18, 2024 Presentation title  The Heart ▪ A muscular organ that pumps blood around the body by circulating it through the circulatory system. ▪ Consists of four chambers  Two atria (inflow chambers)  Two ventricles (outflow) Sunday, August 18, 2024 Presentation title  Wall of the heart Made of three layers: 1. External layer → epicardium 2. Middle muscular layer → myocardium 3. Inner layer →endocardium Sunday, August 18, 2024 Presentation title  Surfaces and margins Margins: Apex 1. Obtuse Base 2. Inferior Surfaces: 3. Right 1. Anterior (Sternocostal) 4. Left 2. Inferior (diaphragmatic) 3. Right pulmonary 4. Left pulmonary Gray’s Anatomy for students 4th ed. Sunday, August 18, 2024  Borders Important to recognize for radiological evaluation of the heart Superior (atria, auricles) Inferior (right and left ventricles) Left (left auricle, left ventricle) Right (right atrium) Sunday, August 18, 2024 Gray’s Anatomy for students 4th  Base ▪ Quadrilateral and directed posteriorly ▪ It consists of: 1. The left atrium (primarily) 2. A small portion of the right atrium 3. The proximal parts of the great veins (SVC, IVC and the pulmonary veins) Apex  Formed by the inferolateral part* of the left ventricle  Positioned deep to the left fifth intercostal space ~ 9 cm from the midsternal line Sunday, August 18, 2024 Gray’s Anatomy for students 4th  Surfaces The anterior (sternocostal) surface consists of: ⌘ Mainly the right ventricle ⌘ Some of the right atrium on the right and ⌘ Some of the left ventricle on the left The heart in the anatomical position rests on the inferior (diaphragmatic) surface o It is formed by: ▪ The left ventricle ▪ A small portion of the right ventricle This surface faces inferiorly, rests on the diaphragm, and extends from the base to the apex of the heart. Sunday, August 18, 2024 Presentation title Gray’s Anatomy for students 4th  Surfaces The left pulmonary surface faces the left lung, is broad and convex, and consists of the left ventricle and a portion of the left atrium The right pulmonary surface faces the right lung, is broad and convex, and consists of the right atrium Sunday, August 18, 2024 Presentation title  External features ▪ Atrioventricular groove (coronary sulcus) The coronary sulcus circles the heart, separating the atria from the ventricles. It contains the right coronary artery, the small cardiac vein, the coronary sinus, and the circumflex branch of the left coronary artery. Interatrial groove ▪ Interatrial groove ▪ Interventricular groove The anterior and posterior interventricular sulci separate the two ventricles ▪ Auricles – extensions of each atria Sunday, August 18, 2024  External features Interventricular groove The anterior interventricular sulcus is on the anterior surface of the heart and contains the anterior interventricular artery and the great cardiac vein Interatrial groove The posterior interventricular sulcus is on the diaphragmatic surface of the heart and contains the posterior interventricular artery and the middle cardiac vein. Sunday, August 18, 2024 Sunday, August 18, 2024 Presentation title