05 lung & pleura2012-01
Pleura and Lung By Prof. Saeed Abuel Makarem & Dr. Sanaa Al Sharawi Objectives By the end of the lecture, the student should be able to : • Describe the anatomy of the pleura: (subdivisions into parietal & visceral pleurae, nerve supply). • List the parts of parietal pleura and its recesses. • Describe the surface anatomy of both pleurae and lungs. • Describe the anatomy of lungs : (shape, surfaces, relations, nerve supply, blood supply and lymphatic drainage. • Describe the difference between right & left lungs. • Describe the formation of bronchopulmonary segments and its main characteristics. SUFACE ANATOMY OF PLEURA • • • • • • • • Apex: lies one inch above the medial 1/3 of the clavicle. Left pleura: The anterior margin extends from sternoclavicular joint to the level of 4th costal cartilage, then deviates for about 1 inch to left at 6th costal cartilage to form cardiac notch. Right pleura: The anterior margin extends vertically from sternoclavicular joint to 6th costal cartilage. Inferior margin : passes round chest wall, on the 8th rib in midclavicular line, 10th rib in mid-axillary line and finally reaching to the last thoracic spine. Posterior margin : along the vertebral column from the apex to the inferior margin. SURFACE ANATOMY OF LUNG • Apex, anterior border and posterior border • • • • • correspond nearly to the lines of pleura but are slightly away from the median plane. Inferior margin: as the pleura but more horizontal and finally reaching to the 10th thoracic spine. Oblique fissure: represented by a line extending from 3rd thoracic spine, obliquely ending at 6th costal cartilage. Transverse fissure only in right lung: represented by a line extending from 4th right costal cartilage to meet the oblique fissure. PLEURA • It is a closed serous sac which surrounds the lung and invaginated from its medial side by the root of lung. • It has 2 – layers: parietal pleura which lines the thoracic cavity. & visceral pleura which surrounds the lung, separated by a pleural cavity. • Pleural cavity: • Contains 5-10 ml. of serous fluid which lubricates both sufaces and allows the lungs to move free during respiration. Divisions of parietal pleura • 1- Cervical pleura: It is part of parietal pleura which protrudes up into the root of the neck. • 2-Costal pleura: It lines inner surface of ribs, costal cartilages, intercostal muscles and back of the sternum. • 3-Diaphragmatic pleura: It covers upper surface of the diaphragm. • 4-Mediastinal pleura: It covers mediastinal surface of the lung. Visceral Pleura firmly covers outer surfaces of the lung and extends into its fissures. The 2- layers (mediastinal parietal pleura & visceral pleura) are continuous with each other to form a tubular sheath (pleural cuff) that surrounding root of lung (vessels, nerves & bronchi) in the hilum of the lung. On the lower surface of root of the lung, pleural cuff hangs down as a fold called pulmonary ligament. Pleural Recesses Costodiaphragmatic recess : lies between costal & diaphragmatic parietal pleura along the inferior border. Costomediastinal recess : lies between costal & mediastinal parietal pleura along the anterior border. The lung reaches these recesses only in deep inspiration. Pleural Effusion • It is an abnormal accumulation of pleural fluid about 300 ml, in the Costodiaphragmatic recess • • • • • , (normally 5-10 ml of clear fluid) Causes: Inflammation, TB, malignancy, congestive heart disease. The lung is compressed & the bronchi are narrowed. Auscultation would reveal only faint & decreased breath sounds over the compressed or collapsed lung. Dullness on percussion over the effusion. Nerve Supply of Pleura • Parietal pleura…. • Costal P.P….by intercostal nerves. • Mediastinal P.P….by phrenic nerve. • Diaphragmatic P.P.: 1-Medially by phrenic nerve. 2-Peripheral part.. by lower 6 intercostal nerves. • Visceral pleura… sympathetic N.S. from pulmonary plexus. Blood supply of Pleura • Parietal pleura… by intercostal, internal thoracic & musculophrenic vessels. • Visceral pleura ….by bronchial vessles. Lymphatic Drainage: • Parietal pleura : into intercostal,, mediastinal & diaphragmatic Lymph Nodes. • Visceral pleura : into broncho-pulmonary Lymph Nodes in the hilum of the lung. LUNGS • Each lung has the following features: • It is conical in shape. • It has an apex, a base and 2 surfaces. • The costal surface of each lung borders the ribs (front and back). • On the medial (mediastinal) surface, the bronchi, blood vessels, and lymphatic vessels enter the lung at the hilum. LUNGS • Apex: projects into root of the neck (one inch above the medial 1/3 of the clavicle). It is covered by cervical pleura. It is grooved anteriorly by subclavian artery. • Base: (inferior= diaphragmatic surface) is concave and sits on the diaphragm. Borders: Anterior & Posterior • Anterior border : is sharp, thin and overlaps the heart. • Anterior border of left lung presents a cardiac notch at its lower end + thin projection called the lingula below the cardiac notch. • Posterior border : is rounded, thick and lies beside the vertebral column. Surfaces: Costal & Mediastinal Lateral & medial surfaces of right lung • Costal surface: • Convex. • Covered by costal pleura which separates lung from: ribs, costal cartilages & intercostal muscles. • Medial surface: • It is divided into 2 parts: • Anterior (mediastinal) part: • Contains a hilum in the middle (it is a depression in which bronchi, vessels, & nerves forming the root of lung). • Posterior (vertebral) part: • It is related to: bodies of thoracic vertebrae, intervertebral discs, posterior intercostal vessels & sympathetic trunk. RIGHT LUNG ROOT • 2 bronchi lie posterior. • Pulmonary artery is superior • 2 Pulmonary veins are inferior and anterior. LEFT LUNG ROOT • One bronchus lies posterior • Pulmonary artery is superior • 2 Pulmonary veins are inferior and anterior. Right lung • Larger & shorter than left lung. • Divided by 2 fissures (oblique & horizontal) into 3 lobes (upper, middle and lower lobes). Left Lung • Divided by one oblique fissure into -2 lobes, Upper and lower. • There is No horizontal fissure. • It has a cardiac notch at lower part of its anterior border. Mediastinal surface of right lung Cardiac impression • On the mediastinal surface of the right lung, you find these structures: • Azygos vein and its arch (posterior and over the root of the lung). • Vagus nerve posterior to the root. • Esophagus above and posterior to the root. • Phrenic nerve anterior to the root. • Cardiac impression: related to right atrium. • Below hilum and in front of pulmonary ligament: • Groove for I.V.C. Mediastinal surface of left lung Cardiac impression • On the mediastinal surface of the left lung, you will find these structures: • Descending aorta posterior to the root. • Vagus nerve posterior to the root. • Arch of the aorta over the root. • Groove for left common carotid artery. • Groove for left subclavian artery. • Phrenic nerve anterior to the root. • Cardiac impression : related to left ventricle. Blood supply of lung • Bronchial arteries (branches of descending thoracic aorta)….. supply oxygenated blood to bronchi , lung tissue & visceral pleura. • Bronchial veins : drain into azygos & hemiazygos veins. • Pulmonary artery which carries non-oxygenated blood from right ventricle to the lung alveoli. • 2 pulmonary veins : carry oxygenated blood from lung alveoli to the left atrium. Nerve Supply of the lung • Pulmonary plexus : • at the root of lung….is formed of autonomic N.S. from sympathetic & parasympathetic fibres. 1- Sympathetic F. from ..sympathetic trunk broncho-dilatation /and vasoconstriction. 2- Parasympathetic F. from….Vagus nerve …. Broncho-constriction and secretomotor to bronchial glands /and vasodilatation. Lymph drainage of the lungs • There are 2 lymphatic plexuses…. superficial & deep plexuses. • Superficial plexus (subpleural): lies under the visceral pleura and drain to bronchopulmonary nodes in the hilum of lung. • Deep plexus: • Lies along the bronchial tree & pulmonary blood vessels and drain into the pulmonary nodes within the lung substance. • Then into bronchopulmonary nodes in the hilum of lung. • Then into the tracheo-bronchial nodes at the bifurcation of trachea , and finally into broncho-mediastinal lymph trunks to end in thoracic duct (left) or in right lymphatic duct (right). Bronchi • The trachea divides into 2 main bronchi: • Right main bronchus: It divides before entering the hilum, it gives off superior lobar (secondary) bronchus. On entering hilum, it divides into middle & inferior lobar bronchi. • Left main bronchus: On entering hilum, it divides into superior & inferior lobar bronchi. Bronchial Divisions • Within the lung each bronchus divides into number of branches that can be divided into two groups: I- Conduction zone branches Primary (main) bronchi Secondary (lobar) bronchi Tertiary (segmental) bronchi (supply the bronchopulmonary segment) Smaller bronchi Bronchioles Terminal bronchioles II- Respiratory zone branches • Respiratory bronchioles • Alveolar ducts • Alveolar sacs • Alveoli Bronchopulmonary segments • They are the anatomic, functional, and surgical units of the lungs. • Each lobar (secondary) bronchus gives off segmental (tertiary) bronchi. • Each segmental bronchus divides repeatedly into bronchioles. • Bronchioles divide into terminal bronchioles, which show delicate outpouchings ‘the respiratory bronchioles’. Bronchopulmonary segments • The respiratory bronchioles end by branching into alveolar ducts, which lead into alveolar sacs. • The alveolar sacs consist of several alveoli, each alveolus is surrounded by a network of blood capillaries for gas exchange. Characteristics of Bronchopulmonary segments • It is a subdivision of a lung lobe. • It is pyramidal in shaped, its apex lies toward the root, while its base lies on the lung surface. • It is surrounded by connective tissue septa. • It has a segmental bronchus, a segmental artery, lymph vessels, and autonomic nerves. • The segmental vein lies in the inter- segmental C.T. septa between the segments. • A diseased segment can be removed surgically, because it is a structural unit.