Anatomy of the heart and lungs.pptx

Anatomy of the heart and lungs Dr Melissa Jones Learning Objectives • Identify surface anatomy landmarks of the thorax • Identify the divisions of the mediastinum and the structures found within each division • Describe the anatomy of the heart • Understand the circulation of blood from the heart...

Anatomy of the heart and lungs Dr Melissa Jones Learning Objectives • Identify surface anatomy landmarks of the thorax • Identify the divisions of the mediastinum and the structures found within each division • Describe the anatomy of the heart • Understand the circulation of blood from the heart to the rest of the body • Describe the anatomy of the lungs • Understand the functional anatomy of the pleurae • Understand simple pathologies related to the heart and lungs Mediastinum Collection of structures that lie between the two pleural cavities Superior mediastinum – extends upwards, terminating at the superior thoracic aperture Superior T4 / T5 Inferior Sternal angle Anterior Middle Inferior mediastinum – extends downwards, terminating at the diaphragm Posterior Superior mediastinum Lies between the superior thoracic aperture and an imaginary line from the sternal angle (anteriorly) and vertebrae T4/T5 posteriorly Contents: Great vessels Trachea Oesophagus Thymus Vagus nerves Phrenic nerves Recurrent laryngeal nerves Thoracic duct Thymus Brachiocephalic veins Great arteries Vagus and Phrenic nerves • Trachea • • • • Superior mediastinum Brachiocephalic trunk Trachea Left common carotid artery Right brachiocephalic vein Why can’t we see the oesophagus? Left brachiocephal ic vein The Heart The heart forms part of the middle mediastinum The heart is surrounded by the pericardium Surface anatomy Upper Right: 3rd costal cartilage Lower Right: 6th Costal cartilage Upper Left: left 2nd costal cartilage Lower Left: 5th Intercostal Space Midclavicular line Heart in situ Aorta Superior vena cava Pulmonary trunk Right atrium Left ventricle Apex Right ventricle Heart in situ Aorta Superior vena cava (SVC) Pulmonar y trunk Orientation of heart RA RV LV Flow of blood through heart From body via SVC To lungs via pulmonary artery To lungs via pulmonary artery PT From RV to PT through PULMONARY VALVE (semilunar valve) RA From RA to RV through TRICUSPID VALVE RV From body via IVC Flow of blood through heart From LV to aorta through AORTIC VALVE (semilunar valve) From lungs via pulmonary veins Aort a From lungs via pulmonary veins LA From LA to LV through MITRAL VALVE (bicuspid valve) LV Pericardium • Fibrous pericardium • Protective layer • Attached to great vessels and diaphragm • Anchors heart in place • Serous pericardium • Parietal layer attached to fibrous layer • Visceral layer attached to surface of heart - epicardium Pericardium • Fixes heart in mediastinum and limits movement • Protection from infections coming from other organs • Prevents excessive dilation of heart in cases of acute volume overload • Lubrication • Pathology: • Pericardial effusion leading to cardiac tamponade Identify the chamber or vessel C A B D Internal features of right atrium Receives deoxygenated blood SVC Fossa ovalis TRICUSPID VALVE – between right atrium and right ventricle IVC Opening for coronary Foetal circulation •Foramen ovale shunts blood from RA to LA (bypassing pulmonary circulation) Internal features of right ventricle Pulmonary trunk TRICUSPID VALVE – between right atrium and right ventricle Tricuspid valve Chordae tendineae Papillary muscles Pulmonary valve (semilunar) Internal features of left atrium and ventricle Receives oxygenated blood Aortic valve (semilunar) to ascending aorta Thicker myocardium MITRAL VALVE – between left atrium and left ventricle (cut away in the diagram) Internal features of left ventricle Papillary muscles MITRAL VALVE – between left atrium and left ventricle Mitral valve Chordae tendineae Fibrous skeleton • Anchors the valves of the heart, and gives attachment to the myocardium. • It consists of four fibrous rings • each surrounding one of the valves • And a membranous part of the interventricular septum Atrioventricular Valves Diastole A-V valves open to allow blood to flow from the atria into the ventricles • Ventricular pressure is lower than atrial pressure • Occurs when ventricles are relaxed, chordae tendineae are slack and papillary muscles are relaxed Systole A-V valves close preventing backflow of blood into atria • Occurs when ventricles contract pushing valve cusps closed, chordae tendineae become taut and papillary muscles contract to prevent cusps from everting Semilunar valves • Prevent backflow from aorta and pulmonary trunk into ventricles • Passive action • Systole of ventricles opens valves • Diastole of ventricles decrease blood pressure • Backflow fills cusps and closes valves Pulmonary valve Aortic valve Heart valves Pulmona ry Aort ic Mitr al Tricus pid Identify… B A C The conduction system 1. Sinoatrial (SA) node – (pacemaker) generates 70 – 80 pulses per minute - Atria contract 2. The impulses pause (0.1 sec) at the atrioventricular (AV) node so that the ventricles have time to fill SA node 3. The atrioventricular bundle (Bundle of His) connects the atria and ventricles AV node 4. The AV bundle branches conduct the impulses through the interventricular septum 5. The Purkinje fibres stimulate the contractile cells of both ventricles - Starts at apex and moves superiorly Bundle of His AV bundle branches Purkinje fibres Pacemakers Innervation of the heart • Supplied by the cardiac plexus • Lies anterior to bifurcation of trachea and posterior to arch of aorta • Cardiac plexus contains: • Parasympathetic (from vagus nerve (CNX)) • Sympathetic (from sympathetic trunk) • General visceral afferents (GVA) Innervation of heart Vagus (Parasympathetic) Decreased rate of firing Sympathetic nerves Spinal levels T1-T5 Increased rate of firing General visceral afferents (GVA) Spinal levels T1-T5 Referred pain • Sympathetic fibres (from heart) enter spinal cord between T1 and T5 levels • At these spinal levels somatic afferents (sensory nerves from the skin) also enter the spinal cord • Here both sets of nerves travel in the same tract(carrying pain sensation) in the spinal cord to reach the brain • The brain is unable to distinguish between visceral and somatic sensation and so pain is experienced within the somatic region Coronary arteries Aorta PT Right coronary artery LA RA Left coronary artery Coronary arteries Aorta PT Right coronary artery LA RA Left coronary artery Coronary arteries Right coronary artery Posterior interventricular artery Right marginal artery Coronary arteries Left coronary artery Left circumflex artery Left marginal artery Left anterior descending (LAD) artery Coronary arteries Left coronary artery Right coronary artery Left circumflex artery Left marginal artery Posterior interventricular artery Right marginal artery Left anterior descending (LAD) artery Coronary arteries Right coronary artery Left coronary artery Cardiac veins Coronary sinus Great cardiac vein Small cardiac vein Anterior interventricular vein Middle cardiac vein Blood Supply to the Conduction System • The RCA usually supplies the SA node LCA • The RCA usually supplies the AV node • The interventricular (descending) arteries supply the bundle branches LAD AV nodal from RCA PDA R L Myocardial infarction 2. Right coronar y artery 3. Circumflex branch 1. Left anterior descending Heart valves Pulmona ry Aort ic Mitr al Tricus pid Upper Right: 3rd costal cartilage Lower Right: 6th Costal cartilage Upper Left: left 2nd costal cartilage Lower Left: 5th Intercostal Space Midclavicular line Aortic: right 2rd intercostal space Tricuspid: 6th intercostal space Pulmonary: left 2nd intercostal space Mitral: 5th Intercostal Space Midclavicular line Heart Valves S1 (Lub) M1 & T 1 Systole S2 (Dub) A1 & P 1 S1 M1 & T 1 Diastole Valves can become dysfunctional if they do not open properly (stenosis) or if they do not close properly (regurgitation). There are many causes of valvular dysfunction including aging, rheumatic fever and bacterial Break Muscles of chest wall Sternocleidomast oid CNXI Pectoralis minor Pectoralis major Pectoral nerves C5-T1 Pectoral nerves C5-T1 Serratus anterior Long thoracic nerve (C5 - 7) inspiration Radical mastectomy can damage long thoracic nerve (C5,6,7) = winging of the scapula Muscles of chest wall Sternocleidomast oid CNXI Pectoralis minor Pectoralis major Pectoral nerves C5-T1 Pectoral nerves C5-T1 Serratus anterior Long thoracic nerve C5,6,7 Rectus abdominis Intercostal and subcostal nerves T7 – T12 inspiration External intercostal muscles expiration Intercostal nerves T2 –T11 Muscles of chest wall The intercostal muscles lie in the intercostal spaces between the ribs and are organised into three layers Run inferoanteriorly from the rib above to the rib below External intercostal External intercostal Internal intercostal Inner most intercostal Internal and innermost intercostal Run from the rib above to the rib below, but in an opposite direction (inferoposteriorly) Chest wall neurovasculature The neurovascular bundle, consisting of the intercostal nerve and vessels, lies in between the internal and the innermost intercostals within the costal groove Vein azygous Artery Nerve Diaphragm Thin skeletal muscle that separates the thoracic cavity from the abdominal cavity. It is an important muscle for respiration Phrenic nerve (C3,4,5) Inferior vena cava – T8 Oesophagus – T10 Aorta – T12 Pleura The pleurae refer to the serous membranes that line the lungs and thoracic cavity. Visceral pleura Parietal pleura Covers the surface of the lungs Thoracic wall and diaphragm Phrenic nerve C3 -5 Parietal pleura Visceral pleura Sympathetic and parasympathetic Intercostal nerves T2 – T12 Not sensitive to pain Sensitive to pain Phrenic nerve C3 -5 Intercostal nerves T2 – T12 NORMAL CHEST X RAY PNEUMOTHORAX What am I looking at? Anteriorly and posteroinferiorly, the pleural cavity is not completely filled by the lungs. This gives rise to recesses. costophrenic recess These recesses are of clinical importance, as they provide a location where fluid can collect. Sharp costophrenic angle Blunted costophrenic angle = Fluid = pleural effusion Which x-ray shows a pleural effusion? Lungs MC L MAL Apex of lungs lie 2cm above clavicles Cardiac notch at 4th rib Lungs are found at ribs 6, 8 and 10 Pleura are found at ribs 8, 10 and 12 Anterior view Posterior view Pulmonary artery Lungs Bronchus Pulmonar y veins Horizont al fissure Oblique fissure Superior lobe Superior lobe Middle lobe Inferior lobe Right lung has 3 lobes la gu n i L Inferior lobe Left lung has 2 lobes Oblique fissure Bronchus Pulmonary artery Pulmonar y veins Bronchopulmonary segment The bronchopulmonary segments are the largest functional divisions of the anatomical lobes; each receiving their own air and blood supply Tracheobronchial tree Trachea • • • • The trachea marks the beginning of the tracheobronchial tree It arises at the lower border of cricoid cartilage in the neck, as a continuation of the larynx The trachea divides at the level of the sternal angle into main bronchi = carina Numerous divisions of the bronchi into the bronchioles and further into alveoli Main bronchus Lobar bronchus Segmental bronchi Conducting bronchioles Terminal bronchioles Respiratory bronchioles Alveolar ducts Alveolar sacs What am I looking at? Normal Chest X Ray Hyper expansion Destruction of alveolar walls Reduced surface area Loss of elastic tissue Narrowed bronchioles Emphysema COPD emphysema Emphysema Posterior Mediastinum Lies anterior to vertebrae L5 - T12, posterior to the pericardium, inferior to the sternal angle Contents: Azygous vein (+hemiazygous) Vagus Oesophagus Thoracic duct Thoracic aorta Thoracic duct Azygous vein Thoracic aorta Oesophagus Sympathetic trunk Sympathetic chain ganglia (T1 –L2) • Lie on each side of the vertebral column, extending from the base of the skull to the coccyx where the two chains fuse together Fight or flight response Stellate ganglion The stellate ganglion is formed by the fusion of the inferior cervical and superior thoracic sympathetic ganglia and provides most of the sympathetic innervation to the head, neck, upper extremity, and a portion of the upper thorax. The End