FOCA 2023 Thorax I Lecture Notes PDF

FOCA 2023 Thorax I Thoracic Wall, Pleurae & Lungs Dr. Mark Hankin Professor & Senior Anatomist Director, Anatomical Sciences Education Center [email protected] Disclosures & Conflicts of Interest Authorship Anatomy & Physiology Revealed v4.0 2019, McGraw-Hill Clinical Anatomy: A Case Study Approach 20...

FOCA 2023 Thorax I Thoracic Wall, Pleurae & Lungs Dr. Mark Hankin Professor & Senior Anatomist Director, Anatomical Sciences Education Center [email protected] Disclosures & Conflicts of Interest Authorship Anatomy & Physiology Revealed v4.0 2019, McGraw-Hill Clinical Anatomy: A Case Study Approach 2013, McGraw-Hill Test Prep for the USMLE® – Clinical Anatomy Q&A 2019, Thieme Medical Publishers If you have used any of these resources, I hope you found them helpful. 2 Session Objectives 1. Describe the thoracic cavity, including its walls and compartments. 2. Describe the thoracic wall musculature and diaphragm, including their neurovasculature. 3. Describe the plural cavity and the relationship of the plurae to the lungs and thoracic walls. 4. Describe the anatomy of the tracheobronchial tree and lungs. 5. Describe the lymphatic drainage of the lungs. 6. Describe the innervation of the tracheobronchial tree. 3 Thoracic Cavity & Walls 4 Thoracic Cavity Walls, Roof & Floor Walls: Ribs, vertebrae & sternum Roof: Membranous – cervical pleura, referred to as the cupola (L. upsidedown cup) Floor: Diaphragm Functions Protection Support Breathing Cupola on tower of Montefiascone Cathedral, Italy 5 Thoracic Skeleton pairs 12 Ribs & costal cartilages 12 Vertebrae & IV discs Sternum - Manubrium, body & xiphoid process - Jugular (sternal) notch at superior border of manubrium angle (of Louis); O- Sternal location of articulation with rib 2 costal cartilage T1 2 OO T T12 Two apertures Gilroy, Atlas of Anatomy 3e 7.1A - Superior & inferior Anatomical: thoracic inlet Clinical: thoracic outlet 6 Joints Between Ribs & Vertebrae Transverse process posterior Tubercle Tuberclew facets TVP F F Head F Body Anterior Most ribs have 3 articulations with vertebrae: F = Facet Head of most ribs articulates with 2 facets on adjacent vertebrae Tubercle articulates with 1 facet on transverse process Rohen, Color Atlas of Anatomy 7e Ribs Attach to Sternum True ribs (1-7) Attach directly to sternum via their own costal cartilages Vertebrasternal ribs False ribs (8-10) Attach indirectly to sternum, via costal cartilages Vertebraochondrel or Vertebrocostal Gilroy, Atlas of Anatomy 3e 7.3 COA8e 4.7 Floating ribs (11-12) Do not attach to sternum vertebralribs rightbyyourkidneys Rib Attach by Synovial movement slight Joints we are protecting vital 1st Rib articulates with sternum organs Costovertebral joints near sternoclavicular (SC) joint I Rib → vertebrae 2nd Rib articulates at sternal angle Sternocostal joints Costal cartilages → sternum Sternum Costal cartilage Rib Sternocostal joint Vertebral body Costovertebral joints Tubercle of rib Rib Netter 2e Plate 180 Transverse process posterior Netter 6e Plate 184 Anterior Chest X-Ray (CXR) Rib 1 Rib FX Rib 2 Rib 3 Clinical Application Normal Rib 8 Rib 12 http://quickcareorer.com/wp-content/uploads/2014/09/broken-ribs-x-ray.jpg 10 between ribs Three Layers of Intercostal Muscles contractduringinhalation External intercostal for Elevate ribs important breathing Theypulltheribs Internal intercostal Depress ribs up contractduringforceexhalation 2 Innermost intercostal Depress ribs Intercostal muscles produce movement mainly during forced respiration. All three muscles “support” the intercostal space & stabilize chest wall Netter 7e Plate 197 Pivot of Ribs at Costovertebral & Sternocostal Joints Increases Thoracic Volume Elevation of upper ribs increases A-P dimension of thoracic cavity (pump handle mechanism) Treturn venousblood toheart Costovertebral joint QOrgin Isinsertation o o I I I External intercostal m. Contraction → rib elevation Internal intercostal m. Contraction → rib depression ECA 6e Fig. 4.7E Schuenke, Thieme Atlas of Anatomy 10.8E 12 Diaphragm The principle muscle of respiration 13 Diaphragm is Skeletal Muscle Muscular & tendinous parts voluntary t involuntarycontrol Diaphragm has three openings Peripheral muscle (costal & lumbar) Central tendon IVC AORTA Vertebral levels for the openings: T8 – T10 – T12 14 Superior Surface of the Diaphragm is Covered by Serous Membranes Superior view Anterior serousmembranethatcovers My theheart Pericardium covers the central diaphragm Pericardium Parietal pleura covers the peripheral diaphragm serousmembranethatcoverlungs Central tendon Serousmembrane 2 Layers bodywall Fluidbetween parietal visceral organ E Posterior 15 Phrenic Nerve Is Motor & Sensory Inn the diaphram Mediastinal pleura Phrenic n. PMS Sole motor supply (somatic efferent) Sensory (somatic afferent) to central pleura (thoracic) & peritoneum (abdominal) dermatome asstw cs Pericardium yotor sensory Note for Lab: Phrenic n. & pericardiacophrenic vessels pass between pericardium & mediastinal pleura Sensation to peripheral pleura & peritoneum provided by intercostal nerves 16 Blood Supply of the Diaphragm Main blood supply is from inferior (abdominal) surface Inferior phrenic aa. & inferior phrenic vv. IVC Inferior phrenic v. Inferior phrenic a. Aorta Superior surface Pericardiacophrenic & musculophrenic arteries (from internal thoracic) Superior phrenic arteries (from thoracic aorta) Lower intercostal vessels betweentheribs 17 Diaphragm is Main Muscle of Respiration muscle Inhalation requirescontraction Exhalation doesntrequire muscle contractic underquietbree Y normal Diaphragm contracts & flattens https://www.simplifiedsciencepublishing.com/ Diaphragm relaxes & domes Intercostal Spaces: Muscles & Segmental Neurovasculature 19 Three Layers of Intercostal Muscles Intercostal muscles are active mainly during forced respiration External intercostal m. Elevate ribs innoction Internal & innermost intercostal mm. Depress ribs Exhalation All three intercostal muscles “support” the intercostal space & stabilize the chest wall Netter 7e Plate 197 Segmental Intercostal Neurovasculature Neurovascular bundle in each intercostal space Between innermost & internal intercostal muscles Primary bundle courses in the costal groove, along the inferior margin of the rib Collateral branches extend to lower part of intercostal space External intercostal m. Internal intercostal m. Innermost intercostal m. Mnemonic for the typical order of neurovascular structures in the intercostal space: Posterior intercostal vein & artery Intercostal nerve Collateral nerve & vessels Superior-to-inferior: VAN – vein, artery, nerve Moore COA 8e 4.15 Intercostal Nerves Supply Thoracic Wall Formed by T1-T11 ventral rami and supply all structures of the anterolateral thoracic wall motorand sensory Dorsal (posterior) ramus I Inside-to outside: parietal pleura, intercostal muscles, ribs & skin 2 3 4 Three fiber types in these nerves: Somatic afferent (sensory) fibers Somatic efferent (motor) fibers Visceral efferent fibers (sympathetics)…sweat glands & arrector pili muscles skincoveringribs 3 Branches of which nerves supply the posterior thoracic wall? Ventral (anterior) ramus 22 I I Arteries of the Thoracic Wall Subclavian a. Mainly from aorta & subclavian Aorta → posterior intercostal Subclavian → internal thoracic → anterior intercostal Anterior & posterior vessels anastomose! Aorta Posterior intercostal a. Aorta Internal thoracic a. Anterior intercostal a. 23 Gilroy, Atlas of Anatomy 4e 7.17 Veins of the Thoracic Wall Brachiocephalic vv. superior vena cava Posterior intercostal veins drain to the azygos venous system Right → azygos vein Left → hemi-azygos or accessory hemi-azygos veins Anterior intercostal veins drain into the internal thoracic veins Drain into brachiocephalic veins Azygos v. Accessory hemi-azygos v. Internal thoracic vv. Hemi-azygos v. Gilroy, Atlas of Anatomy 4e 7.19A Internal Thoracic Vessels Internal thoracic arteries from subclavian Internal thoracic veins tributaries of brachiocephalic veins Internal thoracic (mammary) a. & v. Terminal branches of internal thoracic Musculophrenic → diaphragm Superior epigastric → upper anterior abdominal wall Anterior view Netter 7e D of portion superior Hollinshead’s Textbook of Anatomy diaphragm 25 Coronary Artery Bypass Graft (CABG) Internal thoracic (mammary) arteries used for coronary artery bypass grafts LITA or LIMA IT RITA or RIMA Clinical Application Right or left internal thoracic (mammary) arteries are abbreviated: The meanthesomethins oneinyour Until 1986, venous grafts (e.g., great me leg saphenous vein) were mostly used Studies have shown that internal thoracic or radial artery grafts have improved patency and survival f (compared to venous grafts) inyour arm Dimeling et al, 2021. CABG: When, why and how. CCJM 26 Test your Knowledge Which nerve(s) innervate the thoracic wall? A. B. C. D. E. Dorsal primary rami Intercostal Parasympathetic Sympathetic Vagus Which fiber type(s) are present in the nerves that innervate the thoracic wall? A. B. C. D. E. Somatic afferent Somatic efferent Visceral afferent Visceral efferent All of the above 27 Pleurae 28 Thoracic Cavity has Three Compartments serous Right & left cavities pleura membrane Pulmonary cavities (#7 & 8) Each contain a lung (lined by visceral pleura) Parietal pleura lines inside of pulmonary cavity Central cavity Mediastinum (#9) Heart Esophagus vessels Contains all other thoracic great Trachea structures 29 Moore COA Pleura Lines the Lungs & Lung Cavities Mesothelia line body cavities and exterior of their organs 1. Pleura (thoracic cavity) 2. Pericardium (around the heart) 3. Peritoneum (abdominal cavity) Pleura is a mesothelium Serous membranes secrete serous (watery) fluid that reduces friction between organs and facilitates movement between them. Mesothelium is a serous membrane made of simple squamous (flat) cells & connective tissue. simplesquamousepitheliumt producesthefluid by supported connective tiss e 30 Pleura and Pleural Cavities Pleural cavity: a potential space with negative pressure Moore COA Parietal pleura Lines inside of thoracic wall Subdivisions: costal, diaphragmatic, mediastinal, cervical Visceral pleura Adheres to outside of lung Pleural cavity Potential space between parietal & visceral pleura Contains a thin layer (1020mL) of pleural fluid w Lung & plurae T10spaceis negative Somatic afferents (touch & pain) from parietal pleura carried in intercostal & phrenic nerves Endothoracic Fascia Between costal parietal pleura and internal aspect of the thoracic cage (ribs & intercostal muscles) Provides a natural cleavage plane for surgical separation of costal pleura from the thoracic wall 32 Pleural Recesses Lungs do not completely fill pleural cavity…except during maximum inspiration Instead, in certain places the parietal pleura forms pockets, called recesses. Costomediastinal recess Posterior to sternum Costodiaphragmatic recess Around edge of diaphragm, where it meets the ribs These recesses exist in expiration and quiet breathing, but with deep inspiration the lungs enter them. 33 Schuenke Thieme Atlas Lungs, Plurae & Respiration Surface tension of pleural fluid keeps lungs in contact with the thoracic wall (like two pieces of glass with a film of water between). With inspiration Thorax expands and lung expands & fills with air Pleural fluid allows sliding to occur between parietal & visceral pleurae Visceral & parietal pleurae adhere…this draws lungs into recesses Expiration Lung Diaphragm more domed & costodiaphragmatic recess narrows Inspiration Expiration Lung Inspiration Lung borders at full expiration & inspiration Diaphragm flattens & costodiaphragmatic recess expands and lung “sucked into it” Schuenke Thieme Atlas Pleural Cavity and Pneumothorax Clinical Application During quiet breathing, pressure in pleural cavity is below atmospheric pressure (i.e., a vacuum) Introduction of air into the pleural cavity results in a pneumothorax, which results in a “collapsed lung”. Moore COA Chest Tube Placement Clinical Application A thoracostomy tube placed into the pleural cavity is used to remove fluid from pleural cavity (e.g., postop, pleurisy) and/or to restore the mechanical function of the lung (e.g., after a collapsed lung). Note: a thoracostomy tube is placed along the inferior edge of an intercostal space (ICS) in order to avoid damage to main neurovascular bundle, which courses along the superior edge of ICS. 36 https://link.springer.com/chapter/10.1007/978-3-319-91164-9_8 Thoracentesis Hydrothorax Congestive heart failure Hemothorax Wikipedia.org Complication of chest wound or central venous line placement Thoracentesis: Excess pleural fluid removed with a needle that is inserted through a lower intercostal space and into the costodiaphragmatic space cdn-prod.medicalnewstoday.com Clinical Application Excess fluid in pleural cavity usually accumulates in the costodiaphragmatic recess Tracheobronchial Tree 38 Trachea Has Two Parts 1. Cervical Larynx → thoracic inlet Larynx voicebox Cervical part cervical vertebra Thoracic part Thoracic 2. Thoracic Thoracic inlet → tracheal bifurcation Ends (divides) at the tracheal bifurcation, which is located at the level of the sternal angle vertebra R e Tracheal bifurcation Nielsen & Miller Trachea is Anterior to Esophagus edge I if ng Trachea lies anterior & adjacent to esophagus 1 Anterior Anterior Tracheal rings: C-shaped cartilage front Trachealis muscle forms posterior wall…adjacent to the esophagus Back side Posterior Trachea Esophagus Trachealis m. (skeletal muscle) (smooth muscle) constrictdial ate What is the functional significance of a thetrachea muscular (i.e., soft) posterior tracheal wall? forairmovement Trachealis muscle distends during swallowing and bulges into the lumen of the trachea to allow expansion of the esophagus when larger materials are swallowed Esophagus Carina of Trachea Carina (L. keel of a boat) is a midline ridge of cartilage at the lower end of the trachea; it divides the two main bronchi Coronal section of trachea and main bronchi Wikipedia Bronchoscopy view of tracheal carina Conti & Zammit, BMJ http://dx.doi.org/10.1136/bcr-2019-229579 Bronchial Tree 1. Main (primary) bronchi Right: wider, shorter, more vertical Right main bronchus Right upper lobe bronchus 2. Lobar (secondary) bronchi Right: upper, middle & lower 3lobe I obesof - Intermediate bronchus a common your ungs airway for middle & lower lobes Left: upper & lower recieves a Left upper lobe bronchus Intermediate bronchus Tracheal bifurcation Middle lobe bronchus Left lower lobe bronchus Right lower lobe bronchus 2 lobes 3. Segmental (tertiary) bronchi t 10 bronchopulmonary segments per lung Pyramidal - Apex toward root of lung; Base at pleural surface of lung Left main bronchus Schuenke Thieme Atlas Right Longsegments Aspiration of Foreign Bodies Clinical Application Aspirated foreign bodies most often (not always) lodge in the right main bronchus –it’s more vertical & wider Delage & Marquette 2010 Eur Respir Monogr 48:135-148 litfl.com brownemblog.com 43 Schuenke Thieme Atlas Terminal Bronchial Tree tree welosecartilage Segmental bronchus ↓ Bronchiole Conducting bronchioles ↓ Terminal bronchioles ↓ Respiratory bronchioles ↓ Alveolar sacs d gainmuscle conducting y Lung parenchyma t functional zone occurs exchang gas Segmental bronchus Cartilage in walls me Ifyouhaveash t They constrict Bronchiole No cartilage in walls Lung parenchyma Conducting bronchiole moreair Just Terminal bronchiole No goblet cells Respiratory bronchiole Alveolar sacs Lung Parenchyma Respiratory bronchioles functional port gasexchange Terminal bronchiole Elastic fibers Smooth muscle and elastic fibers Few alveoli Alveolar duct and sac Smooth muscle Alveolus Respiratory bronchioles No smooth muscle in walls ~300 million alveoli in adult lung (surface area ~150 m2 … about the size of a tennis court – 60’ x 120’) Alveolus is structural unit of respiration Alveolar sac b of cluster grape mysat tow maisgoin in Alveolar duct Alveoli singleairsac ducat Kierszenbaum, Histology heart Alveoli blood designated grisette Pulmonary a. Intrasegmental pulmonary arteries carry deoxygenated blood to capillary plexuses in walls of alveolar sacs & alveoli – where O2 & CO2 exchanged Bronchial a. Pulmonary v. F blood oxygenated Intrasegmental pulmonary veins carry oxygenated blood to the heart Bronchial arteries follow & supply bronchial tree; they also supply visceral pleura, which is drained by intrasegmental pulmonary veins. toleft side othe f neat Bronchial a. Lungs Bridge & Tipper 2017 CT Anatomy for Radiotherapy 47 Right Lung ECA 6e 4.17 Left lung Upper lobe Left Lung Upper lobe Cardiac notch Ob li qu Lingula e( ma jo Horizontal (minor) fissure r) f i liq Ob ue ajo (m r) e ur if ss ssu re Lower lobe Middle lobe 3 Lobes – 2 Fissures Lower lobe 2 Lobes – 1 Fissure Rohen Atlas Root vs. Hilum of the Lung Hilum Root Root of the lung Main bronchus Short (1-2 cm) tube of pleura Pulmonary a. Passage between mediastinum & lung Pulmonary v. Transmits main bronchus, pulmonary arteries & veins, bronchial arteries & nerves & lymphatics Hilum of the lung exitthelung istheopenning Opening on medial aspect of the lung (“doorway” to the lung) Has same structures as the root Pulmonary lig. (empty fold of pleura) Mediastinum Root Hilum (doorway) 49 Blood Supply of the Lungs grounded tolungs heart from O P D highlyoxgnated bloodfrom veinscarrying lungstoward heart oxygenatedblood Relationships in the Root of the Lung Pulmonary artery (A) anterior to main bronchus (B) Pulmonary artery (A) superior to main bronchus (B) Right lung Left lung Bronchial artery (really small) A Anterior B P A A B Posterior Posterior Anterior 51 Lymphatic Drainage of the Lungs 52 Lymph from Lungs Passes thru Hilar Nodes Superficial lymphatic plexus – subpleural plexus drains to hilar nodes 4 Deep lymphatic plexus – in submucosa of bronchi & peribronchial connective tissue Nodal Pathway secondary broncioflobes 3 y bronchi 1. Pulmonary nodes along lobar to 2. Bronchopulmonary (hilar) nodes close rootof long 3. Tracheobronchial nodes around tracheal bifurcation 2 1 Carinal nodes Hilar nodes Inferior tracheobronchial nodes = carinal nodes 4. Paratracheal nodes → lymph passes to bronchomediastinal lymph trunks (not the thoracic duct) Superficial (subpleural) lymphatic plexus Lymphnodesarealwaysin clusters 53 Thoracic Duct & Right Lymphatic Duct Final pathway: Major ducts that return lymph to the venous system rightympathic Thoracicduct Right lymphatic duct drains lymph from right upper quadrant of the body Right side – head, neck, thoracic wall & upper limb Thoracic duct drains lymph from remainder of the body Left side – head, neck, thoracic wall, upper limb Entire body below diaphragm Cisterna chyli Lymphatic Ducts & Trunks Two main ducts return lymph to left & right venous angles Thoracic duct Cisterna chyli (upper abdomen) → posterior mediastinum → left venous angle Right lymphatic duct Terminates at right venous angle Bronchomediastinal lymph trunks Drain thoracic viscera (e.g., lungs) before joining ducts Thoracic duct Test your Knowledge A 63-year-old man comes to the oncology clinic with a chronic cough and recent hemoptysis (coughing up blood). A patient history shows that he has been a pack-a-day smoker for 20 years. Bronchoscopy shows a widening of the trachea at its bifurcation and deformation of the carina. A PET CT-scan confirms bronchogenic carcinoma. Bronchoscopy view of tracheal carina Enlargement of which lymph nodes likely account for the airway alteration. A. B. C. D. E. Bronchopulmonary Paratracheal Pulmonary Subpleural Tracheobronchial Conti & Zammit, BMJ http://dx.doi.org/10.1136/bcr-2019-229579 56 Innervation of the Tracheobronchial Tree 57 Parasympathetics Anatomy Preganglionic fibers from brainstem via vagus nerve (CN X) Postganglionic cell bodies in intramural ganglia Function withintargetorgan Bronchoconstriction (stimulates bronchial smooth muscle) Vasodilation (inhibits pulmonary vascular smooth muscle) Secretomotor (stimulates bronchial & alveolar gland secretion) U Sympathetics Anatomy Preganglionic fibers from T4-T6 spinal cord Postganglionic cell bodies in ganglia of sympathetic trunks Function Bronchodilation (inhibits bronchial smooth muscle) Vasoconstriction (stimulates pulmonary vascular smooth muscle) Inhibits secretion from bronchial & alveolar glands Visceral Afferents Sensory information Most visceral afferents accompany vagal (CN X) fibers Unconscious: Reflexive sensation Bronchial mucosa (tactile sensations for cough reflexes) & bronchial muscle (stretch) Pulmonary arteries sensitive to BP; veins sensitive to blood gas Interalveolar connective tissue (HeringBreuer reflexes – limit respiratory excursions) Visceral pleura can detect stretch Conscious: Nociceptive (pain) sensation Pain fibers likely originate in spinal cord follow sympathetic fibers Pain from trachea, bronchi & visceral pleura…but NOT lung parenchyma J N J Vagus & Recurrent Laryngeal Nerves Vagus nerves pass through thoracic cavity Heart Right vagus n. E Create amap diagram Vagal branches to cardiac & pulmonary plexuses Left vagus n. mm Vagus nerves pass onto esophagus as esophageal plexus shanowing Left recurrent laryngeal n. Passes under aortic arch, posterior to ligamentum arteriosum Ligamentum arteriosum Right recurrent laryngeal n. Passes under right subclavian artery (RSA) Right recurrent laryngeal n. Esophageal plexus Left recurrent laryngeal n. 61 Cardiopulmonary Plexuses Nerves to bronchi & pleura via pulmonary plexuses (extensions of cardiac plexus) motor Fiber types included Vagus nerves Sympathetic, parasympathetic vagusnerve rings & visceral afferent Sympathetic chain Fensory Cardiac plexus is on trachea & bifurcation, aortic arch, pulmonary trunk, coronary vessels & SA node Pulmonary plexuses are on the bronchial tree 62 END 63