CPR Lecture 1 - Mediastinum PDF

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All year-1 course materials, whether in print or online, are protected by copyright. The work, or parts of it, may not be copied, distributed, or published in any form, printed, electronic, or otherwise. As an exception, students enrolled in year 1 of St. George’s University School of Medicine and their faculty are permitted to make electronic or print copies of all downloadable files for personal and classroom use only, provided that no alterations to the documents are made and that the copyright statement is maintained in all copies. ‘View only’ files, such as lecture recordings, are explicitly excluded from download, and creating copies of these recordings by students and other users is strictly illegal. The author of this document has made the best effort to observe current copyright law and the copyright policy of St. George's University. Users of this document identifying potential violations of these regulations are asked to bring their concerns to the attention of the author.  Drake Richard L, Vogl A. Wayne Mitchell Adam W. M. Gray’s Anatomy for Students. 4th Ed. Printed Textbook: Chapter 3 pg. 130-131, 184-243 Online Textbook: Chapter 3 Regional Anatomy Mediastinum Anterior mediastinum Superior mediastinum Posterior mediastinum Please be sure to review the green ‘In the Clinic’ boxes for clinical correlations for this topic  Your Objectives will show here! SOM.MK.II.BPM1.3.CPR.2.ANAT.1363 Describe the subdivisions of the mediastinum and their boundaries. List the structures found in the superior, anterior, middle and posterior mediastinum and their relationships SOM.MK.II.BPM1.3.CPR.2.ANAT.1364 to one another. SOM.MK.II.BPM1.3.CPR.2.ANAT.1365 Describe the relationships of the esophagus, trachea and thoracic duct in the superior mediastinum. SOM.MK.II.BPM1.3.CPR.2.ANAT.1366 Describe the typical branching pattern of the aortic arch in the superior mediastinum. SOM.MK.II.BPM1.3.CPR.2.ANAT.1367 Describe the subclavian artery and its branches. SOM.MK.II.BPM1.3.CPR.2.ANAT.1368 Explain what clinical impairments could be used by the presence of a cervical rib SOM.MK.II.BPM1.3.CPR.2.ANAT.1369 Describe the relationships of the phrenic nerves to the aortic arch and the root of the lung. SOM.MK.II.BPM1.3.CPR.2.ANAT.1370 Describe the relationships of the vagus nerves to the aortic arch, the root of the lung and the esophagus. SOM.MK.II.BPM1.3.CPR.2.ANAT.1371 Describe the course of the right and left recurrent laryngeal nerves in the thorax. SOM.MK.II.BPM1.3.CPR.2.ANAT.1372 List the structures that are found at the plane of Ludwig. SOM.MK.II.BPM1.3.CPR.2.ANAT.1373 Describe the four normal constrictions of the esophagus. Describe the arterial supply, innervation, venous and lymphatic drainage of the thoracic and SOM.MK.II.BPM1.3.CPR.2.ANAT.1374 abdominal portions of the esophagus. SOM.MK.II.BPM1.3.CPR.2.ANAT.1375 Describe the azygos system of veins and their typical pattern of drainage. SOM.MK.II.BPM1.3.CPR.2.ANAT.1376 Describe the origin of the greater, lesser and least splanchnic nerves. SOM.MK.II.BPM1.3.CPR.2.ANAT.1377 List the normal openings in the diaphragm and their approximate vertebral level. SOM.MK.II.BPM1.3.CPR.2.ANAT.1378 Describe the anatomical location, mechanism and clinical consequences of thoracic duct laceration. SOM.MK.II.BPM1.3.CPR.2.ANAT.1379 Describe the clinical signs, causes and presentation of thoracic outlet syndrome  SOM.MK.II.BPM1.3.CPR.2.ANAT.1363 Mediastinum The thoracic compartment between the two pleural sacs. Contains the major organs of the thoracic cavity (heart, esophagus, trachea, major nerves, and major systemic blood vessels) Except the lungs Boundaries Superior: Superior thoracic aperture Inferior: Diaphragm Anterior: Sternum Posterior: Thoracic Vertebrae  SOM.MK.II.BPM1.3.CPR.2.ANAT.1372 It’s at the level of T4/T5 posteriorly and the second rib anteriorly. The Plane of Ludwig divides the mediastinum into superior and inferior divisions. Structures: Superior vena cava as it enters the pericardium Beginning and ending of the arch of the aorta Trachea bifurcation Pulmonary trunk bifurcation What are some other names for the plane of Ludwig? SOM.MK.II.BPM1.3.CPR.2.ANAT.1363  SOM.MK.II.BPM1.3.CPR.2.ANAT.1380 Superior mediastinum Arch of the aorta + its 3 branches, brachiocephalic veins, SVC, phrenic nerves, vagus nerves, left recurrent laryngeal nerve, thoracic duct, Thymus, trachea, esophagus, other small nerves, blood vessels, lymphatics. Anterior mediastinum Thymus, fat, connective tissue, lymph nodes, mediastinal branches of the internal thoracic vessels, sternopericardial ligaments. Middle mediastinum Pericardium, heart, origins of the great vessels, main bronchi. Posterior mediastinum Thoracic aorta + its branches, Azygos system of veins, esophagus + its nerve plexus, sympathetic trunks, thoracic splanchnic nerves, thoracic duct + lymph nodes. Arteries, Veins, nerves, lymphatics, other structures  SOM.MK.II.BPM1.3.CPR.2.ANAT.1363 SOM.MK.II.BPM1.3.CPR.2.ANAT.1365 Boundaries: Superior: 1st rib, T1, jugular notch Inferior: transthoracic plane Posterior: T1 – T4 Vertebrae Anterior: Manubrium Contents: Thymus*** Trachea Arch of the Aorta and branches Brachiocephalic veins Superior vena cava Esophagus*** Thoracic Duct*** Nerves***  SOM.MK.II.BPM1.3.CPR.2.ANAT.1364 Develops from the third pharyngeal pouch. Located in the anterior part of superior mediastinum, posterior to the manubrium. Upper part - extends into neck Lower part - extends into anterior mediastinum. Arterial supply: internal thoracic and anterior intercostal arteries. Venous drainage: into brachiocephalic, internal thoracic and inferior thyroid veins. Lymphatic drainage: into parasternal, brachiocephalic and tracheobronchial lymph nodes. What happens to the thymus after puberty?  SOM.MK.II.BPM1.3.CPR.2.ANAT.1365 Continuation from the larynx at C6. Lies anterior to the esophagus. Terminates at Plane of Ludwig. Bifurcates into right and left main bronchi. Crossed over by the arches of the aorta and the azygos vein.  SOM.MK.II.BPM1.3.CPR.2.ANAT.1366 Branches of the Aortic Arch: 1. Brachiocephalic trunk Right subclavian artery Right common carotid artery 2. Left common carotid artery 3. Left subclavian artery All three are crossed anteriorly by the left brachiocephalic vein What is the ligamentum arteriosum?  SOM.MK.II.BPM1.3.CPR.2.ANAT.1364 Formed by the union of the subclavian and internal jugular veins Located posterior to the sternoclavicular joints and the thymus. Clinically, the left brachiocephalic vein must cross the mid- line. ​Therefore, in a tracheotomy, you need to remember the left brachiocephalic vein is present there.  SOM.MK.II.BPM1.3.CPR.2.ANAT.1370 Brings parasympathetic and visceral afferent to the thoracic viscera. Contribute to the cardio-pulmonary plexuses. Each nerve divides into several branches that spreads over the structure forming the esophageal plexus. Just above the diaphragm these fibers converge to form two trunks: Anterior Vagal trunk: mainly from the left vagus nerve. Posterior Vagal trunk: mainly from the right vagus nerve.  SOM.MK.II.BPM1.3.CPR.2.ANAT.1371 Arise from vagus nerves on either side. Left recurrent laryngeal nerve hooks Right Recurrent Laryngeal around the ligamentum arteriosum, and, passing up on the right side of the aortic arch. Left Recurrent Laryngeal Right recurrent laryngeal nerve hooks around the right subclavian artery. Recurrent laryngeal innervates some of the intrinsic muscles of the larynx. If there is damage to this nerve, the patient can present with hoarseness or loss of voice. What is the function of the larynx?  SOM.MK.II.BPM1.3.CPR.2.ANAT.1369 Sensory innervation to the mediastinal pleura, fibrous pericardium, and the parietal layer of serous pericardium. Sensory and motor innervation to the diaphragm and its associated membranes.  SOM.MK.II.BPM1.3.CPR.2.ANAT.1368 Articulates posteriorly with vertebrae CVII and anteriorly with the superior border of the anterior aspect of rib I. Structures that normally pass over rib I are elevated by, and pass over, the cervical rib and band. Cervical ribs may produce thoracic Neck radiograph demonstrating bilateral cervical ribs (may look like outlet syndrome. horn like structures) What is the prevalence of cervical ribs?  SOM.MK.II.BPM1.3.CPR.2.ANAT.1379 Arterial compression and embolization: there may be atheroma and eventually distal embolization. Tension on the T1 nerve: the T1 nerve, which normally passes over rib I, is also elevated by the presence of a cervical rib; thus, the patient may experience a sensory disturbance Compression of the subclavian vein: this may induce axillary vein thrombosis. Note: Thoracic Outlet Syndrome can be caused by other conditions such as muscular abnormalities, trauma, tumors in that region.  SOM.MK.II.BPM1.3.CPR.2.ANAT.1363 Boundaries​ Superior: transthoracic plane Inferior: diaphragm Anterior: body of the sternum Posterior: T5-T12 Divisions:​ Anterior Middle Posterior  SOM.MK.II.BPM1.3.CPR.2.ANAT.1363 SOM.MK.II.BPM1.3.CPR.2.ANAT.1364 Boundaries:​ Anterior: sternum Posterior: pericardium Superior: Transthoracic plane Inferior: Diaphragm Contents:​ Thymus (or what remains) Lymph nodes Connective tissue  SOM.MK.II.BPM1.3.CPR.2.ANAT.1363 SOM.MK.II.BPM1.3.CPR.2.ANAT.1364 Boundaries: Bounded by the fibrous layer and parietal layer of serous pericardium on all sides. Pericardium is tightly adhered to the diaphragm inferiorly Contents:​ Heart Ascending aorta Intrapericardial SVC Pulmonary trunk Main bronchi  SOM.MK.II.BPM1.3.CPR.2.ANAT.1363 SOM.MK.II.BPM1.3.CPR.2.ANAT.1364 Boundaries:​ Anterior: Pericardium Posterior: Vertebrae T5-T12 Contents:​ Esophagus Esophageal plexus*** Descending thoracic aorta Azygos venous system Thoracic duct Sympathetic chain  SOM.MK.II.BPM1.3.CPR.2.ANAT.1373 SOM.MK.II.BPM1.3.CPR.2.ANAT.1374 Location: The continuation of the pharynx from C6 vertebral level Enters the thorax through the superior thoracic aperture Passes through the diaphragm at T10 level Ends where it enters the stomach at the cardiac sphincter Constrictions: 1. Junction with the pharynx (C6) - cricopharyngeal constriction 2. Crossed by arch of aorta and 3.left main bronchus (T4/5) 4.Passagethrough the diaphragm at the esophageal hiatus (T10)  SOM.MK.II.BPM1.3.CPR.2.ANAT.1374 Thoracic Portion: Arterial Supply: thoracic aorta & bronchial arteries Venous Drainage: azygos, hemiazygos veins Lymphatic Drainage: thoracic duct, posterior mediastinal nodes Innervation: esophageal plexus, sympathetic trunks Abdominal Portion: Arterial Supply: left gastric & left inferior phrenic arteries Venous Drainage: left gastric vein Lymphatic Drainage: left gastric nodes Innervation: vagal trunks, greater splanchnic nerves  SOM.MK.II.BPM1.3.CPR.2.ANAT.1375 Series of longitudinal vessels on each side of the body that drain blood from the body wall and move it superiorly to empty into the SVC. Form a collateral drainage pathway between the IVC and SVC. Azygous Hemiazygos Accessory hemiazygos Which vessels come together to form the azygous, hemiazygos and accessory hemiazygos veins?  SOM.MK.II.BPM1.3.CPR.2.ANAT.1378 Largest and most prominent lymphatic vessel in the body. Starts in the abdomen as confluence (cisterna chyli)​​. Passes through the diaphragm’s aortic hiatus​. Crosses midline at T5 to the left side of the thorax. Drain into the junction of left subclavian and left internal jugular veins. Carries lymph from the entire body except the right head and neck, right upper limb and right thorax.. Which lymphatic vessel drains the right head, neck, upper limb and thorax?  SOM.MK.II.BPM1.3.CPR.2.ANAT.1376 Sympathetic trunks are located laterally to the vertebral column Contain interconnected sympathetic ganglia Forms 3 distinct splanchnic nerves Greater, lesser and least Greater T5-9 with some variation Joins the celiac ganglion Lesser T10-11 Joins aortico-renal ganglion Least T12 but not always present Joins the renal plexus  SOM.MK.II.BPM1.3.CPR.2.ANAT.1378 Can be caused by: Pathology affecting lungs, great vessels, esophagus, spine, lymph nodes Penetrating trauma Catheterizations (e.g., internal jugular vein) Surgeries (e.g., esophagostomy) Presents with:​ Presence of chyle (fluid mixture of lipids, proteins, lymphocytes) Chylothorax Chylomediastinum Chylopericardium Why is the thoracic duct susceptible to medical interventions?  SOM.MK.II.BPM1.3.CPR.2.ANAT.1377 A thin musculotendinous structure that fills the inferior thoracic aperture and separates the thoracic cavity from the abdominal cavity. Separation between thorax and abdomen Has three openings at the following levels T8 = inferior vena cava (Right) T10 = esophagus (left) T12 = Aorta (midline) It is attached peripherally to the: Xiphoid process of the sternum Costal margin of the thoracic wall Ends of ribs 11 and 12 Ligaments that span across the structures of the posterior abdominal wall Vertebrae of the lumbar region