Mediastinum PDF

THE MEDIASTINUM MEDIASTINUM central part of thoracic cavity covered by mediastinal pleura contains thoracic vicsera, MEDIASTINUM Organization of MEDIASTINUM Clinical Importance of Sternal Angle  bifurcation of trachea  azygos vein → SVC  ascending aorta→ arch of aorta→ descending aorta  2nd r...

THE MEDIASTINUM MEDIASTINUM central part of thoracic cavity covered by mediastinal pleura contains thoracic vicsera, MEDIASTINUM Organization of MEDIASTINUM Clinical Importance of Sternal Angle  bifurcation of trachea  azygos vein → SVC  ascending aorta→ arch of aorta→ descending aorta  2nd rib joins with the sternum  transverse plane between the superior & inf mediastinum Superior Mediastinum  posterior to the manubrium & anterior to the first four throcic verberae  its superior border is superior thoracic aperture  its inf border is transverse thoracic plane (sternal angle and IV disc of T4 and T5  laterally mediastinal pleura Superior Mediastinum  posterior to the manubrium & anterior to the first four throcic verberae  its superior border is superior thoracic aperture  its inf border is transverse thoracic plane (sternal angle and IV disc of T4 and T5  laterally mediastinal pleura Contents of Superior Mediastinum  thymus  right & left brachiocephalic v  left superior intercostal v  superior vena cava  arch of aorta with its three large branches  trachea  esophagus  phrenic nerves  vagus nerves  left recurrent laryngeal n  thoracic duct  other small vessels,nerves Thymus  lymphoid organ  located: neck, anterior part of superior mediastinum, inferior mediastinum Thymus  plays an important role  As puberty is reached the thymus begins to diminish  in the adult Right & Left Brachiocephalic Vein  formed by the union of internal jugular and subclavian veins posterior to the medial end of clavicle  left v crosses the midline  union of the both veins forms the SVC posterior to the lower border of right first costal cartilage Right Brachiocephalic Vein  vertebral  first posterior intercostal  internal thoracic vein Left brachiocephalıc vein  vertebral  first posterior intercostal  left superior intercostal  inferior thyroid  internal thoracic  thymic  pericardial Clinical note: In infants & children left brachiocephalic vein rises above the superior border of the manubrium therefore it is less protected Superior Vena Cava  terminates at the lower margin of the right third costal cartilage  receives: azygos vein, pericardial & mediastinal veins  SVC & IVC are oriented along the same vertical axis Arch of aorta & its branches  aorta has three parts arch,ascending and descending  ascending aorta emerges from the heart and then form the arch of aorta  from right to left: brachiocephalic trunk, left common carotid & left subclavian Brachiocephalic Trunk  at the level of the upper border of right sternoclavicular joint:  right subclavian  right common carotid  occasionally thyroid ima artery left common carotid & left subclavian artery Ligamentum arteriosum  in the superior mediastinum  fetal circulation ductus arteriosus  connects the pulmonary trunk to the arch of aorta & permits the blood to bypass the lungs during development trachea & esophagus  trachea is the midline structure that is palpable in the jugular notch  Posteriorly esophagus  crossed by the azygos vein on the right side & arch of aorta on the left side  bifurcation of trachea whereas esophagus continues Vagus nerve Superior mediastinum posterior to the: SC joint & brachiocephalic v as they pass through the thorax they→ parasympathetic innervation to the thorax & vicseral afferents from the organs(normal physiological processes & reflex activities) Right Vagus Nerve  enters the superior mediastinum between the right brachiocephalic v & brachiocephalic trunk  descends in a posterior direction toward the trachea  crossed by arch of azygos vein  posterior to the root of the right lung to reach the esophagus  → esophagus, cardiac plexus & pulmonary plexus Left Vagus Nerve between the left common carotid & left subclavian vein crosses the left side of arch of aorta Left Vagus Nerve at the inferior border of it→ left recurrent laryngeal n Left Vagus Nerve  left recurrent laryngeal n enters the groove between the trachea and esophagus  left vagus descends in a posterior direction passes posterior to the root of the left lung and to reach the esophagus in the posterior mediastinum Right phrenic nerve  enters the superior mediastinum posterior to the beginning of the right brachiocephalic vein  descends on the right side of the SVC Right phrenic nerve in the middle mediastinum it descends in the fibrous pericardum anterior to the root of the right lung The pericardiophrenic vessels accompany with the phrenic n & leaves the thorax by passing through the , diaphragm with the IVC Left phrenic nerve  enters the superior mediastinum posterior to the beginning of the left brachiocephalic vein  descends across the left lateral surface of arch of aorta  it has similar course with the right phrenic nerve in the middle mediastinum Left phrenic nerve  ıt leaves the thorax by piercing the diapragm near the apex of the heart Content of the Middle Mediastinum The heart and pericardium Ascending aorta Pulmonary trunk Pulmonary veins SVC Azygos vein (terminal part) Phrenic n. Cardiac plexus Bifurcation of trachea. Great vessels in the middle mediastinum Posterior Mediastinum Thoracic aorta Thoracic duct Posterior mediastinal lymph nodes Azygos, hemiazygos & Accessory hemiazygos veins Esophagus Esophageal plexus Thoracic sympathetic trunks Thoracic splanchnic nerves Thoracic Aorta lies posterior to the root of the left lung, pericardium, esophagus changes its name at the T12 Thoracic Aorta left two bronchial arteries Pericardial a Post intercostal a (3-11) Sup phrenic artery Esophageal a Mediastinal a Subcostal a Thoracic duct  the largest lymphtic channel  Posterior Mediastinum & Superior mediastinum Thoracic Duct Esophagus Posterior Mediastinal Lymph Nodes lies post to pericardium receives: esophagus, pericardium, diaphragm Azygos system of veins  Azygos vein: Ascending lumbar vein + subcostal vein  Right crus of Diaghram  Level of T4 venous arch anteriorly  SVC  Receives: Right sup intercostal vein, Right Pos intercostal, Hemiazygos, Accessory hemyazygos, Right bronchial vein Hemiazygos vein  left ascending lumbar v+ left subcostal v  Left crus of diaphgram  receives: inf three posterior intercostal v (9-11) inf esophageal v mediastinal Level of T9 Accessory hemiazygos vein  Receives: 4(5)-8 posterior intercostal v &left bronchial veins  Opens to the azygos level of T7 Clinical Importance If the IVC is blocked, venous blood drain into the SVC through the azygos v and hemiazygos vein Sympathetic Trunk  base of the skull-coccyx  22-23 ganglia  longitudinal and transverse fibers  union of the both side at the gang impar Preganglionic fibers (white ramus)  Fırst way, terminate at their corresponding ganglia  Second way Pregang fibers enter the ST without making synapse at their corresponding ganglia. These fibers either ascend in the trunk and make synapse at high level or descend in the trunk and make synapse at the lumbar or sacral ganglia Third way preganglionic fibers leave the trunk without making synapse therefore these fibers are mylinated they are seen as white;splanchnic nerves Splanchnic nerves  The fibers which pass through the 5th through 9th throcal sympathetic ganglia without making synapse called the greater splanchic nerve. Coeliac gang  T10-T11 lesser spl n aorticorenal  T12 least splan n renal plexus Superior Mediastinum- Anterior Mediastinum Thymus Superior Mediastinum  posterior to the manubrium & anterior to the first four throcic verberae  its superior border is superior thoracic aperture  its inf border is transverse thoracic plane (sternal angle and IV disc of T4 and T5  laterally mediastinal pleura Superior MediastinumMiddle Mediastinum Phrenic nerves Superior Vena Cava Superior Mediastinum  posterior to the manubrium & anterior to the first four throcic verberae  its superior border is superior thoracic aperture  its inf border is transverse thoracic plane (sternal angle and IV disc of T4 and T5  laterally mediastinal pleura Superior Mediastinum- Posterior Mediastinum Esophagus Thoracic Duct Vagus Middle Mediastinum-Posterior Mediastinum Azygos Vein Superior Mediastinum  posterior to the manubrium & anterior to the first four throcic verberae  its superior border is superior thoracic aperture  its inf border is transverse thoracic plane (sternal angle and IV disc of T4 and T5  laterally mediastinal pleura Superior Mediastinum  SVC  Brachiocephalic veins  Arch of aorta  Trachea  Esophagus  Thymus  Vagus nerve  Left recurrent nerve  Phrenic nerve Inferior Mediastinum  Anterior  Middle  Posterior Anterior Mediastinum  Remenants of thymus  Lymph nodes  Fat  Connective Tissue Middle Mediastinum  Pericardium  Heart  Roots of great vessels  Arch of azygos vein  Main bronchi Posterior Mediastinum  Esophagus  Thoracic aorta  Azygos and Hemiazygos veins  Thoracic Duct  Vagus nerve  Sympathetic trunks  Splanchnic nerves