Mediastinum Anatomy PDF

Anatomy of Mediastinal structures Dr Abdalla A E Elamin RAKCOMS MEDIASTINUM  Outline  Definition of mediastinum  Plane of Ludwig (line through sternal angle & disc between T4 & T5)  Divisions of the mediastinum  Structures in the superior...

Anatomy of Mediastinal structures Dr Abdalla A E Elamin RAKCOMS MEDIASTINUM  Outline  Definition of mediastinum  Plane of Ludwig (line through sternal angle & disc between T4 & T5)  Divisions of the mediastinum  Structures in the superior mediastinum  Structures in the anterior, middle and posterior mediastinum  Relationship of structures in the mediastinum Pgs 87-93  Mediastinum The mediastinum is the central compartment of the thoracic cavity, between the two pulmonary cavities, It is covered on each side by mediastinal pleura and contains all the thoracic viscera and structures except the lungs.  Mediastinum The mediastinum: Extends from the sternum and costal cartilage anteriorly to the thoracic vertebrae posteriorly, and from the superior thoracic aperture to the inferior thoracic aperture (diaphragm)  Mediastinum A horizontal plane passing through the “PLANE sternal angle and the intervertebral OF disc between vertebrae T4 and T5 LUDWIG” separates the mediastinum into superior and inferior parts. The inferior mediastinum is further subdivided by the pericardium into Anterior part Middle part Posterior part  Inferior mediastinum Subdivided by the pericardium into Anterior mediastinum: lies between the sternum and the pericardium Middle mediastinum: occupied by the pericardium and heart Posterior mediastinum: lies between the pericardium and thoracic vertebrae  Superior mediastinum Superiorly: superior thoracic aperture Anteriorly: manubrium of the sternum Posteriorly: upper four thoracic vertebrae (T1 to T4) Inferiorly: transverse thoracic plane (Ludwig plane)  SUPERIOR MEDIASTINUM Thymic Remnants Left Common Carotid Artery (a branch Internal Thoracic Arteries, Veins from arch of aorta) and Lymphatics Left Subclavian Artery (a branch Brachiocephalic Veins connect to from arch of aorta) form SVC Trachea Superior Vena Cava (SVC) Esophagus Arch of the Aorta Thoracic Duct Brachiocephalic Artery at the right Vagus Nerves side. (a branch from arch of Left Recurrent Laryngeal Nerve aorta) Phrenic Nerves  R L A A P P  WHAT REALLY HAPPENS AT THE PLANE OF LUDWIG?  Azygos vein ends (drains into the superior vena cava)  Beginning and end of the arch of the aorta  Fibrous pericardium fuses to the great vessels  Trachea divides into left and right primary bronchi  Ligamentum arteriosum ( connecting the arch of the Aorta with the left pulmonary artery)  Left recurrent laryngeal nerve under the aortic arch  Superficial and deep cardiac plexuses  Some Relationships at plane of Ludwig Bronchi svc Arch of aorta Ligamentum arteriosum INFERIOR MEDIASTINUM ANTERIOR Remnants of the fetal thymus gland Internal Thoracic arteries, veins and lymphatics MIDDLE Heart and Pericardium Ascending Aorta Termination of Superior and Inferior Venae Cavae POSTERIOR Esophagus Primary Bronchi and associated lymph nodes Descending Aorta and its branches Thoracic Duct Azygos system of veins Thoracic Splanchnic Nerves  Aortic knuckle SVC Pulmonary Trunk/ RA left auricle LV Apex IVC RV  R L R L T5/T6  TRACHEA & ESOPHAGUS NECK Larynx Pharynx C6 SUPERIOR Trachea MEDIASTINUM Esophagus T4-5 POSTERIOR Esophagus MEDIASTINUM C3,4,5 Phrenic n. Descending Aorta CN X Vagus n.  Brachiocephalic Lt. common carotid Lt. subclavian Bronchial SUP. POST. Pg 89-90  Vagus Nerve R. Vagus L. Vagus Superior mediastinum Posterior Esophageal plexus (vagal & symp.) mediastinum Ant. Vagal trunk Pg 89-90  esophagus RV RA LV LA Thoracic aorta POSTERIOR MEDIASTINUM Azygos v. Pg 92 Vagus nn.  Lt. vagus n. Lt. recurrent Laryngeal n. ? (in tracheoesophageal groove) Ligamuntum SUPERIOR arteriosum MEDIASTINUM POSTERIOR MEDIASTINUM SYMPATHETIC CHAIN AZYGOS V.  S B A NAV AZ V  Highest Highest S Intercostal Intercostal V Superior Superior C Intercostal Intercostal Accessory Hemi- azygos AZYGOS Hemi-azygos Subcostal I + V Ascending C Thoracic Lumbar Duct Pg 93 Lymphatic drainage Pg 93  Right lymphatic duct Formed by union of right jugular, subclavian, and bronchomediastinal trunks Drains the right sides of the thorax, upper limb, head, and neck. Empties into the junction of the right internal jugular and subclavian veins.  Thoracic duct Begins in the abdomen at the cisterna chyli Passes through the aortic opening of the diaphragm Arches laterally over the apex of the left pleura, runs behind the left internal jugular vein. it receives the left jugular, subclavian and bronchomediastinal trunks empties into the junction of the left internal jugular and subclavian veins.  Esophagus The esophagus, which is 25cm long, extends from the level of the lower border of the cricoid cartilage at the level of the 6th cervical vertebra to the cardiac orifice of the stomach  Cervical part Course In the neck it commences in the median plane and deviates slightly to the left as it approaches the thoracic inlet.  relations :  Anteriorly :The trachea and the thyroid gland posteriorly : the 6th and 7th cervical vertebrae on either side: it is related to the common carotid arteries and the recurrent laryngeal nerves.  On the left side: it is also related to the subclavian artery and the terminal part of the thoracic duct  Thoracic part Course  traverses the superior and then the posterior mediastinum. it returns to the midline at T5 then passes downwards, forwards and to the left to reach the esophageal opening in the diaphragm (T10). Relations: Anteriorly, it is crossed by the trachea, the left bronchus (which constricts it), the pericardium (separating it from the left atrium) and the diaphragm. Posteriorly: thoracic vertebrae, the thoracic duct and azygos vein and its tributaries and, near the diaphragm the descending aorta. On the left side :left subclavian artery, aortic arch, left recurrent laryngeal nerve, thoracic duct and the left pleura On the right side: pleura and the azygos vein. Esophagus in the superior & posterior mediastinum  Abdominal part passing forwards through the opening in the right crus of the diaphragm, lie in the esophageal groove on the posterior surface of the left lobe of the liver, covered by peritoneum on its anterior and left aspects.  posteriorly is the left crus of the diaphragm.  Constrictions of the esophagus one at the level of the sixth cervical vertebra (where it begins)  one at the crossing of the left main bronchus one where it pierces the diaphragm, at the tenth thoracic vertebra. It has upper sphincter (anatomical sphincter) It has lower sphincter (physiological sphincter) Achalasia of esophagus: failure of relaxation of the inferior esophageal sphincter , resulting from degeneration of myenteric (Auerbach's) plexus in the esophagus. THANKS