Mediastinum

Mediastinum

1. Superior

   • Borders
     • Thoracic inlet
     • Transverse thoracic plane
     • Lungs
   • Aortic arch (lying down)
     • Ascends behind sternum on the right, passes behind trachea and oesohpagus and to the left side. Arches over LEFT bronchus and LEFT pulmonary artery
     • Brachiocephalic trunk
       • R common carotid
       • R subclavian
     • L common carotid
     • L subclavian
   • Remnants of thymus
   • SVC
     • Brachiocephalic veins
       • IJV
       • Subclavians
       • R lymphatic duct
       • L superior intercostal vein
       • Thoracic duct (LEFT)
     • Azygous vein
   • RIGHT vagus nerve
     • descends between RIGHT common carotid and RIGHT subclavian arteries
     • RIGHT recurrent laryngeal
       • Branches off vagus and loops under RIGHT subclavian and ascends to larynx, running lateral to trachea
     • Posterior oesophageal plexus
     • Anterior cardiac plexus
     • RIGHT pulmonary plexus
   • LEFT vagus nerve
     • Descends between LEFT common carotid and LEFT subclavian arteries
     • LEFT recurrent laryngeal
       • Branches off vagus and loops underneath arch of aorta posterior to the ligamentum arteriosum, then ascends to larynx, running lateral and between trachea and oesphagus
     • LEFT pulmonary plexus
     • Anterior oesophageal plexus
     • Posterior cardiac plexus
   • Phrenic nerves
     • Descend anterolaterally to vagus nerves
   • Trachea
   • Oesophagus
     • Lies between trachea and vertebrae
     • Aortic constriction
       • At bifurcation of trachea/arch of aorta (T4)

2. Inferior

   • Borders
     • Transverse thoracic plane
     • Diaphragm
     • T5-T12
     • Lungs/ mediastinal pleura
     • Body of sternum
   • Remnants of thymus
     • Large in childhood, as lots of T cells maturing. Atrophies in adulthood

3. Middle

   • Borders
     • Pericardium
   • Heart
   • Parts of great vessels
   • Hilum of each lung
   • Phrenic nerves

4. Anterior

   • Borders
     • Body of sternum
     • Transverse thoracic plane
     • Anterior surface of pericardium
     • Diaphragm
     • Lungs/ mediastinal pleura
   • Remnants of Thymus
   • Fatty tissue
   • Sternal lymph nodes

5. Posterior

   • Borders
     • T5-T12
     • Posterior surface of pericadium
     • Transverse thoracic plane
     • Diaphragm
   • Thoracic aorta
     • Makes impression against left lung
     • Paired intercostal arteries
     • Bronchial branches
     • Oesophageal branches
     • Pericardial branches
     • Diaphragmatic branches
     • Pierces diaphragm
       • "behind" diaphragm so muscle does not constrict aorta. Level T12
   • Pulmonary arteries and veins
   • Azygos vein
     • Hemiazygos vein
       • Drains LEFT intercostal veins 8/9 - 12
     • Accessory hemiazygos vein
       • Drains LEFT posterior intercostal veins 4-7/8
     • Vertebral venous plexus
     • Mediastinal veins
     • Oesophageal veins
     • Bronchial veins
   • Thoracic duct
     • Posterior to oesophagus
   • Oesophagus
     • Diaphragmatic constricton
   • Vagus nerves
     • Posterior trunk
     • Anterior trunk
   • Thoracic splanchnic nerves
     • Greater
       • T5-T9 = foregut sympathetic innervation
     • Lesser
       • T10-11 = midgut sympathetic innervation
     • Least
       • T12 = hindgut sympathetic innervation
   • Diaphragm