Thorax: Mediastinum Overview Flashcards
Mediastinum Superior Boundary
- Superior thoracic aperture (thoracic inlet)
Mediastinum Inferior Diaphragm
- Diaphragm
Mediastinum Anterior Boundary
- Sternum and costal cartilages (costal pleura)
Mediastinum Posterior Boundary
- Vertebral bodies of T1-12
Mediastinum Lateral Boundary
- Mediastinal pleura
Transverse Thoracic Plane
- Manubriosternal joint > T4/5 disc
- Divides superior (purple) and inferior (rest of the colors) mediastinum
Superior Mediastinum
- Superior to transverse thoracic plane
Inferior Mediastinum
- inferior to transverse thoracic plane
- Includes anterior, middle, and posterior mediastinum
Superior Mediastinum
- Thoracic inlet to transverse thoracic plane
- Between manubrium and T1-4
Content of Superior Mediastinum
- Thymus (most anterior)
- Brachiocephalic veins (posterior to thymus)
- SVC (superior portion)
- Aortic arch
- Brachiocephalic artery (trunk)
- Left Subclavian artery
- Left common carotid artery
Superior Mediastinum Nerves
- Left and right vagus
- Left recurrent laryngeal
- Left and right phrenic
- Cardiac plexuses
- Trachea
- Esophagus
- Thoracic duct
- Sternothyroid and sternohyoid muscles
Thymus
- Lymphoid organ
- Superior and anterior mediastinum
- Can extend above thoracic inlet
- Most anterior structure in the mediastinum
- Mostly replaced by fat by adulthood
Trachea
- Passes through thoracic inlet
- Begins and level of C6 and ends at sternal angle (not found in the inferior mediastinum)
Esophagus
- Passes through thoracic inlet
- Begins at level of C6, passes through diaphragm at level of T10
- Between trachea and vertebral column
- Also found in posterior mediastinum
Brachiocephalic Veins
- Pass through thoracic inlet
- Formed by union of jugular and subclavian veins (posterior to SC joint)
- Blood from head, neck, upper extremity
- Left is longer, more horizontal
- Anterior to the aortic arch branches
Tributaries
- IJV
- Subclavian veins
- Internal thoracic veins
- Inferior thyroid vein(s)
- Vertebral veins
- Supreme (highest) intercostal vein
- Accessory hemiazygos vein
Superior Vena Cava (Superior Portion)
- Union of brachiocephalic veins
- Spans 1st > 3rd costal cartilage (also in the middle mediastinum)
Tributaries
- Veins
Branches
- Arteries
Azygous
- Candy cane structure on the right side of the heart
Hemiazygous
- Located on left side
Aorta
- Ascending
- Arch
- Thoracic descending
Ascending Aorta
- Middle mediastinum
- Aortic valve to sternal angle
- Branches: left and right coronary
Arch of the Aorta
- Superior mediastinum
- Begins and ends at sternal angle
- Branches: brachiocephalic trunk, left common carotid artery, subclavian artery