Questions and Answers
Define the mediastinum.
It is the thoracic region between the two lungs, between the sternum and vertebrae. It houses the heart, great vessels, etc.
Where is the superior mediastinum?
Above the sternal angle.
Where is the inferior mediastinum?
Below the sternal angle.
What vertebrae is equivalent to the sternal angle?
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What is the landmark for the division between the superior and inferior mediastinum?
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Where is the arch of aorta?
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Where is the bifurcation of the trachea?
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Where is the bifurcation of the pulmonary trunk?
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Where is the ligamentum arteriosum?
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List the contents of the superior mediastinum, from anterior to posterior.
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What is the venous angle?
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The thymus is most active in __, producing __.
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What is involution?
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Where is the anterior mediastinum and what does it contain?
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Where is the middle mediastinum and what does it contain?
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Where is the posterior mediastinum and what does it contain?
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Describe the positioning of the esophagus in relation to the aorta.
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What is Boerhaave syndrome?
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Azygos system of veins are towards the __ side of the body, though often it is in the __.
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Where does the azygos vein receive its supply superiorly?
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Where does the azygos vein begin inferiorly?
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Where is the azygos vein in relation to the esophagus?
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Where do the hemiazygos system of veins cross?
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Where are hemiazygos veins usually found?
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The azygos vein receives drainage from the __ thoracic wall while the hemiazygos system drains the __ thoracic body wall.
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If there is an absence of the hepatic portion of the inferior vena cava, where does the IVC go?
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What lymph trunks drain into venous angles?
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Where does the thoracic duct drain exclusively into?
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What is a thoracic duct injury?
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What is a hiatus hernia?
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Study Notes
Mediastinum Overview
- The mediastinum is the thoracic region located between the lungs, sternum, and vertebrae, housing critical structures like the heart and great vessels.
Superior Mediastinum
- Located above the sternal angle.
- Contains crucial components such as the thymus, brachiocephalic veins leading to the superior vena cava (SVC), vagus nerves, the arch of the aorta, trachea, and esophagus.
Inferior Mediastinum
- Situated below the sternal angle, divided into anterior, middle, and posterior sections.
- The division between superior and inferior mediastinum is marked by the sternal angle (angle of Louis).
Anatomical Landmarks
- The sternal angle correlates with T4 vertebra.
- Important structures associated with the sternal angle include the arch of the aorta and the carina where the trachea bifurcates.
Anterior Mediastinum
- Positioned between the pericardium and sternum.
- Contains fatty tissue, lymph nodes, and the internal thoracic artery.
Middle Mediastinum
- Encloses the pericardial cavity, consisting of the pericardium, heart, ascending aorta, and pulmonary trunk.
Posterior Mediastinum
- Located posterior to the heart, housing the descending thoracic aorta, esophagus, thoracic duct, and azygos veins.
Esophagus Positioning
- The esophagus begins posterior to the aorta and trachea, remains medial as the aorta arches, and becomes anterior to the aorta at the diaphragm.
Thymus Gland
- Most active in children, producing T-lymphocytes.
- Involution occurs at puberty, with lymphocytes migrating away, leaving fatty tissue.
Azygos System of Veins
- Primarily located on the right side, receiving blood from the right thoracic wall while the hemiazygos system collects from the left.
- The azygos vein arises from the superior intercostal vein and starts at the junction of the subcostal vein and ascending lumbar vein, positioned posterior to the esophagus.
Mediastinitis and Boerhaave Syndrome
- Boerhaave syndrome commonly follows bulimia, leading to esophageal rupture, mediastinitis, and pneumomediastinum with potential sepsis, necessitating antibiotics.
Hemiazygos Veins
- Typically found on the far left side, they cross the midline around T8 to drain into the azygos vein.
Lymphatic Drainage
- Venous angles receive lymph trunks: bronchomediastinal, subclavian, and jugular.
- The thoracic duct drains exclusively into the left venous angle.
Thoracic Duct Injury
- Defined as leakage of lymph (chyle) following thoracic or neck surgery, potentially resulting in major nutritional deficiencies.
Hiatus Hernia
- Occurs when stomach portions breach the esophageal hiatus of the diaphragm, lying in the lower posterior mediastinum.
- Antacids can alleviate symptoms, but severe cases may require surgery, leading to conditions such as GERD and cancer.
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Description
Explore the anatomy of the mediastinum, which includes important structures located between the lungs, sternum, and vertebrae. This quiz covers the superior and inferior mediastinum, their divisions, and key anatomical landmarks such as the sternal angle. Test your knowledge on the critical components housed in this thoracic region.