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Questions and Answers
Which structure is exclusively found in children within the superior mediastinum?
What is the role of the thymus in the immune system?
Which of the following structures does NOT pass through the superior mediastinum?
Which of the following nerves is located in the superior mediastinum?
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What marks the inferior boundary of the superior mediastinum?
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Which statement accurately describes the Brachiocephalic veins?
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What does the Superior Vena Cava primarily return blood from?
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Where does the Superior Vena Cava enter the heart?
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Which of the following arteries branches from the arch of the aorta?
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Which part of the aorta is located within the middle mediastinum?
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Study Notes
Superior Mediastinum
- The region in the thoracic cavity superior to the transverse thoracic plane
- Bounded by the superior thoracic aperture, manubrium sterni, upper thoracic vertebrae and the transverse thoracic plane
- Contains vital structures including veins, arteries, nerves, trachea, esophagus, and the thymus (only in children)
Veins
- Brachiocephalic Veins (Right & Left): Formed by the union of the internal jugular and subclavian veins, located posterior to the sternoclavicular joints.
- The left brachiocephalic vein is longer than the right and crosses the midline to the right side of the body
- Superior Vena Cava (SVC): Returns blood from all structures above the diaphragm (except the lungs and heart), formed by the union of the two brachiocephalic veins
- Located posterior to the inferior border of the 1st right costal cartilage, ending at the level of the 3rd right costal cartilage where it enters the right atrium of the heart
- Situated anterior to the trachea in the superior mediastinum
Arteries
- Arch of the Aorta: Curved continuation of the ascending aorta into the superior mediastinum, loops over the root of the left lung
- Starts posterior to the 2nd right costal cartilage, arches superior and posterior to the left
- Reaches its apex on the left side of the trachea and esophagus
- Terminates on the left side of the IV disc of T4/T5 vertebrae
- Gives rise to three branches:
- Brachiocephalic trunk: Largest and first branch of the aortic arch, arises between the trachea and the left brachiocephalic vein, ascends superolateral to the right side of the body, terminates posterior to the right sternoclavicular joint by dividing into the right common carotid and right subclavian arteries
- Left Common Carotid Artery: Second branch of the aortic arch, arises posterior to the left brachiocephalic trunk, begins anterior to the trachea, then on its left side, enters the neck by passing posterior to the left sternoclavicular joint
- Left Subclavian Artery: Third and most posterior branch of the arch, arises to the left of the trachea, leaves the chest posterior to the left sternoclavicular joint
- Loops over the superior surface of the 1st rib, below the clavicle, and posterior to the scalenus anterior muscle to enter the upper limb
- Becomes the axillary artery at the outer border of the 1st rib
Thymus
- The primary lymphoid organ responsible for T-lymphocyte maturation and immunocompetence
- Undergoes involution after puberty, eventually being replaced by fat in adulthood
Ligamentum Arteriosum
- A remnant of the fetal ductus arteriosus, which shunted blood from pulmonary arteries to the aorta in the fetus
- Obliterated within a few days of birth to become the ligamentum arteriosum
- Connects the inferior surface of the aortic arch to the root of the left pulmonary artery
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Description
This quiz covers the anatomy of the superior mediastinum, including its boundaries and the vital structures it contains. Focus areas include the brachiocephalic veins and the superior vena cava, detailing their formations and anatomical relationships. Test your knowledge on the significant components found in this critical region of the thoracic cavity.
