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Questions and Answers
What is the primary function of the right lymphatic duct?
What is the primary function of the right lymphatic duct?
At which vertebral level does the esophagus begin?
At which vertebral level does the esophagus begin?
Which structure is related to the esophagus anteriorly in the neck?
Which structure is related to the esophagus anteriorly in the neck?
What structures are located in the superior mediastinum?
What structures are located in the superior mediastinum?
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Which of the following structures primarily traverses the posterior mediastinum?
Which of the following structures primarily traverses the posterior mediastinum?
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Which trunk contributes to the formation of the right lymphatic duct?
Which trunk contributes to the formation of the right lymphatic duct?
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Which artery is a branch from the arch of the aorta located in the superior mediastinum?
Which artery is a branch from the arch of the aorta located in the superior mediastinum?
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What distinguishes the anterior, middle, and posterior mediastinum?
What distinguishes the anterior, middle, and posterior mediastinum?
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Which part of the inferior mediastinum is occupied by the heart and pericardium?
Which part of the inferior mediastinum is occupied by the heart and pericardium?
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Which of the following is NOT found at the plane of Ludwig?
Which of the following is NOT found at the plane of Ludwig?
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What is the inferior boundary of the superior mediastinum?
What is the inferior boundary of the superior mediastinum?
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What is the approximate length of the esophagus?
What is the approximate length of the esophagus?
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What structures does the thoracic duct drain?
What structures does the thoracic duct drain?
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Which of the following structures is NOT found in the superior mediastinum?
Which of the following structures is NOT found in the superior mediastinum?
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At which thoracic vertebra does the esophagus return to the midline?
At which thoracic vertebra does the esophagus return to the midline?
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Which of the following best describes the location of the anterior mediastinum?
Which of the following best describes the location of the anterior mediastinum?
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Which vein does the thoracic duct drain into at its terminus?
Which vein does the thoracic duct drain into at its terminus?
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Which artery is associated with the left pulmonary artery?
Which artery is associated with the left pulmonary artery?
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What part of the mediastinum contains the heart and pericardium?
What part of the mediastinum contains the heart and pericardium?
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Which structure in the superior mediastinum connects to form the superior vena cava?
Which structure in the superior mediastinum connects to form the superior vena cava?
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Which nerve provides innervation to the diaphragm?
Which nerve provides innervation to the diaphragm?
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Which structure is primarily associated with the left recurrent laryngeal nerve?
Which structure is primarily associated with the left recurrent laryngeal nerve?
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What does the azygos vein drain into?
What does the azygos vein drain into?
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Where does the trachea divide into left and right primary bronchi?
Where does the trachea divide into left and right primary bronchi?
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Study Notes
Mediastinum
- The mediastinum is the central compartment of the thoracic cavity, located between the two pulmonary cavities.
- It is covered by mediastinal pleura and contains all the thoracic viscera and structures except the lungs.
- Extends from the sternum and costal cartilage anterior ly to the thoracic vertebrae posteriorly, from the superior thoracic aperture to the inferior thoracic aperture (diaphragm).
Plane of Ludwig
- A horizontal plane passing through the sternal angle and the intervertebral disc between vertebrae T4 and T5 separates the mediastinum into superior and inferior parts.
Divisions of the Mediastinum
-
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)
-
Inferior mediastinum
- Subdivided by the pericardium into:
-
Anterior
- Lies between the sternum and the pericardium
-
Middle
- Occupied by the pericardium and heart
-
Posterior
- Lies between the pericardium and thoracic vertebrae
-
Anterior
- Subdivided by the pericardium into:
Structures in the Superior Mediastinum
- Thymic remnants
- Internal thoracic arteries, veins, and lymphatics
- Brachiocephalic veins connecting to form the superior vena cava (SVC)
- Superior vena cava (SVC)
- Arch of the aorta
- Brachiocephalic artery on the right
- Left common carotid and left subclavian arteries
- Trachea
- Esophagus
- Thoracic duct
- Vagus nerves
- Left recurrent laryngeal nerve
- Ligamentum arteriosum
Structures in the 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
Azygos System of Veins
- Azygos veins collect blood from the posterior thoracic wall and the abdomen.
- Veins in this system include:
- Highest Intercostal veins
- Superior Intercostal veins
- Accessory Hemiazygos vein
- Hemiazygos vein
- Subcostal vein
- Ascending Lumbar vein
- Azygos vein, which drains into the superior vena cava
Lymphatic Drainage
-
Right lymphatic duct
- Formed by the union of the 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
- Receives the left jugular, subclavian, and bronchomediastinal trunks
- Empties into the junction of the left internal jugular and subclavian veins
Esophagus
-
Cervical Part
- In the neck, it deviates slightly to the left as it approaches the thoracic inlet
- Relations:
- Anteriorly: trachea and thyroid gland
- Posteriorly: 6th and 7th cervical vertebrae
- On either side: common carotid arteries and recurrent laryngeal nerves
- On the left: subclavian artery and the terminal part of the thoracic duct
-
Thoracic part
- Traverses the superior and then the posterior mediastinum.
- Returns to the midline at T5, then passes downwards, forwards and to the left
- Reaches the esophageal opening in the diaphragm (T10).
Structures 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
Esophagus and Trachea Relationship
- The trachea and esophagus run parallel to each other, with the trachea anterior to the esophagus in the neck and superior mediastinum.
- The esophagus passes behind the trachea in the posterior mediastinum.
Vagus nerve
- Runs in the superior and posterior mediastinum.
- The left vagus nerve (cranial nerve X) forms the anterior vagal trunk, while the right vagus nerve forms the posterior vagal trunk.
- The vagus nerves contribute to the esophageal plexus, which controls the function of the esophagus.
Phrenic Nerves
- Travel through the superior mediastinum to reach the diaphragm.
- The phrenic nerves are responsible for controlling the diaphragm.
Relations of Structures in the Posterior Mediastinum
- Thoracic aorta runs posterior to the esophagus.
- Azygos vein runs on the right side of the vertebral bodies.
- Thoracic duct runs on the left side of the vertebral bodies.
- The right vagus nerve runs on the right side of the esophagus, and the left vagus nerve runs on the left side of the esophagus.
Additional Information
- The bronchi are located in the posterior mediastinum, branching from the trachea.
- The heart is located in the middle mediastinum, within the pericardium.
- The thymus gland is located in the anterior mediastinum.
- The superior vena cava (SVC) and inferior vena cava (IVC) terminate in the right atrium of the heart.
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Description
Explore the anatomy and divisions of the mediastinum, the central compartment of the thoracic cavity. Understand the significance of the plane of Ludwig and how the mediastinum is divided into superior and inferior parts. This quiz will test your knowledge of thoracic structures and their locations.