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Questions and Answers
Which of the following nerves is not found in the posterior mediastinum?
Which of the following structures is common to both the superior and middle mediastinum?
Which of the following nerves passes through the 5th to 9th thoracic sympathetic ganglia without making a synapse?
Which of the following structures is not found in the anterior mediastinum?
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Which of the following nerves is a branch of the vagus nerve?
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At which level does the thoracic aorta change its name?
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Which of the following structures does NOT receive blood from the thoracic aorta?
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Which vein receives the lower three posterior intercostal veins?
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Where do the sympathetic trunks unite?
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What happens to venous blood if the IVC is blocked?
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What is the common course of the right and left phrenic nerves in the middle mediastinum?
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Which of the following nerves crosses the left side of the arch of aorta?
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What is the origin of the brachiocephalic trunk?
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Which of the following structures is NOT located in the superior mediastinum?
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Which of the following nerves is crossed by the arch of the azygos vein?
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Study Notes
Splanchnic Nerves
- Preganglionic fibers can either ascend in the trunk and make synapses at a high level or descend in the trunk and make synapses at the lumbar or sacral ganglia
- The third way is when preganglionic fibers leave the trunk without making a synapse, these fibers are myelinated and seen as white, known as splanchnic nerves
Splanchnic Nerves Classification
- Greater splanchnic nerve: fibers pass through the 5th to 9th thoracic sympathetic ganglia without making a synapse
- Lesser splanchnic nerve: T10-T11
- Least splanchnic nerve: T12, forms the renal plexus
Mediastinum
- Central part of the thoracic cavity
- Covered by mediastinal pleura
- Contains thoracic viscera, nerves, and vessels
Organization of Mediastinum
- Divided into three parts: superior, middle, and posterior mediastinum
Superior Mediastinum
- Posterior to the manubrium and anterior to the first four thoracic vertebrae
- Superior border: superior thoracic aperture
- Inferior border: transverse thoracic plane (sternal angle and IV disc of T4 and T5)
- Laterally: mediastinal pleura
- Contents:
- Thymus
- Right and left brachiocephalic veins
- Superior vena cava
- Arch of aorta with its three large branches
- Trachea
- Esophagus
- Phrenic nerves
- Vagus nerves
- Left recurrent laryngeal nerve
- Thoracic duct
Middle Mediastinum
- Contents:
- Pericardium
- Heart
- Roots of great vessels
- Arch of azygos vein
- Main bronchi
Posterior Mediastinum
- Contents:
- Esophagus
- Thoracic aorta
- Azygos and hemiazygos veins
- Thoracic duct
- Vagus nerve
- Sympathetic trunks
- Splanchnic nerves
Superior Vena Cava
- Terminates at the lower margin of the right third costal cartilage
- Receives: azygos vein, pericardial and mediastinal veins
Arch of Aorta and its Branches
- Aorta has three parts: arch, ascending, and descending
- Ascending aorta emerges from the heart and forms the arch of aorta
- From right to left: brachiocephalic trunk, left common carotid, and left subclavian
Brachiocephalic Trunk
- At the level of the upper border of the right sternoclavicular joint
- Branches: right subclavian, right common carotid, and occasionally thyroid ima artery
Vagus Nerve
- Superior mediastinum posterior to the SC joint and brachiocephalic vein
- Passes through the thorax, providing parasympathetic innervation to the thorax and visceral afferents from the organs
Phrenic Nerve
- Right phrenic nerve: enters the superior mediastinum posterior to the beginning of the right brachiocephalic vein
- Left phrenic nerve: enters the superior mediastinum posterior to the beginning of the left brachiocephalic vein
Thoracic Aorta
- Lies posterior to the root of the left lung, pericardium, and esophagus
- Changes its name at the T12 level
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Description
This quiz covers the sympathetic nervous system, including the pathways of preganglionic fibers and the role of splanchnic nerves.
