Anatomy of the Mediastinum Flashcards
What is the mediastinum, and where is it located?
The mediastinum is the central compartment of the thoracic cavity, located between the two pleural cavities.
How is the mediastinum anatomically divided?
It is divided into the superior and inferior mediastinum, with the inferior mediastinum further subdivided into anterior, middle, and posterior compartments.
What are the boundaries of the mediastinum?
The mediastinum is bounded superiorly by the thoracic inlet, inferiorly by the diaphragm, anteriorly by the sternum, and posteriorly by the thoracic vertebrae.
What structures are contained in the superior mediastinum?
The superior mediastinum contains the thymus, great vessels, trachea, esophagus, thoracic duct, vagus and phrenic nerves, and sympathetic trunks.
What are the main contents of the anterior mediastinum?
The anterior mediastinum contains the thymus (in children), fat, lymph nodes, and small blood vessels.
Which major structures are located in the middle mediastinum?
The middle mediastinum contains the heart, pericardium, ascending aorta, pulmonary trunk, and main bronchi.
What are the primary contents of the posterior mediastinum?
The posterior mediastinum contains the descending thoracic aorta, esophagus, thoracic duct, azygos and hemiazygos veins, and sympathetic trunks.
What is the clinical significance of the thymus in the anterior mediastinum?
The thymus is involved in immune function, and its enlargement (e.g., thymoma) can cause compression of mediastinal structures.
Which major blood vessels pass through the superior mediastinum?
The aortic arch and its branches (brachiocephalic trunk, left common carotid artery, and left subclavian artery) pass through the superior mediastinum.
What is the course of the vagus nerve in the mediastinum?
The vagus nerve descends in the superior mediastinum and gives rise to the recurrent laryngeal nerve before contributing to the cardiac, pulmonary, and esophageal plexuses.
How does the phrenic nerve traverse the mediastinum?
The phrenic nerve descends anterior to the lung hilum and supplies motor and sensory innervation to the diaphragm.
What is the role of the thoracic duct in the mediastinum?
The thoracic duct drains lymph from most of the body and empties into the junction of the left subclavian and internal jugular veins.
Where does the azygos vein system drain, and what is its mediastinal course?
The azygos vein drains blood from the posterior thoracic wall and empties into the superior vena cava.
What is the location and significance of the esophagus in the mediastinum?
The esophagus is located posterior to the trachea and anterior to the vertebral column in the superior and posterior mediastinum.
Which structures form the borders of the middle mediastinum?
The middle mediastinum is bordered by the anterior and posterior mediastinum and contains the heart and pericardium.
How is the pericardium related to the mediastinum?
The pericardium surrounds the heart and defines the central portion of the middle mediastinum.
What are the anatomical relations of the trachea in the mediastinum?
The trachea is located in the superior mediastinum, anterior to the esophagus, and bifurcates at the level of the sternal angle.
What is the carina, and where is it located in the mediastinum?
The carina is the ridge of cartilage at the bifurcation of the trachea at the level of the T4-T5 vertebrae.
How does the sympathetic trunk course through the mediastinum?
The sympathetic trunk runs bilaterally along the posterior mediastinum, giving rise to the splanchnic nerves.
What are the branches of the thoracic aorta in the posterior mediastinum?
The thoracic aorta gives off bronchial, esophageal, intercostal, and subcostal arteries in the posterior mediastinum.
What is the clinical significance of the aortic arch in the mediastinum?
The aortic arch gives rise to major arteries supplying the head, neck, and upper limbs and can be affected by aneurysms and atherosclerosis.
How do the left and right recurrent laryngeal nerves differ in their mediastinal course?
The right recurrent laryngeal nerve loops around the subclavian artery, while the left loops around the aortic arch.
What is the role of the bronchial arteries, and where do they originate?
The bronchial arteries arise from the thoracic aorta and supply oxygenated blood to the lungs and bronchi.
What lymphatic structures are found in the mediastinum?
The mediastinum contains numerous lymph nodes, including the tracheobronchial and paratracheal nodes.
How does the heart relate to the different divisions of the mediastinum?
The heart is located within the middle mediastinum and is enclosed by the pericardium.
What are the three major constrictions of the esophagus in the mediastinum?
The esophagus has three major constrictions: at the cricopharyngeal junction, where it is crossed by the aortic arch and left bronchus, and at the diaphragm.
What is the relationship of the thoracic duct to the surrounding structures in the mediastinum?
The thoracic duct lies between the aorta and the azygos vein, posterior to the esophagus.
How do tumors of the mediastinum present clinically?
Mediastinal tumors may cause symptoms such as dyspnea, dysphagia, or superior vena cava syndrome due to compression of adjacent structures.
What imaging modalities are commonly used to evaluate mediastinal structures?
Chest X-ray, CT scan, and MRI are commonly used to assess mediastinal structures.
What are the common causes of mediastinal widening seen on a chest X-ray?
Mediastinal widening can result from aortic aneurysm, lymphadenopathy, malignancy, or hemorrhage.
