Mediastinum and heart Flashcards
What is the corresponding vertebral level of the angle of Louis (angle of the sternum)?
Between T4-T5
- ) What are the superior, inferior, and lateral boundaries of the mediastinum?
- ) What is the dividing line between the superior and inferior mediastinum?
1.) Superior: Superior thoracic aperture
Inferior: Diaphragm
Lateral: Pleural cavities Mediastinum does NOT contain the lungs
2.) The angle of Louis (angle of the sternum), T4-T5
What are the divisions of the inferior mediastinum? What are the dividing landmarks?
Anterior: The area between the sternum and the pericardium.
Middle: The heart and pericardium.
Posterior: The area between the pericardium and the vertebral bodies.
- ) What are the boundaries of the superior mediastinum?
2. ) What are the contents of the superior mediastinum (11)?
1.) Superior: Thoracic inlet (upper opening of the thorax)
Inferior: Transverse thoracic plane (line from the sternal angle of Louis to the junction of T4-T5).
Lateral: Pleurae
Anterior: Manubrium
Posterior: First FOUR thoracic vertebrae.
2.) Superior vena cava (SVC), brachiocephalic veins, arch of the aorta, thoracic duct, trachea, esophagus, vagus nerve, left recurrent laryngeal nerve, phrenic nerve, and the thymus.
- ) What are the boundaries of the anterior mediastinum?
2. ) What are the contents of the anterior mediastinum?
1.) Anterior: Sternum
Posterior: Pericardium
Lateral: Pleurae
Anterior: Left transversus thoracis and the 4th, 5th, 6th, and 7th left costal cartilages.
2.) Thymus (lies anterior to the pericardium), loose areolar tissue, lymphatic vessels, 2-3 anterior mediastinal lymph nodes, small mediastinal branches of the INTERNAL MAMMARY ARTERY (mediastinal arteries).
- ) What are the boundaries of the posterior mediastinum?
2. ) What are the contents of the posterior mediastinum (7)?
1.) Anterior: Pericardium
Posterior: T5 (lower border) to T12
Superior: Transverse thoracic plane
Inferior: Thoracic surface of the diaphragm
Lateral: Mediastinal pleura (on either side)
- ) Thoracic part of the descending aorta (aka thoracic/descending aorta = synonymous), azygos vein, hemiazygos vein, accessory hemiazygos vein, vagus nerve, splanchnic nerve (not the sympathetic chain?????), esophagus, thoracic duct, some lymph glands.
* Mnemonic: DATES –> Descending aorta, Azygos vein and hemiazygos and accessory hemiazygos vein, Thoracic duct, Esophagus, Splanchnics.
Name the PAIRED branches of the descending thoracic aorta in descending order (5)
Bronchial branches, mediastinal branches, esophageal branches, pericardial branches, superior phrenic (supplies the diaphragm) arteries.
On which sides of the body are the azygos and hemiazygos veins, respectively?
Azygos = right side Hemiazygos = left side
What carries the lymphatics from the lower portion of the body. Describe its course and where it empties.
Thoracic duct. It is a posterior mediastinal and midline structure. It travels up the midline with the azygos vein, then veers LEFT and empties into the LEFT VENOUS ANGLE (p.170 Moore).
What muscle and cartilage marks the beginning of the esophagus? What structure does that muscle form?
Muscle: Cricopharyngeus muscle, it forms the superior/upper esophageal sphincter (UES)
Cartilage: Cricoid cartilage
- ) What do the splanchnic nerves supply?
2. ) What are the three branches located in the posterior mediastinum and where are they?
- ) Sympathetic innervation to the abdominal organs.
2. ) Greater splanchnic (T5-T9), lesser splanchnic (T10-T11), least splanchnic (T12)
What are the contents of the middle mediastinum (6)?
Heart, pericardium, phrenic nerves, roots of the great vessels (aorta, pulmonary arteries and veins, and vena cava), arch of the azygos vein, and main bronchi.
- ) What attaches the heart to the diaphragm?
2. ) What attaches the heart to the posterior surface of the sternum?
- ) Pericardiacophrenic ligament, which arises from the fibrous pericardium.
- ) Sternopericardial ligaments
What are the two subdivisions of the serous pericardium? What is between them?
Parietal and visceral (epicardium) pericardium. They are separated by the PERICARDIAL CAVITY which contains pericardial fluid.
What is the location and purpose of endocardium?
It is the innermost serous lining of the heart. It covers the chambers of the heart and lines the four valves of the heart.
Are any of the pericardial layers sensitive to pain? If so, which?
Yes. The fibrous and parietal pericardium and sensitive to pain. The visceral pericardium can feel STRETCHING, but not pain.
What is the location of the transverse pericardial sinus?
Oblique sinus?
Within the pericardial cavity, it lies between the superior vena cava (SVC) posteriorly, and the ascending aorta and pulmonary trunk anteriorly.
The oblique sinus, also within the pericardial cavity, lies between the pulmonary veins and the inferior vena cava (IVC).
What provides blood supply to the pericardium? From where do these vessels arise?
Pericardiacophrenic vessels (to pericardium and diaphragm) –> artery and vein.
The pericardiacophrenic artery arises from the internal thoracic artery, the vein arises from the brachiocephalic vein.
What supplies pain sensation to the pericardium?
The phrenic nerve
What major structure of the heart is not visible anteriorly in situ?
Left atrium
List which chambers of the heart form each surface:
- ) Right pulmonary surface
- ) Left pulmonary surface
- ) Sternocostal (anterior) surface
- ) Diaphragmatic (inferior) surface
- ) Right atrium
- ) Left ventricle
- ) Right ventricle
- ) Left ventricle and part of the right ventricle
How do you know that you are looking at the left atrium?
Four pulmonary veins are visible.