Flashcards in Lecture 8 DA Deck (24):
What seperates the superior and inferior mediastinum?
The plane of Louis at the sternal angle (T4-5)
Describe the pathway taken by the arch of the aorta.
It arches posterior, and to the left, towards the vertebral spine.
The inferior mediastinum can be further subdivided. What are they and where are they found?
Posterior mediastinum - Between the heart and the spine.
Middle mediastinum - The heart and its immediate structures.
Anterior mediastinum - Between the heart and sternum.
What is the thymus, and where is it located?
It is a gland important for immunity in pre-puberescent children, but becomes redundant at teen years and onwards. It is found at the arch of the aorta.
Which of the vessels in the mediastinum is most superficial?
Which two branches form the superior vena cava?
The left and right brachiocephalic veins.
Are the left and right brachiocephalic veins symmetric? Explain why.
The left is longer, as the superior vena cava is on the right side of the heart.
What two branches form the brachiocephalic veins?
The jugular and subclavian veins (left and right each).
Describe the branches of the arch of the aorta.
The ascending aorta is found at the plane of Louis, and branches into the brachiocephalic artery, which branches into the right subclavian and right common carotid arteries. There is no left brachiocephalic artery, the left common carotid and left subclavian branch straight off the arch (carotid branches first, followed by subclavian).
Where are the phrenic nerves in relation to the vagus nerves?
They are lateral to the vagus nerves.
What is the recurrent laryngeal nerve? What is the clinical significance behind it?
The left vagus nerve travels over the arch of the aorta, and as it does so, it gives off a branch that hook under the arch and back up to the larynx. It is close to ligamentum arteriosum. For this reason, it can often be mistaken for a patent ductus arteriosus (an unclosed ductus arteriosus), and during an operation to close it off if it hasn't done so, the recurrent laryngeal nerve can accidentally be sutured tight, affecting the patients voice.
Where are the phrenic and vagus nerve in relation to the heart?
The phrenic nerve is found on either side of the heart, and the vagus nerve is just medial to it.
Where does the thoracic duct drain to?
It enters at the origin of the left brachiocephalic vein, before the vein branches into jugular and subclavian veins.
What do the anterior, middle and posterior mediastinum of the inferior mediastinum contain?
Anterior - Fat, lymph nodes, internal thoracic/mammary artery and inferior thymus (in children).
Middle - Superior vena cava, heart, phrenic nerve, pulmonary trunk, and aorta.
Posterior - Thoracic duct, vagus nerve, thoracic aorta and oesophagus.
How do the oesophagus and thoracic aorta travel relative to each other?
The oesophagus travels left to reach the stomach. Thoracic aorta travels right. Eventually, the two cross over.
Where does the thoracic duct run?
It runs on the right of the midline. At the plane of Louis, it veers left towards the left brachiocephalic vein.
What does the thoracic aorta give off as it travels down?
It gives off segmental branches, known as the posterior intercostal arteries.
Where does the oesophagus receive its blood supply?
It receives it from the aorta, which gives off oesophageal branches as it travels down with it.
Where do bronchial arteries originate, and what do they supply?
They branch off of the aorta, close to the trachea bifurcation.
Describe the muscles and shape of the oesophagus.
The oesophagus has 3 muscle layers. They are striated in the upper part, smooth in the lower part, and the middle is a mix of the two.
It is flattened in the anteroposterior direction -> ( _ )
Which duct does all lymph below the diaphragm drain?
What is the cisterna chyli?
It is found in 20% of individuals, and if found inferior to the diaphragm, giving off the thoracic duct.
Where does the upper right quadrant of the body drain to?
To the Right lymphatic duct. Everywhere else drains to the left thoracic duct.