The Mediastinum Flashcards
List the various compartments of the mediastinum.
The thoracic cavity can be divided into a superior mediastinum and an inferior mediastinum. The inferior has three compartments: anterior, middle and posterior.
What separates the superior mediastinum from the inferior mediastinum?
The invisible line drawn from the sternal angle back through T4/T5.
Define the sternal angle.
The intersection between the manubrium and the body of the sternum.
In a cross section thru the heart and pericardial sac, identify ALL of the layers that would be incised thru into the ventricle.
From outside in: fibrous layer of pericardium, serous layer of pericardium (parietal serous pericardium), percardial cavity (with pericardial fluid), the visceral serous pericardium (epicardium), the myocardium (muscle of the heart wall) and the endocardium (endothelial lining of the heart).
What are the two compartments (layers) of the pericardial sac?
The fibrous layer (outer) and the serous layer (inner).
Where does the pericardial sac attach superiorly and inferiorly?
Superiorly the pericardial sac blends with the adventitia of the great vessels (aorta, pulmonary trunk); inferiorly the sac blends with the fibrous central tendon of the diaphragm.
Name two serous pericardial-lined sinuses/recesses of the pericardial sac.
The transverse and oblique pericardial sinuses.
Why is the transverse pericardial sinus important clinically?
This site is used to pass ligatures through for tying off circulation during cardiac surgery when the heart is placed on bypass.
Where does parietal serous pericardium reflect onto the heart to become visceral serous pericardium (epicardium)?
at the base of the great vessels leaving the heart
What is the clinical implication of the fibrous component of the pericardial sac?
The fibrous outer layer gives the pericardial sac its tough, unyielding nature such that overproduction or escape of fluid into the sac will compress the heart rather than expand the sac causing the heart to eject smaller and smaller cardiac volumes (cardiac tamponade). The condition, if left untreated, is fatal.
List the 4 divisions of the circulatory system and the function of each?
Pulmonary - reoxygenation of blood; coronary - blood supply to the heart muscle; systemic - blood supply to the body; portal - screening of intestinal blood containing ingested materials.
Outline the route of the pulmonary circulation.
Blood returns deoxygenated to the right atrium, passes to right ventricle, passes through pulmonary trunk into pulmonary aa. out into lungs, reoxygenated in lung capillaries, leaves via the pulmonary vv. and is returned to the left atrium.
