Mediastinum and Heart Flashcards
What is the mediastinum?
it forms a mobile midline between the two lungs and their pleural cavities
All structures within the mediastinum are held together by what?
held loosely together by connective tissue
How is the mediastinum divided into superior and inferior divisions?
A line drawn from the junction of the manubrium and body of the sternum (sternal angle) posteriorly between the bodies of T4 and T5
The inferior mediastinum is further divided into what?
3 more divisions; anterior, middle, and posterior
What is the defining structure of the divisions of the inferior mediastinum?
the heart and its pericardial sac, as it lies within the middle division (can be seen from a lateral view)
Anterior mediastinum is between what?
the pericardial sac of the heart posteriorly and the posterior aspect of the sternum anteriorly
What does the anterior mediastinum containt?
- only fat, connective tissue and a few vessels in the adult
- before puberty it contained the thymus
Thymus funtion
T-Cell maturation
Posterior mediastinum is between what?
the posterior aspect of the pericardial sac and the anterior aspect of the vertebral column
All 3 portions of the inferior mediastinum are bounded inferiorly by the
diaphragm
Other important structures in the middle mediastinum besides the heart and pericardial sac?
-the ascending aorta(first part from the heart)
-pulmonary trunk (and its division into rt. and lt. pulmonary aa.),
-portions of the superior vena cava,
-pulmonary vv. as they enter the heart
-the termination of the azygos vein,
-the phrenic nn.
-the bifurcation of the trachea into lt. and rt. main
bronchi
What is the pericardium?
also called the pericardial sac, as two layers: outer tough fibrous and inner serous (slippery) layers
What is the fibrous pericardium
tough fibrous layer that restrains the heart during beating from
moving violently around the mediastinum
What does the fibrous pericardium fuse with
- superiorly: fuses with the adventitia (outer CT layers) of the great vessels leaving the heart and entering the superior mediastinum
inferiorly: with the central tendon of the diaphragm
The phrenic nerve is sandwiched between what
the mediastinal pleura and the outer aspect of the fibrous pericardium - along the lateral borders of the pericardial sac
Phrenic n. on both sides of the heart are accompanied by what?
tiny vessels -the pericardiophrenic br. of the internal thoracic a.
How does the fibrous pericardium prevent cardiac tamponade?
due to its unstretchable nature that prevents the accumulation of fluid from inflammation and bleeding from a rupture vessel/chamber letting blood flow into the pericardial sac
What is cardiac tamponade?
when extra fluid builds up in the space around the heart which impedes filling of the heart
What is the serous pericardium?
Separates the fibrous pericardium from the epicardium (surface of the heart)
Serous pericardium is also called what
The serous layer covering the posterior side of the fibrous pericardium is
referred to as the PARIETAL SEROUS PERICARDIUM
What is the visceral pericardium?
That portion reflected out onto the surface of the heart, at the roots of the great vessels
- also called the epicardium
- lies directly on surface of the heart
What is the pericardial cavity?
a potential space between the parietal serous pericardium and the visceral serous pericardium; it is filled with pericardial fluid
Removal of fluid from the sac is referred to as?
pericardial aspiration
What are the two pericardial sinuses?
transverse pericardial sinus and oblique pericardial sinus