ICL 1.13: Mediastinum Flashcards
what is the mediastinum?
the anatomic region located between the lungs described as a partition separating the two pleural cavities
it serves as a corridor through which structures from the head and neck region connect with lower regions of the body and vice versa
it contains all the principal tissues and organs of the chest EXCEPT the lungs
where is the manubriosternal joint?
the second rib!! it’s in-between T4 and T5
the sternal angle is at the 2nd rib!! aka Angle of Louis where the manubrium meets the body of the sternum
what are the boundaries of the mediastinum?
it extends from the sternum back to the vertebral column
it’s bound laterally by the pericardium and the mediastinal pleurae
which structures are in the mediastinum?
- heart
- thymus
- portions of the esophagus and trachea
what are the divisions of the mediastinum?
the mediastinum is split into a superior and inferior division at the sternal angle
the inferior division is split into the anterior, middle and posterior
slide 8 and 10
where is the superior mediastinal compartment located?
it is located above the manubriosternal angle
its posterior boundary is made up of the first four thoracic vertebrae
above, the superior mediastinum is continuous with the neck
below it is continuous with both anterior and posterior mediastina
laterally it is limited by parietal (mediastinal) pleura
what are the contents of the superior mediastinum?
- thymus
- aortic arch
- superior vena cava
- trachea
- esophagus
- right and left vagus nerve
- phrenic nerves
- thoracic duct
all of these pass through the superior mediastinum!! some of these go through multiple parts of the mediastinum
where is the anterior mediastinal compartment located?
anterior mediastinal compartment is bordered by
- the sternum anteriorly
- the pericardial sac posteriorly
so basically it’s the part of the inferior mediastinum in front of the heart
what are the contents of the anterior mediastinum?
- sternopericardial ligament (it’s actually just fat)
- fat
- lymph nodes
where is the middle mediastinal compartment located?
the borders are:
ventrally: the anterior mediastinal compartment
dorsally: the posterior mediastinum
what are the contents of the middle mediastinum?
- the pericardium
- heart
- phrenic nerves
- pericardiacophrenic vessels
- stems of great vessels
where is the posterior mediastinal compartment located?
the borders are:
anteriorly: pericardial sac
posteriorly: the anterior surface of the vertebral bodies
what are the contents of the posterior mediastinum?
- descending aorta
- azygous system of veins
- vagus nerve
- thoracic duct
- lymph nodes
- thoracic splanchnic nerves
- esophagus
where is the thymus located?
it’s a lymphoid organ located in the lower part of the neck and the anterior part of the superior mediastinum
it lies posterior to the manubrium and extends into the anterior mediastinum
it grows till you’re 5-6 years old then turns into fat after puberty!
what are the terminal branches of the internal thoracic artery?
it ends at the sixth costal cartilage by dividing into musculophrenic and superior epigastric arteries