SUPERIOR MEDIASTINUM Flashcards
Boundaries of superior mediastinum and their location
Anterior - manubrium
Inferior - Line from sternal angle to T4/T5 disc
Posterior - T1-T4 vertebrae
Superior - Thoracic inlet
Contents of superior mediastinum
- Thymus
- Brachiocephalic veins, SVC
- Aorta - Brachiocephalic a., L common carotid a., L subclavian a.
- Vagus and Phrenic nerves
- Trachea
- Esophagus
Location of thymus
beneath sternum - in superior and anterior mediastinum
Thymus in children
functional
Thymus in adults
involution
Brachiocephalic veins are formed by the union of
internal jugular and subclavian veins
L and R brachiocephalic veins join to from the
SVC
L brachiocephalic vein course and location
long horizontal course (SVC is R shifted) - posterior to manubrium
L brachiocephalic vein tributaries
IJV, subclavian, internal thoracic vein, thoracic duct
R brachiocephalic vein course and location
short vertical course – lateral to brachiocephalic artery
R brachiocephalic vein tributaries
IJV, subclavian, Internal thoracic vein, R lymphatic duct
What tributaries differ between R and L brachiocephalic veins?
L = thoracic duct, R = R lymphatic duct
same = IJV, subclavian, Internal thoracic vein
SVC is formed by the union of
R and L brachiocephalic veins
SVC ends at
R atrium
What structures are anterior to SVC?
portion of R lung + associated pleura
What structures are posterior to SVC?
R Vagus nerve, R pulmonary artery, R main bronchus, azygos vein
What structures are medial to SVC?
Ascending aorta
What structures are lateral to SVC?
R phrenic nerve
What is the major clinical correlate of the SVC?
SVC Syndrome
SVC Syndrome
Any disease process that results in compression of SVC = Obstruction
- Increased pressure in venous system draining into SVC
- Fluid leaks out of venous system into interstitial tissues = Swelling or Edema
- Affects upper limbs, head and neck (including brain)
SVC most commonly occurs due to what? What else could cause this?
lung cancer in RUL
others: enlarged lymph nodes (lymphoma) or aortic aneurysm (swelling of heart)
What veins drain into the SVC?
veins from arm/head/neck
4 parts of the aorta
Ascending, Arch, Descending Thoracic, and Abdominal
What type of vessel is the aorta?
strong, high-pressure vessel