Superior Mediastinum and Posterior Mediastinum Flashcards
What are the boundaries for the superior mediastinum?
-Anterior: Manubrium
-Inferior: Line from the sternal angle to T4/T5 disc
-Posterior: T1-T4 vertebrae
-Superior: Thoracic inlet
What are the contents of the superior mediastinum?
-Thymus
-Brachiocephalic veins (L/R), Superior Vena Cava
-Aorta (Btachiochephalic artery, left common carotid artery, left subclavian artery)
-Vagus and prenic nerves
What is the location of the thymus?
Beneath sternum, in superior and anterior mediastinum
What is the function of the thymus?
Children: Functional T cell immunity
Adults: Involution, replaced by fat
What forms the Brachiocephalic Veins?
-union of internal jugular and subclavian veins
-Left and right brachiocephalic veins converse together to make the superior vena cava
Left Brachiocephalic vein
Long horizontal course, posterior to the manubrium
Tributary veins of the left brachiocephalic vein
Left internal jugular, left subclavian, internal thoracic, thoracic duct
Right brachiocephalic vein
Short, vertical course, lateral to brachiocephalic artery
Tributary veins of the right brachiocephalic vein
Right internal jugular, right internal thoracic, right lymphatic duct
What is the relationships of the Superior Vena Cava?
-Anterior: of the right lung and associated pleural
-Posterior: right vagus nerve, right pulmonary artery, right main bronchus, azygous vein
-Medial: ascending aorta
-Lateral: Right phrenic nerve
Azygous Vein
Collects the posterior VAN and empties in the posterior part of the Superior Vena Cava
Superior Vena Cava Syndrome
Any disease the process that results in compression of the superior vena cava
What happens in Superior Vena Cava Syndrome?
Increase in pressure in venous system draining into the SVC.
Fluid leaks out (hydrostatic) of venous system into interstitial tissues=swelling and edema
What parts of the body does Superior Vena Cava syndrome affect?
Upper limbs, head, neck (including brain)
What causes Superior Vena Cava Syndrome?
Lung cancer, enlarges lymph nodes, aortic aneurism
What are the parts of the aorta?
Ascending, arch, descending thoracic, abdominal
Where does the the ASCENDING part of the aorta begin, end, branches off of and the relationship?
Begin: at eh aortic valve (3rd left costal cartilage)
Ends: at the 2nd right costal cartilage
-Branches: off the ascending aorta, left and right coronary artery
-Relationship: lateral to SVC
Where does the ARCH of the aorta begin, end, branches off of and the relationship?
Begins/ends: T4/T5 vertebral disc, arches posteriorly over pulmonary trunk and left main bronchus
Branches: off the arch, brachiocephalic artery, left common carotid artery left
Relationships:
-Anterior: left recurrent laryngeal nerve wraps under the aortic arch and back to innervate the voice box, left vagus nerve, left phrenic nerve
-Posterior: Trachea/bifurcation, esophagus
What does the descending thoracic branch off of?
Posterior VAN arteries
What is an aortic aneurysm?
dilation of the aorta. Often asymptomatic but if large enough may produce symptoms by affecting nearby structures
Aortic Aneurysm: ascending
Compress SVS
Aortic Aneurysm Arch
(A) Stretching of the left recurrent laryngeal nerve=horse voice
(B) Compress trachea/left bronchus = cough, wheezing
(C) Compress esophagus=dysphagia
What are the Aortic Arch Branches?
-Brachiocephalic artery
-Left common carotid artery
-Left subclavian artery
What does the Brachiocephalic artery become?
Right common carotid and right subclavian artery @ sternoclavicular joint; may give rise to accessory Thyroid ima artery
What is the relationship of the Brachiocephalic artery?
Anterior: Brachiocephalic vein
Posterior: Trachea
What is the relationship of the Left Common Carotid Artery?
-Anterior: brachiocephalic vein
-Posterior: trachea and left recurrent laryngeal nerve
-Lateral: vagus nerve, left phrenic nerve
What is the relationship of the left subclavian artery?
Runs lateral to trachea and left common carotid and exits the mediastinum at the sternoclavicular joint
What is the function of the Vagus Nerve?
In mediastinum innervates cardiac, pulmonary, esophageal plexus.
