TBL 13: Posterior Mediastinum Flashcards
Why can dysphagia and pulmonary hypertension result from mitral valve stenosis?
A mitral valve stenosis results in a backup of blood in the left atrium and subsequent backup of blood in the pulmonary circulation resulting in both left atrial distension and pulmonary tension, respectively.
How do alternate venous pathways to the right atrium differ after obstruction of the SVC superior to the entrance of the azygos vein and after obstruction of the IVC?
If you obstruct the SVC you are then relying on blood getting to the right atrium through the inferior vena cava, so all the blood has to drain through the brachiocephalic vein then subclavian vein then internal thoracic veins then anterior intercostal veins then to posterior intercostal veins then to the azygos vein then to the IVC. Walaa.
Where is the location of the posterior mediastinum?
The posterior mediastinum is between the middle mediastinum and the bodies of vertebrae T5 to T12.
What makes up the majority of the posterior of the heart?
The left atrium
Where is the esophagus compressed and by what structures?
The esophagus is compressed proximally by the arch of the aorta and left main bronchus.
It’s compressed distally at vertebra T10 by the esophageal hiatus of the diaphragm.
How are the esophageal compressions typically observed?
The aortic compression is most evident in a postero-anterior (PA) radiograph after a barium swallow.
The bronchial impression is more evident in lateral views.
Where can the aortic hiatus be found and what structures accompany the aorta as it descends through the hiatus?
The aorta can be see descending through the aortic hiatus along with the thoraic duct and azygos vein at vertebra T12
Where can the thoracic duct be found and what does it do?
The thoracic duct can be found to the right of the descending aorta.
It returns lymph from the lower limbs, pelvis, abdomen, left side of the thorax, left upper limb, and left side of the head and neck to the left venous angle.
Where is the left venous angle located?
The left venous angle is located at the junction formed by the left internal jugular vein and left subclavian vein.
Where is the right lymphatic duct and what does it do?
The right lymphatic duct returns lymph from the upper limb and the right side of the thorax, head, and neck to the right venous angle.
(See image for location)
What is the function of the azygos vein?
The azygos vein drains blood from the walls of the thorax and abdomen and empties into the SVC. It also provies a collateral pathway between the IVC and SVC.
What is the purpose and location of the caval opening?
The caval opening is a hiatus in the central tendon of the diaphragm at vertebra T8 and it enables the IVC to ascend from the abdomen into the thorax.
How is the caval opening formed?
The formation of the caval opening is facilitated by the sinus venosus embedding into the septum transversum?
What are the greater splachnic nerves and where do they arise?
The greater splanchnic nerves are presynaptic sympathetic fibers that orginate in spinal cord segments T5 to T9 and join the anterior rami of spinal nerves T5-T9, then joing the white communicating rami to enter the segmental paravertebral ganglia.
