L7: Posterior mediastinum Flashcards
boundaries of posterior mediastinum
posterior border: vertebral column
Anterior boundary: pericardium
Lateral: lungs
3 openings in the diaphragm
1.caval opening: IVC goes through(~ T8)
2.Oesophageal hiatus(~T10)
3. Aortic hiatus(~T12)
purpose of the azygous system of veins
drain the thorax( esp posterior)
what veins connect up to form the azygous vein?
starts off as right ascending lumbar vein and connects up with right subcostal vein
drainage into azygous vein
on the right side:
some superiorly: right superior intercostal vein
intercostal veins
right subcostal and right ascending lumbar veins.
on the left side:
Hemiazygous vein
accessory hemiazygous vein
at what lvl do the hemiazygous and accessory hemiazygous cross over to the right to connect with the azygous vein?
T8-T9
what are the veins on the left side of the thorax?
-left superior intercostal vein
-Accessory hemiazygous vein
-Hemiazygous vein ( from ascending lumbar vein)
+intercostal veins
+posterior intercostal vein
where do ascending lumbar veins come from?
ileac veins
Why is azygous system quite useful?
ascending lumbar veins come from ileac veins
Can be an alternative route for blood from lower body to drain into the heart
if there is a problem with the vena cavas( particularly the IVC)
e.g. in people with tumours in IVC can see enlarged azygous system
swhat is one of the main source of lymphatic drainage of lower limbs and abdomen?
cisterna chyli
Pathway of cisterna chyli to thoracic duct
passes through aortic hiatus with the aorta and runs up more towards the right side of the vertebral column. At transthoracic plane shifts over to the left. Wants to get to the venous system to drain into. Lower pressure in the venous system higher.
Comes in behind the oesophagus and to the junction of Int. Jug. Vein and L. Subclavian vein.- thoracic duct.
what areas of the body does the thoracic duct drain?
large area
problem can be anywhere and travel to the thoracic duct
what are the compressions on the oesophagus?
arch of the aorta: pulsatile compression
left primary bronchus passes in front of the oesophagus and pushes on it
At the oesophageal hiatus
(can be good as stops gastric contents coming back up into oesophagus)
oesophagus is behind the left atrium- can compress as well if there is distension of the left atrium.
what pathological conditions can lead to dysphagia
narrowings can make it hard to swallow( especially with conditions that exaggerate the narrowings: aortic aneurism, tumours in the bronchi, overly swollen lymph nodes or scarring from gastric reflux)> dysphagia
what is the arterial supply and venous drainage of the oesophagus?
+ nerve supply
what arteries come off the thoracic aorta
posterior intercostal arteries
anastomose with anterior intercostal arteries
what is coarctation of the aorta
Coarctation of the aorta is a congenital heart defect characterized by a narrowing or constriction of the aorta, the main artery that carries oxygenated blood from the heart to the rest of the body. This narrowing typically occurs in the region where the aorta arches and descends (near the ductus arteriosus), just distal to the origin of the left subclavian artery.
Key features and effects of coarctation of the aorta include:
Obstruction of Blood Flow: The narrowing of the aorta in coarctation restricts the flow of blood from the heart to the lower part of the body. This obstruction leads to increased pressure and workload on the left ventricle, the chamber responsible for pumping blood into the aorta.
Hypertension: As a result of the narrowed aorta, blood pressure is increased in the upper body and arms (proximal to the coarctation) but reduced in the lower body and legs (distal to the coarctation). This can lead to hypertension (high blood pressure) in the upper body and decreased blood flow to the lower extremities.
Collateral Circulation: To compensate for the reduced blood flow through the narrowed aorta, collateral blood vessels may develop to bypass the constriction. These collateral vessels often connect with branches of the intercostal, internal mammary, and subclavian arteries, forming a network of additional blood vessels around the coarctation site.
Cardiac Strain and Complications: The increased workload on the left ventricle due to the narrowed aorta can lead to left ventricular hypertrophy (thickening of the heart muscle). Over time, this can result in heart failure or the development of other cardiac complications, such as aortic valve abnormalities, aortic aneurysm, or aortic dissection.
Signs and symptoms of coarctation of the aorta may vary depending on the severity of the narrowing. They can include:
High blood pressure in the upper body and arms but low blood pressure in the lower body and legs
Weak or absent pulses in the lower extremities
Cold lower extremities
Leg cramps or pain with exercise
Heart murmur
Shortness of breath
Headaches or dizziness
Treatment for coarctation of the aorta typically involves surgical repair or catheter-based interventions. Surgery may involve removing the narrowed portion and reconnecting the healthy segments of the aorta. Balloon angioplasty and stenting are minimally invasive techniques that can be used to widen the narrowed segment of the aorta using a catheter-based approach.
Early diagnosis and timely intervention are important to prevent complications and ensure optimal outcomes for individuals with coarctation of the aorta. Regular follow-up and lifelong monitoring are often recommended to detect and manage any potential long-term issues.
what are the ways of bypassing coarctation (past L. subclavian a)
1.blood can go through brachiocephalic artery or L. subclavian artery> into RITA and LITA> into anterior thoracic and then posterior thoracic arteries (through anastomoses)> into the thoracic aorta
- through the anastomoses of the superior and inferior epigastric arteries. down to the external ileac arteries.
These alternative vessels enlarge
