Lecture 10 Flashcards
Describe the azygos system?
It is a system of veins. Runs up both sides of the vertical column at the back (posterior). The azygos vein starts where the right subcostal vein meets the right ascending lumbar vein. It travels up the right hand side, and arches up and over and drains into the SVC. Paired with it on the other side is the hemiazygos vein (descending lumbar vein and left subcostal vein) and coming down from the upper region is the accessory hemiazygos vein - the hemiazygos and the accessory hemiazygos come across and meet the azygos vein at around T8-T9.
Describe Porto-Systemic Shunting:
Portal hypertension occurs when there is an increase in pressure in the portal vein (normally when the liver is congested). This will cause blood to back flow so that it can reach the heart somehow. In a normal system the IVC goes form the liver to the heart, the stomach is drained by the portal vein, the oesophagus is drained by the left gastric vein and the upper oesophagus is drained by the azygos system which drains into the SVC. The veins to the viscera do not have valves in them so the blood can flow in either direction (back flow). The veins in the oesophagus will be filled with blood (varices - oesophageal).
Describe the thoracic duct?
Runs up the midline of the vertebral column and is flat and hard to find. It drains all of the lymphatic fluid from everywhere except the right arm and some of the face. It starts in the abdomen at the cisterna chyli, it travels up in the posterior part of the thorax in the midline and then crosses over to the left hand side at around T5. It pops up in the left supra-clavicular region where it drains back into the venous system. It drains where the left internal jugular vein meets the left subclavian vein. There is a valve where the thoracic duct meets these two veins to stop venous blood from going down the thoracic duct. It drains into here, so finding lymph nodes (swollen) is an indicator of all sorts of diseases.
Describe the Oesophagus?
Will find this in the posterior mediastinum. It is a muscular tube. It is compressible and soft.
Describe the three regions where the oesophagus gets compressed?
- Arch of the aorta crosses up in posterior and to the left. Could be worried that the person was having an aortic aneurysm if the oesophagus is extensively compressed. If starts bleeding it is a fast sudden death
- Where the oesophagus runs posterior to the left main bronchus. Not particularly useful areas of compression. Could be a lung cancer.
- Where the oesophagus passes through the hiatus in the diaphragm - acts as a sphincter (LOS).
Anyone having difficulty swallowing will undergo a barium swallow. Need to think about the oesophagus and what is around the oesophagus.
Describe the arterial supply to the oesophagus?
Gets some supply directly from the aorta, particularly at the superior end (it has supply from the bronchial arteries off the aorta). At the inferior end it gets branches form the left gastric artery.
Describe the venous supply to the oesophagus?
Azygos system (into all three veins) for the superior part.. The lower part is to the left gastric vein.
Describe the nerve supply to the oesophagus?
Parasympathetic supply from the vagus and sympathetic supply from the trunks.
Describe the Thoracic Aorta?
The thoracic aorta is the descending aorta. It becomes the thoracic aorta after the aortic arch gives off the brachiocephalic branch, the left common carotid and the left subclavian artery. After giving off the bronchial arteries and the posterior intercostal arteries and piercing through the thorax it becomes the abdominal aorta.
Describe a 6 week check?
You will check the radial and the femoral pulse. You check radial-radial and radial-femoral delay. This is when you take the pulse of both arms to check if they are the same, and the radial and femoral pulse.
How does a radial-radial or radial-femoral delay occur?
Coarctation of the aorta. Narrowing of the aorta, somewhere in the region where the ductus arteriosus has closed off. It can happen anywhere around the arch of the aorta. If it occurs before the ductus then it is incompatible with life. If it occurs after the ductus then there is still some blood flow through the aorta. Important to look for.
How do you treat a coarctation?
There were no surgical options for coarctation. You either die as a neonate or you survive past that. Your body has a way to get around the coarctation (bypass it):
- Increase the blood flow down the internal thoracic arteries into the anterior intercostal arteries. The anterior intercostals then meet with the posterior intercostal arteries and then can continue down the rest of the aorta 9it has bypassed the blockage to the thoracic artery. In an patient with this, you will see on an X-ray notching on their ribs - this is the place where the anterior intercostal arteries have become so big 9due to the extra blood flow).
- Increase the blog flow down the internal thoracic arteries, and it continues all the way down the anterior intercostals and into the superior epigastric artery. The superior epigastric meets with the inferior epigastric artery. The inferior epigastric is a branch off the external iliac, which will then go into the femoral artery. Thus blood flow to the legs.
