Posterior mediastinum and diaphragm Flashcards
What is the posterior mediastinum
the area behind the fibrous pericardium
What structures are in the posterior mediastinum
descending thoracic arch, oesophagus, right and left ganglion sympathetic chain which has important nerves running off it, lymph nodes, running upwards is the thoracic ducts, vena azygous (right), hemizygous and accessory hemiazygos vein (left).
What are the boundaries of the inferior mediatsinum
Superior - sternal angle
Inferior - diaphragm
Anterior - heart and pericardium
Posterior - T5-T12 vertebral bodies
Where is the anterior mediastinum
T5-T9
Where is the middle mediastinum
T5-T8
Where is the posterior mediastinum
T5-T12
What structures come of the sympathetic trunks (T5-T12 ganglia)
greater splachnic nerve, lesser splanchnic nerve, least splanchnic nerve – run anteriorly down the bodies of the vertebrae, hit the pre-aortic ganglia and plexuses.
What are the contents of the posterior mediatsinum
Descending thoracic aorta, azygous veins, thoracic duct, Eosophagus, sympathetic trunk (DATES)
Where is the thoracic duct located
ascending from cisterna kylie, moves superiorly through posterior mediastinum, crosses from right to left lateral at the superior margin of the posterior mediastinum, around the thoracic plane into the left venous angle
How does the lymphatic system maintain homeostasis
by returning most of the fluid that has been diverted back into your blood
What are the 4 main parts of the lymphatic system
lymph, lymph vessels, lymph nodes, lymph organs
What is lymph
water solution (does not contain red blood cells), remains in closed circulatory loop because they are too large to be passed through capillary membranes
What do lymphatic vessels help with
help reabsorb the fluid
What is the function of lymph nodes
checkpoints that monitor and cleanse the lymph as it filters through.
Examples of lymphoid organs
spleen, thymus adenoids, tonsils
What are the thymus and spleen the site of
site for maturing lymphocytes
What does most lymph start off as
blood plasma which gets forced out of your capillaries
What are the capillary beds
where capillaries carry blood from your arterioles and arteries and feed blood into venules then veins
What are capillary beds the site of
transfer of waste and nutrients as blood pressure force plasma out of arteriole end of capillaries and into the interstitial fluid between the cells of the tissue
What pressure causes some of the fluid that has been lost to be absorbed at the venous end
osmotic pressure
What are lymphatic capillaries made from
loosely overlapping endothelial cells that form little flap like valves that can only open in one direction
What do the flap like valves in lymphatic vessels do
ensure lymph fluid will not leak back into the interstitial space
What happens to the valves when pressure in interstitial fluid becomes greater than the pressure inside the lymphatic capillary
the flaps push open and take in fluid to remove the pressure
What happens to the fluid that has been taken in by the lymphatic vessels
flows through successively larger lymphatic vessels to collecting vessels and then to larger trunks. Then into 1 of 2 large lymph ducts that feed back into the lowest pressure area of the circulatory system
What does the right lymphatic duct drain
all the lymph collected from the right upper area of the torso, right arm , head and thorax into the internal jugular vein
Where does the larger thoracic duct take the lymph
takes lymph from the rest of the body and dumps it into the subclavian vein
What kind of muscle do lymphatic vessels have
skeletal muscle
What helps lymph move along
pressure changes in the thorax during breathing and pulsations of adjacent arteries
What muscle in the lymphatic vessel walls help lymph to move
smooth muscle
What does recovering 3L of blood a day prevent
prevents drop in blood pressure and little/no oxygen delivery or waste pick up
What does a blockage in lymphatic system result in
oedema or swelling that can constrain blood flow and lead to serious complications
How does the lymphatic system have a role in the immune system
intestinal fluid that drains into lymph vessels contain bacteria that if not killed in the lymph system can enter your heart
Which immune cells are housed in the lymphatic system
T cells, B cells, macrophages and reticular cells
What regularly inspect lymph nodes
lymphocytes
What can lymphocytes trigger the release of
macrophages and can activate the general immune system
Where are lymphocytes found
the loose reticular connective tissue that makes up a large part of the nodes and most of your other lymphoid organs
What are swollen lymph nodes a sign of
disease or infection
Where is mucosa associated lymphoid tissue found
mucosa membrane around the body, outside of the lymphatic vessels (found in intestine etc..)
What are Peyer’s pathes
lymph tissue in small intestine which is a check point in GI tract.
What do the azygous veins join
the superior vena cava
Where do the azygous veins run
begins below the diaphragm and runs up along the right side of the vertebral column then arches over the right main bronchus
Where do azygous veins receive blood from
the posterior and lateral parts of the chest wall
On the right side what runs into the azygous veins
posterior intercostal veins
Where do the posterior intercostal veins run into on the right side
the 2 hemi azygous veins which then empty into the azygous
Describe the arrangement of the fibres of the diaphragm
fibres that converge from all around the circumference to insert on the central tendon of the diaphragm
Where does the diaphragm arise from
arises from a line that goes right around the inside of the lower thoracic aperture that has one interruption
Where is the line of the attachment of the diaphragm
goes from the back of the sternum (lower), along the inside of the costal arch and around to the tip of the 12th rib
When does the diaphragm arises on each side of the fascia which overlies quadratus lumborum and psoas major muscles
between the 12th rib and the body of the second lumbar vertebra
What 3 structures pass through the diaphragm
esophagus, inferior vena cava and descending aorta
Where is the caval hiatus
T8
What passes through the caval hiatus
inferior vena cava and terminal branches of the right phrenic nerve
Where is the oesophageal hiatus
T10
What passes through the oesophageal hiatus
oesopahgus, right and left vagus nerve, oesaphageal branches of left gastric artery/vein
Where is the aortic haitus
T12
What passes through the aortic hiatus
aorta, thoracic duct and azygous vein
What is present on each of the openings of the diaphragm
a thickening called the crus (crura - plural)
Where does the left crus arise
from the body of L2
Where does the right crus arise
from the body of L3
What do the 2 crura do
arch over the aortic opening forming the median arcuate ligament
What surround the oesophageal hiatus
fibres of the 2 crura which cross over
What happens to the diaphragm when it contracts
the whole sheet of muscle, together with the central tendon, moves downward, expanding the lungs and causing us to breathe in
What happens to other structures when the diaphragm contracts
the structures below it (the contents of the upper part of the abdominal cavity) are pushed downward causing bulging of the abdominal wall
How is inspiration produced at rest
by the downward pull of the diaphragm, with little or no movement of the ribs
What is the return movement of the diaphragm produced in quiet expiration
movement is produced passively by elastic forces (elastic contraction of the lungs them selves
