Thorax 4 Flashcards
what does the mediastinum contain
all thoracic structures apart from lungs and surrounding pleura
how is the superior mediastinum and inferior mediastinum separated?
there is a horizontal plan at level between T4 and T5 and the sternal angle of sternum (also at birufication of trachea)
what is in the superior mediastinum?
-thymus (also in anterior mediastinum)
-SVC and 2 great veins
-arch of aorta
-trachea
-oesophgus
-thoracic duct -> lymphatic trunks-> subclavian veins
why is one brachiocephalic vein longer than the other
left is longer than right due to left-> right venous shunting where the superior vena cava sits slightly to the right
how is the superior mediastinum bound?
superiorly: superior thoracic aperture
inferiorly: sternal angle-> transverse thoracic plane
anteriorly: bound by manubrium
posteriorly: bound by first 4 vertebrae
what are the nerves innervating the heart
-right and leftvagus nerve-> vagal cardiac branches
-cardiac nerves from sympathetic trunk-> superficial cardiac plexus (sort of under aortic arch)
what is in the most anterior part of posterior mediastinum
-descending thoracic aorta
-oesophagus
most posterior structures of the inferior mediastinum
-azygos system of veins
-thoracic duct
-sympathetic trunks on either side of vertebral column
when does the descending thoracic aorta start?
continuation of arch of aorta (which is in the superior mediastinum) and starts at T5
what does the thoracic aorta do?
-gives off mediastinal branches (and more) which supplies things such as the lymph nodes of posterior mediastinum
-supplies the posterior intercostal arteries
what are the branches of the vagus nerve on the oesophagus called?
oesophageal plexus- innervates oesophagus
what do the mediastinal branches of aorta supply?
lymph nodes
what do the pericardial branches of the thoracic aorta supply?
posterial aspect of pericardium of heart
oesophageal branch of thoracic aorta supplies the?
oesophagus
what does the oesophageal plexus of vagus nerve converge into?
the anterior vagal trunk (left vagus nerve) and posterior vagual trunk (right) (on anterior and posterior surfaces of oesophagus)
what side of the oesophagus is the thoracic aorta on
left side
when do the superior phrenic arteries branch off?
right before thoracic aorta passes through aortic hiatus
what does the superior phrenic arteries supply?
the superior aspect of the diaphragm
where does the azygous vein sit?
right hand side on thoracic verterbral bodies
other than the left brachiocephalic vein, what other vein shows left-> right venous shunting?
hemiazygous vein
how is the azygous vein formed?
uniting the right ascending lumbar vein and right subcostal vein quite low down
azygous vein function
drains majority of posterior intercostal veins (T1-T2 first intercostal space drained by supreme intercostal vein)
hemiazygos vein role
responsible for draining intercostal spaces from 9th intercostal space-> last intercostal region 11
(accessory hemiazygos does 4-8-> left side be dif ig cah right side azygous 2-11 w/ siv for 1)
what is the only intercostal space that isnt drained by azygos veins and what does it drain into
T1-T2 first intercostal space drained by supreme intercostal vein into left
and right brachiocephalic vein
at what level does the azygous vein unite with superior vena cava
at level of sternal angle (between t4 and t5)
what is the accessory hemiozygos vein?
branch above the hemiozygous vein of the azygos vein that drains the left posterior intercostal veins 4-8
drainage of the cisterna chyli
penultimate drainage point for all of the lymmph below the diaphragm before it is drained by the thoracic duct
thoracic duct role
-largest lymphatic duct responsible for draining all lymphatic fluid from entire body except for upper right quadrant into junction between
left internal juglar vein and left subclavian vein
splanchic nerves branching
-greater
-lesser
-least
where do the splanchic nerves travel?
-travels down through diaphragm to supply the viscera of the abdomen with sympathetic innervation
thoracic duct travel
goes over the vertebral bodies then moves off left to drain in junction of left interal juglar vein and left subclavian vein (thoracic duct)
describe how the sympathetic trunk travels and what they do
sympathetic efference from T1 to L2 will
-travel up chain into cervical ganglia providing sympathetic innervation
-or go down all the way to sacrum and coccygeal regions to supply pelvis and lower limbs with sympathetic innervation
what nerves innervate heart with sympathetic innervation
levels T1-T4 cardiac branches of sympathetic chain
