Mediastina Flashcards
boundaries of anterior mediastinum
anterior - transversus thoracis m., sternum, costal cartilages
posterior - fibrous pericardium
lateral - parietal pleura
contents of anterior mediastinum
sternopericardial ligaments thymus (pre-puberty) internal thoracic vessels fat, lymph nodes nerves
n. of cardiac plexus mostly arise from…
vagus (CN X)
sympathetic trunk
layers of mediastina
- veins
- great arterial vessels, ligament arteriosum
- trachea, vagus n. esophagus, thoracic aorta
- thoracic duct and azygos venous system
- mediastinal autonomic n.
retroesophageal R subclavian
no brachiocephalic trunk. RSA coming right off aorta and traveling behind esophagus
40% of Down syndrome pt
ligamentum arteriosum
vestige of fetal life ductus arteriosus, scars down bc of high oxygen content
from pulmonary trunk to arch of aorta
shunts venous blood into the aorta
point of weakness in trauma
ductus arteriosus
blood that gets into fetal RV and through pulmonary trunk takes shunt (ductus arteriosus)
blood is partly venous but also has maternal oxygenated blood
fetal blood flow
umbilical vein from placenta –> liver –> RA –> deflected toward foramen ovale by valve of IVC –> LV then out
ligamentum venosum
scarring down of umbilical vein after birth
if aspirate something, would it go to R or L bronchus?
R bronchi - more vertically oriented and larger
primary target of vagus n.
abd and below, but also innervates larynx
esophagus
long tube from C6 (cricopharynxgeus m.) to T10)
landmark for IVC
T8
landmark for esophageal hiatus
T10
landmark for thoracic aorta becoming abdominal
T12
main trunks of of nerves covering esophagus
mainly from vagus m.
also some sympathetic fibers
L vagus n. travels _____ to esophagus
R vagus n. travels _____ to esophagus
L vagus –> anterior to esophagus
R vagus –> posterior to esophagus
“LARP”
Gives more clear views of heart and valves, particularly useful it pt is obese
trans-esophageal echocardiography
hiatal hernia
weakening of R crus of diaphragm, pt of stomach goes into thorax
comm in elderly
thoracic (descending) aorta
T4/T5 to T12
firmly tethered by posterior intercostals
other unpaired branches
- esophageal a.
- bronchial a.
- pericardial a. (to dorsal pericardium)
aortic hiatus
T12
cisterna chyli
dilation at L1-L3 where thoracic duct begins
thoracic duct runs anterior to
anterior longitudinal ligament
thoracic duct traverses from R to L at which spinal level
~T4
thoracic duct empties into
L. venous angle (junction of L. internal jugular v. and L. subclavian v.)
RUQ drains into ______, while the rest drains into _____
RUQ –> right lymphatic duct
Everything else –> thoracic duct
(EXCEPT lower left lobe of lung, left atrium, left ventricle)
Thoracic duct drains all but upper quadrant with the exception of…
lower left lobe of lung, left atrium, left ventricle
lymphatic drainage of heart
right side –> left (thoracic duct)
left side –> right (R lymphatic duct)
mediastinal lymph nodes
Virchow's node (sentinal node) posterior mediastinal nodes paratracheal nodes superior/inferior tracheobronchial nodes superior phrenic nodes
Enlarged Virchow’s node can be first sign of…
gastric cancer
system of veins draining thoracic and abd wall
azygos veins
azygous v. forms from
ascending lumbar veins uniting with posterior intercostal veins
hemiazygous v.
tributaries training into azygous v. –> highly variable
hemiazygous v. –> just above diaphragm
then a break
then accessory homozygous would be above
Azygous vein functions
drains post. thoracic and abd walls
provides direct connection between IVC and SVC
provides imp venous shunts in SVC/IVC pathology
Azygos v. has valves, T or F?
False No valves (like most non-extremity veins)
IVC filters can function to
collect blood clots from legs so they don’t travel up to lungs
SVC blocked… different routes for venous blood to RA?
- back up and travel thru azygous arch. down azygous v., join IVC and go up to heart.
- travel thru internal thoracic v. (on either side of sternum), connect to anterior intercostal v., which go around and become posterior intercostal v., join azygous v., go down and join heart via IVC
mediastina autonomic n.
parasympathetic
sympathetic
- cardiopulmonary splanchnic
- thoracic splanchnic
cardipulmonary splanchnic n.
sympathetic originating from T1-T4
1st neurons…
can either synapse at thoracic ganglia and post-synaptic fibers can travel to heart/trachea/esophagus…
OR
can travel upwards to synapse at cervical ganglia, then travel back down as superior/middle/inferior cardiac n. to innervate heart (trachea/esophagus.. to lesser extent)
thoracic splanchnic n.
originate at T5-T12
pass through paravertebral ganglia (in abd), then post-ganglionic gibers follow blood vessels to abd targets
unite to form 3 distinct n. (greater, lesser, and least splanchnic n.)
all splanchnic n. fibers in thorax are preganglionic
greater splanchnic n.
T5-T9
lesser splanchnic n.
T10-T11
least splanchnic n.
T12
thoracic splanchnic n. have functions in thorax
T or F
F, only arise from thorax region bc that’s where sympathetic fibers arise
all function is BELOW diaphragm
periarterial sympathetic plexus
post-ganglionic sympathetics fibers follows this to their targets
ganglia of abd
celiac ganglia
aorticorenal ganglion
superior mesenteric ganglion and plexus
inferior mesenteric ganglion
great arterial vessels
- brachiocephalic trunk
- divides to form R subclavian and R common carotid - L common carotid
- L subclavian
brachiocephalic trunk may branch into
thyroid ima artery
Why might dysphagia be an early sign of mediastinal pathology (aneurism, enlarged nodes, cancer, etc.)
bc esophagus passes thru mediastinum and expands during swallowing
why might progressively worsening voice problems (hoarseness) or dyspnea (from brachial compression) be indicative of mediastinal pathology?
recurrent laryngeal n. (via vagus n.) may become damaged due to aortic aneurisms, enlarged lymph nodes, tumors
circipharyngeus
upper esophageal sphincter
