Exam 3: Mediastinum Part 1
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Exam 3: Mediastinum Part 1
review of 7/12 lecture on Mediastinum for exam 3
What is the mediastinum?
3-D space between pleural cavities that extends vertically from thoracic inlet and to thoracic outlet
What are the divisions of the mediastinum?
What separates the superior mediastinum from the inferior mediastinum?
imaginary plane that passes through sternal angle and interverterbral disc between T4-5 vertebrae
Which vessel is just below the superior mediastinum?
pulmonary trunk and arteries
Where is the inferior mediastinum?
lies below the imaginary plane separating the two divisions
What are the subdivisions of the inferior mediastinum?
What makes up the middle (central) component of the inferior mediastinum?
heart and pericardium
What is contained in the superior mediastinum?
all structures entering and exiting thoracic inlet
great vessels of heart
3 branches of aortic arch
left recurrent laryngeal nerve
Where is the thymus gland found?
Where is the anterior mediastinum?
located posterior to sternum, just in front of pericardium
What is found in the anterior mediastinum?
Which mediastinum are the heart and pericardial sac found?
Where is the middle mediastinum located?
between anterior and posterior mediastinum
Where is the posterior mediastinum located?
between middle mediastinum (pericardium) and anterior longitudinal ligament
stretches from T5-12
What does the anterior longitudinal ligament cover?
anterior surface of vertebral column
What is contained in the posterior mediastinum?
structures oriented either vertically or horizontally
What vertically oriented structures are found in the posterior mediastinum?
descending thoracic aorta
azygos system of veins
greater splanchnic nerve
What horizontally oriented structures are found in the posterior mediastinum?
intercostal arteries, veins, and nerves
What is the esophagus? What does it connect?
muscular tube connecting pharynx w/ stomach
Where does the esophagus begin?
level of larynx/C6 vertebra
What does the esophagus descend through?
What does the esophagus lie next to?
After the esophagus descends through the thorax what does it enter?
What does the esophagus pass through before it enters the abdominal cavity?
esophageal hiatus in respiratory diaphragm
Is the esophagus normally collapsed or held open?
Approximately how wide is the esophagus?
About how long is the esophagus?
The esophagus extends vertically from which vertebrae levels?
Where are the locations of the constrictions of the esophagus?
at commencement (origin)
where passes posterior to aortic arch
where passes posterior to left main bronchus
where passes through esophageal hiatus
Why are the constrictions of the esophagus important?
constrictions can adhese and block the pathway for food
doctors must know location when doing a scope
Is the esophagus anterior or posterior to the anterior longitudinal ligament?
While in the neck and superior mediatinum, the esophagus is anteiror or posterior to the trachea?
While in inferior mediastinum, the esophagus is anterior or posterior to left atrim?
What innervates the esophagus?
vagal nerves from nerve network
The vagal nerves come from which nerve network?
Where is the esophageal plexus?
on external surface of esophagus
Do the vagal nerves provide sensory or motor fibers to the esophagus?
Where does the arterial supply of the esophagus begin?
in cervical region
Where does the arterial supply of the esophagus extend?
to abdominal region
What provides arterial supply to the esophagus?
inferior thyroid arteries
aortic esophageal arteries (2 or 3)
left gastric artery
inferior phrenic arteries
What do the esophageal veins correspond to?
the arteries which supply it
Many of the esophageal veins are tributaries to what?
azygos system of veins
Why is venous drainage of esophagus clinically important?
possibility of esophageal varices, observed in patients w/ cirrhosis of the liver
The left gastric vein provides dirct connection between what?
esophageal venous plexus and hepatic portal system
Where does the hepatic portal system receive venous blood from?
What can the venous blood from the gastrointestinal tract bypass and return to the right atrium?
How does venous blood bypass a cirrhotic liver and return to the right atrium?
via esophageal venous plexus
What happens if esophageal venous plexus becomes engorged with blood?
causes many vessels to dilate and become subject to rupture
esophageal varicise (varicose veins in esophagus)
Where does the esophageal lymphatic plexus drain?
posterior intercostal and mediastinal nodes
Where do the posterior intercostal and mediastinal nodes drain to?
thoracic duct and/or bronchomediastinal trunks
What is the descending thoracic aorta continuous with?
What vertebrae levels does the descending thoracic aorta run along?
extends from T4-12
What is at the level of T4-12 vertebrae?
aortic hiatus in diaphragm
Where does the descending thoracic aorta deviate?
from left toward midline
What are the branches of the descending thoracic aorta in the thorax (posterior mediastinum)?
mediastinal arteries to lymph nodes
How many pairs of posterior intercostal areteries are there from the descending thoracic aorta?
What do the 8 pairs of posteiror intercostal arteries supply?
intercostal spaces 3-11
How many subcostal arteries are there?
Where does the azygos system of veins collect blood from?
posterior intercostal spaces
Are the azygos system of veins fairly consistent from one body to the next?
no, considerable individual variation
Where does the azygos system of veins commence (begin)?
at inferior vena cava
Where does the azygos system of veins ascend?
along vertebral bodies
Where does the azygos system of veins terminate?
in superior vena cava (arches over right main bronchus)
Where are the hemiazygos veins?
on left side of aorta
What are the hemiazygos veins tributaries to?
What are the tributaties to the azygos system of veins?
Does the right recurrent laryngeal nerve enter the thorax?
no, it is only in the nck
Which nerve is next to the ligamentum arteriosum?
left recurrent laryngeal N
What was the ligamentum arteriosum in the embryo?
ductus arteriosus (vessel in embryo that closes off to form ligament)
What is the thymus gland important in?
in immune system
When is the thymus gland large?
What is the size and shape of the thymus in newborns?
What do doctors called large thymus glands in newborns?
Within the first years of life, T-cells in the thymus leave the gland to go where?
to other lymphatics throughout body to set up clones to produce T-cells
After migration of the T-cells, what happens to the thymus gland?
gets smaller (happens by age 2 or 3)
After migration, what is left of the thymus gland?
fatty connective tissue
no functional thymic tissues
Which arteries supply thymus gland?
internal thoracic arteries, not aorta
Where is the boundary line between the superior and inferior mediastinum?
line between aorta and pulmonary trunk
Does the trachea go into inferior mediastinum?
no, because it splits before