Superior/Posterior Mediastinum

Question 1

What section of the aorta is in the superior mediastinum?

Answer 1

Aortic arch

Starts at sternal angle, ends at sternal angle

Question 2

What are the three branches of the aortic arch?

Answer 2

Brachiocephalic

Left common carotid

Left subclavian

Question 3

What are the branches of the thoracic aorta?

Answer 3

9 pairs of posterior intercostal arteries

One pair of subcostal arteries - below rib 12

One pair of superior phrenic arteries

Two left bronchial arteries

Two esophageal arteries

Question 4

What is the level of the aortic hiatus in the diaphragm?

Answer 4

T12

Question 5

What vessels unite to form the brachiocephalic veins?

Answer 5

Internal jugular veins and subclavian veins

Question 6

What does the azygous vein drain blood from?

Answer 6

Right thoracic wall via posterior intercostal veins

Left thoracic wall via hemiaxygous and Accessory hemiazygous

Esophague

Lung tissue

Vertebral column/spinal cord

Question 7

What does the hemiazygous vein drain blood from?

Answer 7

Lower left intercostal spaces

Crosses midline to drain into azygous vein

Question 8

What does the accessory hemiazygous vein drain blood from?

Answer 8

Middle left intercostal spaces

Question 9

What is the collateral pathway to the right atrium?

Answer 9

Azygous vein system provides a collateral pathway if the superior/inferior vena cava is blocked

Question 10

What is superior vena cava syndrome?

Answer 10

Obstruction of superior/inferior vena cava that prevents blood from easily traveling through

Bronchogenic tumor or Liver tumor

Question 11

What is the thoracic duct?

Answer 11

Main lymph channel body receiving all lymph from below the diaphragm and left side of entire body

Ascends through the aortic hiatus between the azygous vein and thoracic aorta, posterior the the esophagus

Question 12

What is the cisterna chyli?

Answer 12

Dilated lymph sac in the abdomen that receives lymph from the small intestine

Question 13

Where does the thoracic duct drain?

Answer 13

Beginning of the left brachiocephalic vein

Question 14

What is the right lymphatic duct?

Answer 14

Drains upper right side of the body

Receives three lymph ducts: Right sublcavian, right bronchomediastinal, and right jugular

Although these three ducts may drain independently*

Question 15

Describe the course of the left phrenic nerve

Answer 15

Enters from neck between left subclavian artery and vein

Crosses the arch of the aorta anterior to the left vagus nerve

Courses anterior to the root of the lung and exits by directly piercing the left dome of the diaphragm

Question 16

Where does the right phrenic nerve exit the middle mediastinum?

Answer 16

Caval opening in the diaphragm with the inferior vena cava

Question 17

What nerve comes off the left vagus nerve and what is the clinical significance?

Answer 17

Left recurrent layrngeal, which hooks underneath the ligamentum arteriosum and the aortic arch

A physician ligating a patent (open) ductus arteriosus in an infant must not ligate the left recurrent laryngeal nerve

Question 18

Describe the path of the right vagus nerve

Answer 18

Enters the SM anterior to the right subclavian artery

Descends lateral to the trachea

Gives off right recurrent laryngeal

Question 19

Where are the left and right vagal trunks located?

Answer 19

Left - anterior side of the esophagus

Right - posterior side of the esophagus

Both pass through the diaphragm with the esophagus

Question 20

How are the branches of the sympathetic ganglia divided?

Answer 20

Upper five - sympathetics which supply vaious thoracic viscera (postganglionic)

Lower five - form three thoracic splanchnic nerves (preganglionic)

Question 21

What are the greater splanchnic nerves?

Answer 21

Arises from fifth to ninth or tenth thoracic ganglia

Descend across the vertebral bodies medially, and passes into the abdomen through the crus of the diaphragm, ends in the celiac ganglion

Question 22

What are the lesser splanchnic nerves

Answer 22

Aris from 9th and 10th or 10th and 11th thoracic ganglia

Descends across the vertebral bodies medially through the crus of the diaphragm

Ends in the aorticorenal ganglion

Question 23

What are the least splanchnic nerves?

Answer 23

Arise from 12th thoracic ganglion

Descends through the crus to end in the renal plexus

Question 24

What is the location and blood supply of the the thymus?

Answer 24

Immediately posterior to the manubrium

Branches of internal thoracic artery and inferior thyroid artery

Question 25

What are the three main differences between the right and left main bronchi and why are they important?

Answer 25

Right - shorter, wider and more vertically oriented

Objects (food) will more likely pass into the right main bronchus

Question 26

Describe the path of the left main bronchus

Answer 26

Crosses anterior to the esophagus and the aorta, may constrict the esophagus

Question 27

What is the carina?

Answer 27

Internal “keel” at the division of the trachea

Important landmark that can be distorted by the tracheobronchial lymph nodes due to bronchogenic carcinoma

Question 28

What are four locations that can cause constriction of the esophagus?

Answer 28

Pharynx narrows

Arch of the aorta

Left main bronchus

Diaphragm

Question 29

What heart problem can cause esophageal compression?

Answer 29

Hypertrophy of the left atrium caused by left-sided heart failure

Can be seed radiographically