Anatomy of the Mediastinum

Question 1

From an anterior view, the esophagus is…
a) anterior to the trachea
b) posterior to the trachea

Answer 1

b) posterior to the trachea

Question 2

The 3 branches of the aortic arch are..

Answer 2

1. Brachiocephalic trunk
2. Left common carotid
3. Left subclavian artery

Question 3

The branchiocephalic trunk branches out into… (2)

Answer 3

1. Right common carotid
2. Right subclavian

Question 4

The superior vena cava branches out into… (2)

Answer 4

1. Left brachiocephalic vein
2. Right brachiocephalic vein

Question 5

The brachiocephalic veins further branch out into… (2)

Answer 5

Internal jugular veins and subclavian veins

Question 6

Where can you find the arch of the azygous vein?

Answer 6

In the superior mediastinum, drains into SVC.

Question 7

What important lymphatic structure is located in the superior mediastinum?

Answer 7

Thoracic duct (on the left side)

Question 8

What is the function of the thoracic duct? Where does it drain?

Answer 8

Returns 75% of total lymphatic fluid to venous circulation. It drains at the venous angle between the left subclavian and the left internal jugular veins.

Question 9

What is the main nerve found in the superior mediastinum?

Answer 9

Vagus nerve (running down both on the left and right).

Question 10

Which laryngeal nerve has a longer course? What do they branch off of?

Answer 10

The left laryngeal nerve is longer than the right. Both branch off the vagus nerve (L&R).

Question 11

Which laryngeal nerve passes through the superior mediastinum, and which does not?

Answer 11

Left laryngeal nerve has a portion in the superior mediastinum, the ight does not.

Question 12

The vagus nerve is also known as…

Answer 12

the cranial nerve X

Question 13

In the superior mediastinum, the vagus nerve gives rise to…

Answer 13

parasympathetic nerves that contribute to the cardiac and pulmonary plexuses.

Question 14

What do laryngeal nerves innervate?

Answer 14

Laryngeal nerves innervate most laryngeal muscles (muscle of the larynx).

Question 15

Impingement of laryngeal nerves can lead to…

Answer 15

hoarseness or dysphonia.

Question 16

The left laryngeal nerve branches off the vagus and loops under…

The right laryngeal nerve branches off the vagus and loops under…

Answer 16

The left laryngeal nerve branches off the vagus and loops under the AORTIC ARCH.

The right laryngeal nerve branches off the vagus nerve and loops under the BRACHIOCEPHALIC TRUNK or RIGHT SUBCLAVIAN.

Question 17

The anterior mediastinum is primarily occupied by…

Answer 17

the thymus gland

Question 18

What is the function of the thymus gland?

Answer 18

Organ of the lymphatic system, responsible for the differentiation of T cells.

Question 19

How does the thymus gland change with age?

Answer 19

Because it is involved with immune system development, it will be larger in childhood/youth and will degenerate in adults (becomes fibro-fatty tissue).

Question 20

What are the 5 important components of the middle mediastinum?

Answer 20

1. Heart
2. Neurovasculature outside the pericardium (phrenic nerve, pericardiacophrenic arteries and veins)
3. Neurovasculature inside the pericardium (cardiac plexus, coronary circulation)
4. Roots of great vessels
5. Primary bronchi

Question 21

How come the posterior mediastinum communicates freely with the superior mediastinum?

Answer 21

Because many structures are continuous between these two compartments, e.g. sympathetic chain, vagus nerve, esophagus, aorta, azygos vein, thoracic duct).

Question 22

Which part of the mediastinum houses the descending aorta?

Answer 22

Posterior mediastinum

Question 23

Azygos and hemi-azygos veins drain…

Answer 23

the posterior thoracic and abdominal walls

Question 24

The azygos vein provides a collateral passage for venous blood to…

Answer 24

bypass blockages in the vena cavae

Question 25

The thoracic duct drains 3/4 of the body's lymph. What drains the remaining 1/4?

Answer 25

The right lymphatic duct (into the brachiocephalic veins and at the venous angles)

Question 26

The thoracic portion of the aorta gives rise to...

Answer 26

the posterior intercostal arteries from rib 3 to 12

Question 27

Posterior intercostal arteries anastomose with

Answer 27

anterior intercostal arteries

Question 28

Posterior intercostal arteries are found between what muscle layers?

Answer 28

Internal and innermost intercostal muscles

Question 29

The esophagus passes through the diaphragm at the level...

Answer 29

T10

Question 30

The esophagus is a muscular tube that connects the ... to...

Answer 30

connects the pharynx to the stomach

Question 31

Which subdivisions of the mediastinum does the esophagus run through?

Answer 31

The superior and posterior mediastinum

Question 32

How is the esophagus positioned relative to the aorta in the posterior meidastinum?

Answer 32

At first, it is to the right of the aorta, but then moves anterior to the aorta and through the diaphragm.

Question 33

The opening in the diaphragm for the esophagus is called...

Answer 33

esophageal hiatus

Question 34

As they enter the posterior mediastinum, the vagus nerves pass... a) anterior to the hilum of the lungs b) posterior to the hilum of the lungs

Answer 34

b) posterior to the hilum of the lungs

Question 35

Below the hilum of the lungs: The right vagus nerve becomes... The let vagus nerve becomes...

Answer 35

The right vagus nerve becomes the posterior vagal trunk. The left vagus nerve becomes anterior vagal trunk. *LARP mnemonic*