Mediastinum 2 (Maria)

Question 1

Where does the vagus nerve (R/L) enters the superior mediastinum?

Answer 1

They enter posterior to the respective sternoclavicular joint and branchiocephalic vein.

Question 2

Where does the right vagus nerve enters the thorax, and what does it give rise to?

Answer 2

It enters anterior to the right subclavian artery and it gives rise to the right recurrent laryngeal nerve.

Question 3

The right recurrent laryngeal nerve innervates the _______

Answer 3

Larynx.

Question 4

True or False:

The right vagus nerve passes anteriorly to the right brachiocephalic vein, superior vena cava, and root of the right lung.

Answer 4

False, it passes posteriorly.

Question 5

Going from superior to inferior, the right vagun nerve is part of what plexuses?

Answer 5

First right pulmonary plexus and then esophageal plexus and cardiac plexus.

Question 6

Where does the left vagus nerve enters the mediastinum?

Answer 6

It enters between the left common carotid artery and left subclavian artery.

Question 7

What nerves does the left vagus nerve give rise to and where?

Answer 7

The left vagus nerves gives rise to the left recurrent laryngeal nerve when it curves medially at the inferior border of the aorta.

Question 8

What does the phrenic nerve innervates and where does it enters through?

Answer 8

1. Innervation:

• Diaphragm with motor and sensory fibers
• Pericardium and mediastinal pleura with sensory fibers.

2. Enters between the subclavian artery and the origin of the branchiocephalic vein

Question 9

What helps you distinguish the phrenic nerve from the vagus nerve?

Answer 9

The phrenic nerve pass anteriorly to the roots of the lungs while the vagus nerve pass posteriorly to the roots of the lungs.

Question 10

True or False:

The right phrenic nerve passes along the right side of the right brachiocephalic vein, superior vena cava, and pericardium over the right atrium.

Answer 10

True

Question 11

True or False:

Most branching of the phrenic nerves for distribution to the diaphragm occurs on the diaphragm’s inferior (abdominal) surface.

Answer 11

True

Question 12

True or False:

Left phrenic nerve crosses the left surface of the arch of the aorta posterior to the left vagus nerve.

Answer 12

False, it passes anterior to the left vagus nerve

Question 13

What does the recurrent laryngeal nerves innervate?

Answer 13

They innervate all intrinsic muscles of the larynx, except cricothyroid

Question 14

If you have an injury to the recurrent laryngeal nerves, what is affacted?

Answer 14

• voice
• It may be involved in bronchiogenic or esophageal carcinoma
• enlargement of mediastinal lymph nodes
• aneurysm of the arch of the aorta.

Question 15

At what level does the trachea ends?

Answer 15

It ends at the level of the sternal angle by diving into right and left bronchi and superior to the level of the heart.

Question 16

Where does the esophagus enters the superior mediastinum?

Answer 16

It enters the superior mediastinum between the trachea and the vertebral column, where it lies anterior to the bodies of the T1-T4 vertebrae.

Question 17

True or False:

The esophagus is compressed posteriorly by the root of the right lung.

Answer 17

False. The esophagus is compressed anteriorly by the root of the left lung.

Question 19

True or False:

Inferior to the arch, the esophagus again inclines to the left as it approaches and passes through the esophageal hiatus in the diaphragm.

Answer 19

True.

Question 20

Where does the esophagus enters the diaphragm and at what level of the vertebral column?

Answer 20

Enters the esophageal hiatus at the T10 level, anterior to the aorta.

Question 21

The esophagus is compressed by what structures? and how can they be observed?

Answer 21

A. Compressed by:

1. arch of the aorta
2. left main brochus
3. diaphragm

B. Can be observed in a oblique chest radiograph, using barium.

Question 22

Why are impression on the esophagus by adjacent structures is of clinical interesr?

Answer 22

Because since there is a slower passage of substance at these sites, this impression indicate where swallowed foreign obects are most likely to lodge and where a stricture may develop after the accidental drinking of a caustic liquid such as lye

Question 23

What are the borders of the anterior mediatinum?

Answer 23

Space between the body of the sternum and the transverse thoracic muscles anteriorly and pericardium posteriorly

Question 24

True or False:

The anterior mediastinum is continuous with the superior mediastinum at the sternal angle and is limited inferiorly by the diaphragm.

Answer 24

True

Question 25

What can you find in the anterior mediastinum of infants and children?

Answer 25

1. loosse CT (sternopericardial ligaments)
2. fat
3. lymphatic vessels
4. branches of internal thoracic vessels
5. inferior part of thymus

Question 26

What are the borders of the posterior mediastinum?

Answer 26

* inferior to the transverse thoracic plane * anterior to the T5-T12 vertebrae * posterior to the pericardium and diaphragm * between the parietal pleura of the two lungs.

Question 27

What can be found in the posterior mediastinum?

Answer 27

* thoracic aorta * thoracic duct and lymphatic trunks * posterior mediastinal lymph nodes * azygos and hemiazygos veins * esophagus and esophageal nerve plexus.

Question 28

Where does the thoracic aorta begins?

Answer 28

## Footnote It begins on the left side of the inferior border of the body of the T4 vertebra and descends in the posterior mediastinum on the left sides of the T5-T12 vertebrae.

Question 29

True or False: The thoracic aorta lies anterior to the root of the left lung, posterior to pericardium, and esophagus.

Answer 29

False, it lies posterior to the root of the left lung, pericardium and esophagus

Question 30

Where the thoracic aorta ends and what does it become?

Answer 30

terminates and becomes the abdominal aorta anterior to the inferior border of the T12 vertebra and enters the abdomen through the aortic hiatus in the diaphragm.

Question 31

True or False: The thoracic duct and azygous veins ascends on the left side of the thoracic aorta and end at the hiatus.

Answer 31

False, the thoracic duct and azygos vein ascend on its right side and accompany it through this hiatus.

Question 32

The branches of the descending aorta arise and course through which three vascular planes?

Answer 32

1. Anterior and midline plane * Unpaired visceral branches * Goes to the gut and its derivatives 2. Lateral plane * Paired visceral branches * serving viscera other than the gut and its derivatives 3. Posterolateral planes * Paired, segmental, parietal branches * Body wall

Question 33

What constitute the unpaired visceral branches of the anterior vascular plane?

Answer 33

Esophageal arteries (2).

Question 34

What constitute the paired visceral branches of the lateral plane?

Answer 34

Bronchial arteries.

Question 35

How is the right bronchial artery different from the left bronchial artery?

Answer 35

The left paired bronchial artery arises directly from the aorta, but the right arises indirectly as branches of a right posterior intercostal artery (3rd one)

Question 36

What constitute the paired parietal branches of the posterolateral plane?

Answer 36

* The 9 posterior intercostal arteries that supply all but the upper two intercostal spaces and the subcostal arteries

Question 37

Although the other vessels arise from the thoracic aorta and course through bellow the diaphragm, there are exception to this. What are they?

Answer 37

1. _The superior phrenic arteries_ are paired parietal branches that pass anterolaterally to the superior surface of the diaphragm, where they anastomose (join) with the musculophrenic and pericardiacophrenic branches of the internal thoracic artery. 2. _Pericardial branches_ are unpaired branches that arise anteriorly but, instead of passing to the gut, send twigs to the pericardium. 3. _The small mediastinal arteries_ supply the lymph nodes and other tissues of the posterior mediastinum.