Mediastinum

Question 1

Mediastinum

Answer 1

Everything between the right and left pleural sacs bounded by mediastinal pleura
Extends from the thoracic inlet to the diaphragm
NOT A CLOSED CAVITY!

Question 2

What are the three Mediastinal reflections?

Answer 2

Cranioventral
Caudoventral
Caval

Question 3

Cranioventral mediastinal reflection

Answer 3

border between the right cranial lung lobe and the cranial part of the left cranial lobe

Question 4

What does the thymus look like in a VD?

Answer 4

A sail!

Question 5

Caudoventral mediastinal reflection

Answer 5

border between the accessory lobe and the left caudal lobe

Question 6

What lives in the Caudoventral mediastinal reflection?

Answer 6

The phrenic nerve

Question 7

What lives in the Cranioventral mediastinal reflection?

Answer 7

Thymus

Question 8

What mediastinal organs are visible?

Answer 8

Heart
Trachea
Caudal Vena Cava
Aorta
Thymus
Esophagus

Question 9

What mediastinal organs are NOT visible?

Answer 9

Cranial Vena Cava
Azygos vein 
Lymph nodes
Nerves
Small arteries and veins

Question 10

Which do you see on radiographs, Cranial or Caudal Vena Cava?

Answer 10

Caudal Vena Cava!

Question 11

What causes Mediastinal shift?

Answer 11

Atelectasis

Question 12

How do you dissociate Atelectasis from Lung Disease?

Answer 12

Lung opacity, no heart shift = disease

Lung opacity, heart shift = atelectasis

Question 13

What could be the reason for a cranioventral mediastinal mass?

Answer 13

Mediastinal LN
Thymus
Sternal LN
Cyst

Question 14

What could be the reason for a hilar mediastinal mass?

Answer 14

Tracheobronchial LN
Left Atrium
Heart Base tumor

Question 15

What could be the reason for a dorsal mediastinal mass?

Answer 15

Esophagus

Question 16

What do the Cranial Mediastinal Lymph nodes drain?

Answer 16

Thoracic wall
Trachea
Thyroid

Question 17

What do the Tracheobronchial Lymph nodes drain?

Answer 17

Lungs

Question 18

What do the Sternal Lymph nodes drain?

Answer 18

Mammary glands
Thoracic wall
peritoneum

Question 19

What could an enlarged sternal lymph node mean?

Answer 19

Peritoneal disease
Hemorrhage
Ruptured Splenic Tumor

Question 20

What does the “Bow Legged Cowboy” sign mean when seen on a radiograph?

Answer 20

The tracheobronchial lymph node has swollen

Question 21

Can you see a mediastinal mass with pleural fluid?

Answer 21

NO! DRAIN THE FLUID AND RE-RADIOGRAPH!

Question 22

How does the trachea appear with Tracheobronchial Lymphomegaly?

Answer 22

Ventral angulation of the tracheal bifurcation

Question 23

What happens to the trachea when the left atrium is enlarged?

Answer 23

The trachea is angled upward

Question 24

What happen to structures with Pneumomediastinum?

Answer 24

structures become more conspicuous that you wouldn’t normally see
Ex: Azygous vein

Question 25

What happens if Pneumomediastinum progresses?

Answer 25

Pneumothorax

Question 26

Can Pneumothorax progress to Pneumomediastinum?

Answer 26

NO!

Question 27

What view is the best to see Pneumomediastinum?

Answer 27

Lateral view

Question 28

What two ways can cause Pneumomediastinum?

Answer 28

Retrograde slow along the airways from intrapulmonary rupture Hole in Trachea Neck wound

Question 29

What causes a hole in the trachea?

Answer 29

Bite wound Jugular vein puncture Transtracheal aspirate Endotracheal tube cuff overinflation

Question 30

Macklin effect

Answer 30

gas in the lung parenchyma getting out of the bronchi and vessels and into the mediastinum

Question 31

Which structures become visible with Pneumomediastinum?

Answer 31

Adventitial border of the trachea Ascending aorta Left Subclavian artery Brachiocephalic trunk

Question 32

What other clinical signs can you see with Pneumomedistinum?

Answer 32

Air under the skin - "crunchy" feeling | Animal appears twice its normal size

Question 33

What are the different types of fluid seen in the mediastinum?

Answer 33

Hemorrhage | Exudate