3.2.3. ANATOMY - Posterior mediastinum

Question 8

What are the openings of the diaphragm?

Answer 8

Aortic hiatus

Esophageal hiatus

Hiatus of the Vena Cava

Question 9

What are the branches of the thoracic Aorta?

Answer 9

Visceral

1. Pericardial
2. Bronchial
3. Esophageal
4. Mediastinal

Parietal

1. Intercostal
2. Subcostal
3. Superior Phrenic

Question 10

What/where is the ligament of treitz and what do we use it for surgically?

Answer 10

The Ligament of Treitz (“suspensory muscle of the duodenum”) is a slip of muscle from the right crus of the esophageal hiatus of the diaphragm that joins smooth muscle that encircles the horizontal & ascending portions of the duodenum. It is an important surgical landmark that demarcates the duodenum from the jejunum.

Question 11

Where is the first, most superior constriction of the esophagus naturally?

Answer 11

The first constriction is at 15 cm from the upper incisor teeth, where the esophagus commences at the cricopharyngeal sphincter; this is the narrowest portion of the esophagus and approximately corresponds to the sixth cervical vertebra

Question 12

Where is the 2nd constriction of the esophagus?

Answer 12

The second constriction is at 23 cm from the upper incisor teeth, where it is crossed by the aortic arch and left main bronchus

Question 13

Where is the third constriction of the esophagus?

Answer 13

The third constriction is at 40 cm from the upper incisor teeth, where it pierces the diaphragm; the lower esophageal sphincter (LES) is situated at this level

Question 14

Where is the fourth esophagus constriction?

Answer 14

There isn’t one. Just 3 of them.

Question 15

What is the cisterna chyli?

Answer 15

Cisterna chyli - dilated sac at the lower end of the thoracic duct into which lymph from the intestinal trunk and two lumbar lymphatic trunks flow

Question 16

Where does the lymph duct originate?

Answer 16

The lymph duct originates in the abdomen from the confluence of the right and left lumbar trunks and the intestinal trunk, forming a significant pathway upward called the cisterna chyli.

Question 17

What does the thoracic duct do after it has gone upwards past the cisterna chyli?

Question 18

After the thoracic duct traverses the diaphragm at the aortic aperture and ascends the superior and posterior mediastinum between the descending thoracic aorta (to its left) and the azygos vein (to its right), what does it do? Where does it dump?

Answer 18

The duct extends vertically in the chest and curves posteriorly to the left carotid artery and left internal jugular vein at the T5 vertebral level to empty into the junction of the left subclavian vein and left jugular vein, below the clavicle, near the shoulders.

Question 19

What do you do with a lacerated thoracic duct?

Answer 19

When the duct is lacerated, you need to ligate it surgically

Question 20

What are the azygos veins?

Answer 20

The azygos vein transports deoxygenated blood from the posterior walls of the thorax and abdomen into the superior vena cava

Question 21

On an xray, when are the ribs most easy to see and how are they angled when comparing posterior and anterior aspects of the ribs?

Answer 21

Posterior ribs are mostly horizontal and anterior come in at an angle. Anterior ribs are easiest to see from a lateral film view but can be seen on the frontal view

Question 22

How do you know if an object was inhaled vs. swallowed on an xray?

Answer 22

Imagine a coin on an xray. Typically, in the esophagus the item will line up coronally (coin will look like a circular coin). If in the trachea due to the horseshoe shaped cartilage, items will line up sagittally (a coin would look like a line)

Question 23

Describe the positioning of the trachea and primary bronchi on a chest xray

Answer 23

Trachea is for breathing…Nick…leads into the bronchi. The right bronchus that leads into the upper lobe is the highest, see above. The left bronchus divides in the hilium

Question 24

When something is breathed in, where will we see it on the xray?

Answer 24

The right intermediate bronchus is basically a straight shot from the trachea, so something breathed in, like sand or a pen cap, will go mostly to the RLL. Very rarely to left because that bronchus goes about 90 degrees to enter its lung.

Question 25

What is the Carina?

Answer 25

Carina - carina is a cartilaginous ridge within the trachea that runs antero-posteriorly between the two primary bronchi at the site of the tracheal bifurcation

Question 27

How is the esophagus related in position to the heart and trachea?

Answer 27

The esophagus is posterior to the trachea and heart

Question 28

What center structure is illuminated here? What is causing it to be illuminated?

Answer 28

It’s a neon light that this guy swallowed.

No actually it’s Barium lighting up the esophagus.

Question 29

What changes do we need to make in order to visualize the esophagus properly during a chest xray? What else can we see with this alteration?

Answer 29

To image the esophagus you need to look at it obliquely, LAO and RAO views. LAO (left anterior oblique view) “Left aorta open” = you can see all of the branches of the aorta. The RAO (Right anterior oblique) to see the other side of the esophagus. Both are necessary and great for barium swallows.

Question 30

When you sleep drunk, how should you do it and why?

Answer 30

Interesting note, sleep drunk on your right side to drain the booze to the left side away from the fundus and esophagus so that you will not aspirate

Question 31

What is Achalasia?

Answer 31

Dilation of the esophagus caused by a failure of the smooth muscle in the EG (esophageal gastric) sphincter to relax, causing backup.

Question 32

What are we worried about breaking, besides the car, in a patient whose been in a car accident?

Answer 32

Right between the arch and the descending aorta is your ligamentum arteriosum, can break in someone who has a car accident

Question 33

Describe what we are worried about with a lengthy aortic dissection and how we refer to an aorta in this state on chest films.

If you can recall, how did the 22 y.o. soldier present when he had aortic dissection?

Answer 33

Active duty 22 y.o. had an aortic dissection, presented with abdominal pain but had a huge rupture going around the arch and all the way down the descending aorta. Patient’s x-ray showed a “tortuous” aorta, which is where you get those dilations going down. Very dangerous, especially if you rupture some of the smaller arteries coming off of the aorta, which feed into the kidneys, liver, etc

Question 34

Tell me everything about the Azygous veins (where it drains, what drains into it, purpose.

Answer 34

The azygos vein is a vein running up the right side of the thoracic vertebral column draining itself towards the superior vena cavae. It connects the systems of superior vena cava and inferior vena cava and can provide an alternative path for blood to the right atrium when either of the venae cavae is blocked. Feeding into this vein majorly are the intercostal veins.

Question 35

How does the azygous vein present on chest films?

Answer 35

Azygous vein on frontal CXR should be the size of an almond, any larger could be back up in that vein.

Question 36

Where is the azygous vein with respect to the spine and esophagus?

Question 37

Describe the exact position of the arch of the azygous vein

Answer 37

Around right side of the trachea

Above the right main bronchus

enters posterior SVC

Question 38

Describe the branches of the aortic arch

Question 39

What is the Aortopulmonary window/notch?

Answer 39

Aortopulmonary window/notch = a little bit of lung that “pooches in” between the aorta and the pulmonary artery, which sits at the aorta’s 5 o clock above the bronchial tree. The lung juts in a little here.

Question 40

Where are your systemic veins?

Answer 40

Anterior to the arteries and trachea, on the right margin of the mediastinum. The SVC is formed at the level of the aortic arch by the union of the brachiocephalic veins

Question 41

What direction does blood flow?

Answer 41

Left and anterior…always

Whatever that means.

Question 42

This structure makes up the entire right border of the heart.

Answer 42

Right atrium

Question 43

What chamber is the most anterior chamber?

Answer 43

Right ventricle

Question 44

What chamber is the most posterior chamber?

Answer 44

Left atrium

Question 45

What chamber is not bordered by the lungs in any direction?

Answer 45

In class he said the Right atrium but since this makes up the entire right border of the heart, this is obviously not true.

Since the Right ventricle sits on top of the diaphragm, I’m pretty sure that is what they meant.

Question 46

Which chamber has minimal contact with the lungs?

Answer 46

Left atrium

Question 47

What chamber makes up the entire left border of the heart?

Answer 47

Left Ventricle

Question 48

What are these structures?

Question 49

Describe the positioning of the pulmonary arteries

Answer 49

Pulmonary arteries - Main origin anterior from RV, passes under aortic arch

Left passes over the left main bronchus, highest branch of the system

Right is straight lateral from the origin

Question 50

Compare the location of the pulmonary veins to that of the pulmonary arteries

Answer 50

Pulmonary Veins - Confluence inferior and posterior to origin of the arteries.

Question 51

In class, we were shown at the very end a frontal chest xray that had a blotchy looking right cardiac border. Discuss how it should look and what this could be indicative of.

Answer 51

He showed a frontal chest x ray, which showed a blotchy looking right cardiac border, which should be sharp. This was a right middle lobe pneumonia.