Mediastinum/Pericardium

Question 1

What are the divisions of the mediastinum, and what separates them?

Answer 1

Superior

Inferior

• Anterior
• Middle
• Posterior

Superior and Inferior separated by Angle of Louis/Inferior border T4

Question 2

What are the boundaries of the Superior Mediastinum? Contents?

Answer 2

Boundaries:

• Posterior to manubrium
• Anterior to Vertebral column
• Runs anterior to first 4 Thoracic Vertebrae

Contents:

• Aortic Arch (Including BrachioCephalic trunk and left subclavian/LCC
• BrachioCephalic veins
• Thymys
• Esophagus/trachea
• Thoracic Duct
• Vagus/Phrenic Nerves

Question 3

What accompanies the Phrenic Nerve?

Answer 3

Pericardiophrenic artery

Question 4

How do the Right/left phrenic nerves run?

Answer 4

Right: Right of SVC and RA

Left: Lateral to left vagus and AA

Both: Anterior to Root of lung between parietal pleura and fibrous pericardium

Question 5

What are the borders and contents of the Anterior Inferior Mediastinum?

Answer 5

Boundaries: Extends from the posterior surface of the sternun to the anterior surface of the pericardial sac

Contents: Fat, Pericardium, Primary Bronchi, great vessels, and phrenic nerve

Question 6

What are the borders and contents of the Posterior Inferior Mediastinum?

Answer 6

Boundaries: Located posterior to the
pericardial sac and
diaphragm, and anterior
to the bodies of the
inferior eight thoracic
vertebrae (T5-T12)

Contents

• Esophagus
• Thoracic Aorta
• Thoracic Duct
• Azygos Veins
• Vagus and Splanchnic Nerves

Question 7

What are the contents of the middle mediastinum?

Answer 7

• Heart and Pericardium
• Main Bronchi
• Great vessels
• Phrenic Nerve

Question 8

Which pathologies cause contralateral tracheal deviations? Ipsilateral?

Answer 8

Contralateral:

• Tension Pneumothorax
• Pleural effusion
• Hemothorax
• Large Masses

Ipsilateral:

• Atelectasis
• Pneumonectomy
• Large Pleural fibrosis

Question 9

Where is the Pericardium located?

Answer 9

Middle Media Stinum:

• Posterior to Sternum + CC 2-6
• Anterior to T5 - T8 Vertebrae

Question 10

What are the ligamentous attachments for the pericardium?

Answer 10

Sternum —> Sternopericaardial ligament

Diaphragm —> Pericardiophrenic ligament

Question 11

Which pericardium is reflected onto the heart where it forms the epicardium?

Answer 11

Visceral Pericardium

Question 12

Describe the layers of penetration for the pericardium and heart.

Answer 12

Fibrous Pericardium
Parietal layer serous sac
Pericardial cavity
Visceral Layer Serous sac (Epicardium)
Endocardium 
Chamber of the heart

Question 13

What are the two sinuses of the heart?

Answer 13

Transverse Sinus: Behind theAorta and Pulmonary trunk, and in front of LA and Sup Vena Cava.

Oblique Sinus: Between the pulmonary veins and inferior Vena Cava

Question 14

What is the innervation and blood supply for the pericardium?

Answer 14

Innervation: Phrenic Nerve and Vagus Nerve

• Except Visceral layer —> Coronary plexus

Blood Supply:

• Internal thoracic —> Pericardiophrenic and musculophrenic arteries
• Thoracic Aorta —> Pericardial branches of Bronchial, esophageal, and sup phrenic arteries
• Except for visceral pericardium, —> Coronary arteries of ascending aorta

Question 15

What are the clinical considerations for pericardium?

Answer 15

• Pericardial effusions
• Pericarditis (Friction rub)
• Pericardial Tamponade

Pericardiocentesis —> Large bore needle inserted at left sternal margin ICS 4 or paraxiphoid approach (substernal) to avoid intern thoracic artery

Question 16

How is the heart divided in mediastinum?

Answer 16

Middle inferior Mediastinum

Obliquely and deviated so that 2/3 is left of median plane; 1/3 right of median plane

Question 17

How are the base and apex of the heart positioned in the mediastinum? Which ribs does the heart relate to on the left? Which vertebrae does it extend through?

Answer 17

Base is posterior, apex is inferolateral

Medial ends of ribs 3-5

Posteriorly, Extends from T6-T9

Question 18

What forms the base of the heart?

Where is the Apex located?

Answer 18

Base: Left Atrium

Apex: CC 6/ ICS 5

Question 19

What is the blood supply and branches to the right heart?

Answer 19

Right Coronary

• Right Atrial Branch
• Conal Branch
• Right marginal —> Runs with Small cardiac vein
• Posterior Descending artery —> Runs with Middle cardiac vein

Question 20

What is the blood supply And branches to the left heart?

Answer 20

Left Coronary:

• Circumflex (left marginal)
• Anterior descending; two diagonal branches —> Accompanies great cardiac vein

Question 21

What structures are supplied by the right coronary artery?

Answer 21

• AV/SA Nodes
• Inferoposterior 1/3 septum
• Right Ventricle (Right marginal)
• PDA —> 1/3 RV and 2/3 LV

Question 22

What structures are supplied by the left coronary artery?

Answer 22

• LAD —> LV, RV, and anterior 2/3 septum
• AV Bundle
• Circumflex —> LA/LV
• Marginal —> LV

Question 23

What are the Astomoses of the heart?

Answer 23

• Nodal
• Conus arteriosus
• Circumflex
• ADA
• PDA

Question 24

What venous structure lies within the coronary sinus?

Answer 24

Oblique vein

Question 25

What is the common drainage site for the cardiac veins, and what is the exception?

Answer 25

Coronary Sinus;

EXCEPT
Anterior cardiac veins —> Vena Cordis minimal —> RA

*** VCM is NOT a tributary of the coronary sinus

Question 26

What is the ligamentum arteriosus? What is significant about it?

Answer 26

• Vestigial duct which communicates the AA with Pulmonary trunk or left Pulmonary artery
• Left recurrent laryngeal nerve (Vagus) wraps under the ligament (Lateral to) at angle of Louis

Question 27

How does the vRight recurrent laryngeal (vagus) Nerve associate to right subclavian?

Answer 27

Passes under Right subclavian