Anatomy of CVS

Question 1

What are the anatomical borders of the mediastinum?

Answer 1

Region between the lungs:
AP: sternum - body of vertebra
SI: superior thoracic aperture - diaphragm
Lungs on the sides

Question 2

What are the contents of the anterior mediastinum?

Answer 2

Sternopericardial ligaments: connect sternum to the fibrous pericardium,
thymus (children)
thoracic artery + branches
Lymphatics

Question 3

What’s in the middle mediastinum?

Answer 3

The heart

Question 4

What surrounds the heart and what structure is just underneath it?

What could happen to this structure that might make the heart stop beating?

Answer 4

The fibrous pericardium is the tough CT layer that covers the heart
The serous layer has a visceral and parietal layer:
-Parietal; adheres to the fibrous pericardium
-Visceral: surrounds the heart
Between them is the pericardial cavity: has lubricating fluids that allow for movement of the heart
*Any leaking blood will fill up the pericardial bag/cavity - if it reaches a certain volume it can stop the heart from beating.

Question 5

What’s in the posterior mediastinum?

What is it particularly susceptible to?

Answer 5

thoracic (descending) aorta, azygous vein, thoracic duct, esophagus, posterior mediastinal lymph nodes, VAGUS and splanchnic nerves

It’s a large communication channel; so it’s more susceptible to tumours, infection, etc.

Question 6

What is mediastinitis? Name one sign and three possible symptoms

Answer 6

Mediastinitis: inflammation of the mediastinum
Sign: entire mediastinum may shift due to fluid buildup

Symptoms: SOB, difficulty swallowing, hoarse voice

Question 7

What’s the thymic sail sign? What can it be confused with?

Answer 7

A ‘sailship’ looking silhouette on an X-ray that indicates the thymus, can be confused with fluid accumulation

Question 8

Describe the pathway of the VAGUS N going inferior -> superior

Answer 8

Travels through mediastinum: posterior to lung roots and anterior to subclavian, forms “vagal fibres”/plexus around the esophagus and the R descends posteriorly/L descends anteriorly up the esophagus

Question 9

What does the phrenic N supply?

Answer 9

The diaphragm and the pericardium

Question 10

What’s the transverse pericardial sinus, what can it be used for in surgery?

Answer 10

Passageway that is posterior to the arterial output/pulmonary trunk and anterior to the superior vena cava
Can be clamped in surgery to stop arterial blood flow

Question 11

What happens if you have damage to the papillary muscles?

Answer 11

Valve incompetence and cardiac murmur

Question 12

Name 3 things that aid the valves?

Answer 12

Chordiae tendinae, papillary muscles, cardiac fibrous skeleton (high-density fibrous structure of CT that forms and anchors the valves)

Question 13

What prevents electrical signals from being mixed between the atria and ventricles?

Answer 13

Fibrous Tissue

Question 14

Describe the structure of aortic/pulmonary valves and how they open and close

Answer 14

3 cusps: semilunar
Diastole: The backwards flow of blood fills up pockets/cusps, expanding them and closing the valve

Systole: rapid ejection of blood pushes the cusps against the vessel wall, opening the valve

Question 15

Where does the L coronary artery start and what can branch off of it?

Answer 15

LCA arises from the aorta above the L cusp of the aortic valve

Gives off:
1. Widowmaker: Anterior interventricular artery/L anterior descending: supplies the bulk of R and L ventricles, anterior 2/3rds of the septum and AV node in 20%

3. Circumflex; L atrium and ventricle; continues as PIVA in 40% of people which supplies the AV node in 20%

Question 16

What can branch of the R coronary artery and where does it start?

Answer 16

Above R anterior cusp

1. PIVA in 60%; AV node in 80% and posterior 1/3 of the septum
2. Sinoatrial node artery: SA node, R and L atria
3. Marginal artery; reaches the apex

Question 17

Where does the bulk AND the minority of cardiac venous drainage go through?

Answer 17

Bulk: coronary sinus

Minority: some anterior veins are independent of the coronary sinus and drain directly into the R atrium

Question 18

What are venae cordis minimi?

Answer 18

Little direct openings in the heart wall that return venous drainage directly into heart chambers

Question 19

Where should the apex of the heart be on a chest?

What does it mean if the apex is somewhere else?

Answer 19

3.5 inches away from the midline in 5th ICS

If it’s lower, it indicates heart has enlarged due to being overworked (not good)

Question 20

Which intercostal spaces and heart chambers make up the bulk of the R and L sides of the heart?

Answer 20

L: 2-5 ICS, L ventricle
R: 3-6 ICS, R atria

Question 21

Where do you auscultate for each valve?

Answer 21

Mitral Valve: 5th ICS, Left mid-clavicular line
Tricuspid: 4th ICS, left sternal border
Pulmonary: L sternal edge, 2nd ICS
Aortic: R sternal edge, 2nd ICS

Question 22

What was the fossa ovalis? What was it used for?

Answer 22

Was the foramen ovale that functioned as the shunt between the fetal R and L atria

Question 23

Why are there rough and smooth surfaces in the R and L atrium?

Answer 23

Rough is the original portion, and smooth is where other vessels have been pulled into the chamber:
R atria: Smooth where the venae cava were pulled in
L atria: smooth where the pulmonary veins have been pulled in

Question 24

What’s the conus arteriosus and what did it develop from?

Answer 24

smooth wall part in the R ventricle, develops from the bulbus cordis

Question 25

What does the ligament arteriosum do and what is it the remnant of?

Answer 25

Holds the aorta and pulmonary artery close together, a remnant of the ductus arteriosus

Question 26

Name which nerves give sympathetic and parasympathetic innervation to the heart, which is associated with referred cardiac pain?

Answer 26

Sympathetic: T1-T4 derived parts of the sympathetic chain, associated with referred cardiac pain: as cardiac visceral sensory fibres travel back to CNS with sympathetic nerves

Parasympathetic: VAGUS n, cardiac branches mainly arise in the thorax and post-ganglionic fibres arise from ganglia on the heart

Question 27

What does the fibrous pericardium bind to inferiorly?

Answer 27

The central diaphragmatic tendon (also a boundary of most middle mediastinum)

Question 28

What symptoms can result from decreased perfusion to the R coronary?

Answer 28

Since the R coronary artery supplies the SA node, decreased perfusion can cause an arrhythmia and bradycardia

Question 29

Which vertebral level is a deep injury detrimental?

Answer 29

T4/T5 - 2nd costal cartilage

Question 30

Overall, what do the R and L coronary normally supply?

Answer 30

R: R atria and ventricle, SA node, AV node, posterior IV septum

L: atria and ventricle, anterior IV septum and AV bundle