L-04-Mediastinum-Pericardium-Heart

Question 1

Mediastinum
Q: What is the mediastinum?
Q: What are the boundaries of the mediastinum?
Q: What are the subdivisions of the mediastinum?

Answer 1

A: The central area of the thoracic cavity containing all thoracic viscera except the lungs.

A:
Superior: Thoracic inlet
Inferior: Diaphragm
Anterior: Sternum & costal cartilages
Posterior: Thoracic vertebrae
A:
Superior Mediastinum (above sternal angle, T4-T5)
Inferior Mediastinum (divided into anterior, middle, and posterior parts)

Question 2

Pericardium
Q: What are the two layers of the pericardium?
Q: What are the two layers of the serous pericardium?
Q: What are the two layers of the serous pericardium?

Answer 2

A:
Fibrous pericardium (outer, tough layer)
Serous pericardium (inner, double-layered)
A:
Parietal layer (lines fibrous pericardium)
Visceral layer (epicardium) (covers the heart)
A:
Transverse sinus (behind great arteries)
Oblique sinus (behind the heart, near pulmonary veins)

Question 3

Heart Chambers
Q: What structures are found in the right atrium?
Q: What structures are found in the ventricles?

Answer 3

A:
Fossa ovalis (remnant of foramen ovale)
Openings for SVC, IVC, and coronary sinus
SA node (near SVC opening)
AV node (near coronary sinus opening)
A:
Chordae tendineae: Attach valve cusps to papillary muscles
Trabeculae carneae: Rough muscular ridges in the ventricular walls

Question 4

Heart Valves
Q: What are the four heart valves and their locations?

Answer 4

A:

Tricuspid valve: Between right atrium & right ventricle
Pulmonary valve: Between right ventricle & pulmonary artery
Mitral (bicuspid) valve: Between left atrium & left ventricle
Aortic valve: Between left ventricle & aorta

Question 5

Conducting System of the Heart
Q: What are the key components of the heart’s conduction system?

Answer 5

A:

SA node (pacemaker): Initiates impulse
AV node: Delays impulse
Bundle of His: Carries impulse to ventricles
Purkinje fibers: Spread impulse for ventricular contraction

Question 6

Nerve Supply of the Heart
Q: What is the sympathetic innervation of the heart?
Q: What is the parasympathetic innervation of the heart?

Answer 6

A: From T2-T4 spinal segments, increases heart rate and contraction strength.
A: From the vagus nerve, decreases heart rate and conduction velocity.

Question 7

Blood Supply of the Heart
Q: What are the main coronary arteries and their branches?
Q: What is the main venous drainage of the heart?

Answer 7

A:

Right coronary artery: SA nodal branch, AV nodal branch, right marginal artery, posterior interventricular artery
Left coronary artery: Anterior interventricular (LAD), circumflex artery, left marginal artery
A: Coronary sinus, which drains into the right atrium.

Question 8

Heart Sounds
Q: What causes the “Lub-Dub” heart sounds?

Answer 8

A:

Lub: Closure of AV valves (tricuspid & mitral) at the start of systole
Dub: Closure of semilunar valves (aortic & pulmonary) at the end of systole