Atrial and Ventricular Walls

Question 1

Explain the contents of the RA

Answer 1

Pectinate Muscles

Crista Terminalis: Separates pectinate muscles

Sinus Venarum - smooth surface

• sinus of vena cavae
• between 2 vena cavae
• thin walls

Fossa Ovalis:

• within interatrial septum
• after birth, the foramen ovale valve closes creating the fossa ovalis
• Foramen ovale is the opening between the RA and LA

Question 2

Left Atrium contents

Answer 2

Chiefly smooth

Opening which receives pulmonary veins

Valve of foramen ovale

Question 3

Right Ventricle

Answer 3

Trabeculae Carnae - Muscular Ridges

Papillary Muscles - attached to cusps via chordae tendinae
- contract to prevent inversion or prolapse of these valves

Question 4

Left Ventricle

Answer 4

Same as RV

But thicker than RV

Question 5

Mitral Valve:

How many leaflets/cusps, how does it tether to the papillary muscles?

Answer 5

2

Tethered via chordinae tendineae

Question 6

Mitral Valve:

How many papillary muscles and name them

Answer 6

2

Anterolateral
Posteromedial

Question 7

Mitral Valve:

Explain the papillary muscles blood supply

Answer 7

Anterolateral

• has dual blood supply
• LAD + LCX (left circumflex)
• makes it resistant to ischaemia

Posteromedial

• Single blood supply
• RCA (or LCX)

Question 8

Which papillary muscle is most likely to rupture due to an INFERIOR infarction?

Answer 8

leads to the rupture of Posteriomedial papillary muscle

because it only has a single blood supply

leading to:

• Mitral regurgitation
• Acute HF