🪴 GoDeep
Search
← University Challenge
🫀

Anatomy · Heart & blood vessels

Mitral valve

The only heart valve with two cusps

Heart · left atrioventricular valve

The valve between the left atrium and left ventricle, also called the bicuspid or left atrioventricular valve. It has two cusps, anterior and posterior, held by chordae tendineae to two papillary muscles so that they cannot flip back into the atrium when the ventricle contracts. Its name comes from its resemblance to a bishop's mitre.

How to spot them

  • ▸Two leaflets: a large anterior (aortic) cusp and a smaller, scalloped posterior cusp
  • ▸Chordae tendineae to the anterolateral and posteromedial papillary muscles of the left ventricle
  • ▸Supported by a fibrous ring, the annulus, and continuous with the aortic valve via the anterior cusp
  • ▸Best heard at the apex, in the fifth intercostal space at the midclavicular line

What to know

The only valve of the heart with just two cusps

Mitral valve — also called the bicuspid valve.

Named after the pointed headdress of a bishop, which its two cusps resemble when open

Mitral valve — the mitre.

Lies between the left atrium and left ventricle, guarding the entry to the chamber with the thickest wall

Mitral valve — the left atrioventricular valve.

Its cusps are tethered by tendinous cords to two papillary muscles so they cannot prolapse into the atrium in systole

Mitral valve — chordae tendineae and papillary muscles.

Narrowing of this valve, classically from rheumatic fever, causes a mid-diastolic rumbling murmur heard at the apex

Mitral valve — mitral stenosis.

Its anterior cusp lies in fibrous continuity with the aortic valve, forming part of the 'skeleton' of the heart

Mitral valve — aortomitral continuity.

The valve most often replaced or repaired for regurgitation, which gives a pansystolic murmur radiating to the axilla

Mitral valve — mitral regurgitation.

Key ideas

  • Cusps open passively as left atrial pressure exceeds ventricular pressure and slam shut when the ventricle contracts; the papillary muscles contract with the ventricle to stop the cusps inverting.
  • The closure of this valve and the tricuspid valve makes the first heart sound (S1).

Quick-fire facts

  • •Two cusps: anterior (aortic) and posterior (mural); the anterior is larger but the posterior has the longer attachment to the annulus.
  • •Also known as the bicuspid valve or left atrioventricular valve.
  • •Rheumatic heart disease is the commonest cause of mitral stenosis worldwide.
  • •Mitral valve prolapse affects around 2–3% of the population and is usually benign.
  • •The mitral area for auscultation is the apex, at the fifth intercostal space in the midclavicular line.
  • •Its closure produces the M1 component of the first heart sound.
  • •The normal valve area is about 4–6 cm2; severe stenosis is usually defined as below about 1.5 cm2.
  • •Two papillary muscles, anterolateral and posteromedial, hold it via chordae tendineae.

Drill it — 7 cards

1 / 7new card

Sources