Papillary muscle

Papillary muscle
Interior of right side of heart. Papillary muscles labeled in purple.
Diagram showing relations of opened heart to front of thoracic wall.

Ant. Anterior segment of tricuspid valve.
A O. Aorta.
A.P. Anterior papillary muscle.
In. Brachiocephalic artery (Innominate).
L.C.C. Left common carotid artery.
L.S. Left subclavian artery.
L.V. Left ventricle.
P.A. Pulmonary artery.
R.A. Right atrium.
R.V. Right ventricle.
V.S. Ventricular septum.
Details
Identifiers
Latinmusculus papillaris
MeSHD010210
TA98A12.1.00.022
TA24043, 4066
FMA12154
Anatomical terms of muscle

The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae and contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction).[1] The papillary muscles constitute about 10% of the total heart mass.[2]

Structure

There are five total papillary muscles in the heart; three in the right ventricle and two in the left. The anterior, posterior, and septal papillary muscles of the right ventricle each attach via chordae tendineae to the tricuspid valve. The anterolateral and posteromedial papillary muscles of the left ventricle attach via chordae tendineae to the mitral valve.[3]

Blood supply

The mitral valve papillary muscles in the left ventricle are called the anterolateral and posteromedial muscles.[4]

The posteromedial muscle ruptures more frequently because it only has one source of blood supply, hence RCA occlusion can cause papillary muscle rupture.[4]

Function

The papillary muscles of both the right and left ventricles begin to contract shortly before ventricular systole and maintain tension throughout.[1] This prevents regurgitation—backward flow of ventricular blood into the atrial cavities—by bracing the atrioventricular valves against prolapse—being forced back into the atria by the high pressure in the ventricles.[1]

Clinical significance

Papillary muscle rupture can be caused by a myocardial infarct, and dysfunction can be caused by ischemia. Both complications may lead to worsening of mitral regurgitation.[5]

Additional images

See also

References

  1. 1 2 3 Moore KL, Dalley AF, Agur AM (2007). Clinically Oriented Anatomy (3rd ed.). Baltimore: Lippincott Williams & Wilkins. pp. 92, 94. ISBN 978-0-7817-6274-8.
  2. ↑ Fung, Yuan-Cheng (February 1998). "BIOMECHANICS". SHOCK. 9 (2): 155. doi:10.1097/00024382-199802000-00018. ISSN 1073-2322.
  3. ↑ Netter's Atlas of Human Anatomy, plates 216B and 217A
  4. 1 2 Fradley, M. G.; Picard, M. H. (7 March 2011). "Rupture of the Posteromedial Papillary Muscle Leading to Partial Flail of the Anterior Mitral Leaflet". Circulation. 123 (9): 1044–1045. doi:10.1161/CIRCULATIONAHA.110.984724. PMID 21382906.
  5. ↑ Elizabeth D Agabegi; Agabegi, Steven S. (2008). Step-Up to Medicine (Step-Up Series). Hagerstwon, MD: Lippincott Williams & Wilkins. pp. 40. ISBN 978-0-7817-7153-5.
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