The moderator band (also known as septomarginal trabecula) is a band of

cardiac muscle Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall o ...

found in the right ventricle of the

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

. It is well-marked in

sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...

and some other animals, including humans. It extends from the base of the anterior

papillary 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 ...

of the

tricuspid valve The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, at the superior portion of the right ventricle. The function of the valve is to allow blood to flow from the right atrium to the right vent ...

to the

ventricular septum The interventricular septum (IVS, or ventricular septum, or during development septum inferius) is the stout wall separating the ventricles, the lower chambers of the heart, from one another. The interventricular septum is directed obliquely b ...

Structure

The moderator band is located in the right ventricle. The moderator band connects the base of the anterior papillary muscles of the tricuspid valve to the ventricular septum.

Function

The moderator band is important because it carries part of the right bundle branch of the atrioventricular bundle of the conduction system of the heart to the anterior

. This shortcut across the chamber of the ventricle ensures equal conduction time in the left and right ventricles, allowing for coordinated contraction of the anterior papillary muscle.

Clinical significance

The moderator band is often used by radiologists and obstetricians to more easily identify the

right ventricle A ventricle is one of two large chambers located toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium (heart), atrium, an adjace ...

prenatal Prenatal development () involves the embryonic development, development of the embryo and of the fetus during a viviparity, viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic develop ...

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

History

From its attachments it was thought to prevent overdistension of the ventricle, and was named the "moderator band". It was first described by

Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 1452 - 2 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested o ...

in his exploration of human anatomy.

Additional images

File:2008 Internal Anatomy of the HeartN.jpg, Location of the moderator band

References

External links

Videos and photos of moderator band

Photo of "septomarginal trabiculation" at acc.org

Photo with caption "moderator band" at tjc.edu

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