Moderator band (heart)

The moderator band (also known as septomarginal trabecula) is a muscular band of heart tissue found in the right ventricle of the heart. It is well-marked in sheep and some other animals, and frequently extends from the base of the anterior papillary muscle to the ventricular septum.

Moderator band
Interior of right side of heart. (Septomarginal trabecula visible at bottom right, but not labeled.)
Details
Identifiers
Latin	trabecula septomarginalis
TA	A12.1.02.020
FMA	7272
Anatomical terminology

The moderator band is important because it carries part of the right bundle branch of the AV bundle of the conduction system of the heart to the anterior papillary muscle. This shortcut across the chamber of the ventricle seems to facilitate conduction time, allowing coordinated contraction of the anterior papillary muscle.

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 in his exploration of human anatomy.

The moderator band is often used by radiologists and obstetricians to more easily identify the right ventricle in prenatal ultrasound.