The anatomy and blood supply of the papillary muscles of the left ventricle

The supply of blood to the papillary muscles is segmental in distribution, and reaches the muscle from large penetrating branches originating from epicardial vessels located radially outward from the muscle. The tip, mid-portion, and base generally receive their vascular supply from separate tributaries which have a radial arrangement. Fibrosis of the papillary muscles is most often associated with occlusive disease of the large coronary vessels. The vascular alteration accompanying this fibrosis is of two types: (1) a fine overgrowth of Class A vessels, without interruption of the Class B vessels, and (2) an interruption of all channels, with enlargement of subendocardial vessels, suggesting the utilization of these vessels in the formation of collaterals past the occluded area.