Specialized muscle fibers in the heart that transmit electrical impulses from the atrioventricular node (AV Node) to the Purkinje fibers are fascicles, also referred to as bundle branches. These start as a single fascicle of fibers at the AV node called the bundle of His that then splits into three bundle branches: the right fascicular branch, left anterior fascicular branch, and left posterior fascicular branch.
Human muscles are made up of hundreds of thousands of fibres which are formed in the body before birth – and they cannot be replaced. Each muscle in the body is made up of a bundle of fibres called a fascicle, surrounded by a layer of tissue.
Creating a 3D image of the trunk using a microCT scanner, the researchers traced the individual muscle parts, called fascicles, to reconstruct the thousands of microscopic muscles.