The purkinje fibres are found in the sub-endocardium.

They are larger than cardiac muscle cells, but have fewer myofibrils, lots of glycogen and mitochondria, and no T-tubules. These cells are connected together by desmosomes and gap junctions, but not by intercalated discs.

They are specialised conducting fibres, which extend from the interventricular septum, to the papillary muscles, and up the lateral walls of the ventricles. More on contraction of the heart