intercalated disc

noun

in·​ter·​ca·​lat·​ed disc

variants or intercalated disk

in-ˈtər-kə-ˌlāt-əd- 

: any of the specialized regions of the sarcolemma and underlying cytoplasm of cardiac muscle cells that comprise the longitudinal and end-to-end junctions between adjacent cells and that function to connect them mechanically and electrically