what is the thick layer, middle layer of the heart called?
myocardium. [mÄ«â²Åkaerâ²ÅkÃ¤rÂ·dÄ]. Ém: Etymology, gk, mys, muscle, kardia. heart a thick contractile middle layer of uniquely constructed and arranged muscle cells that forms the bulk of the heart. Wall the myocardium contains a minimum of other, tissue except blood, vessels and is covered interiorly by the. endocardium