The trabeculae carneae of the heart are a number of projections of the contractile myocyte - myocardial - layer of the ventricles. They are covered by endocardium. They may present in a number of forms:

• surface elevations with grooves between them
• ridges, fixed at both ends to either the ventricular wall or septum, but the intermediate section of muscle is freely mobile within the cavity
• papillary muscles