sentence2_structure: the muscular and skeletal organs<>are known as<>the musculoskeletal system
sentence1: Meridian systems are studied, which explain the interrelationships of the various internal organs with the muscular, skeletal, nervous, circulatory, endocrine, and lymphatic systems.
sentence2: Together, the muscular and skeletal organs are known as the musculoskeletal system.
question: Together, the muscular and skeletal organs are known as what?