Cardiac muscle (heart muscle) is involuntary striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle. These three types of muscle all form in the process of myogenesis. The cells that constitute cardiac muscle, called cardiomyocytes or myocardiocytes, contain only three nuclei. The myocardium is the muscle tissue of the heart, and forms a thick middle layer between the outer epicardium layer and the inner endocardium layer.
Riley Matthews is the main character and title character of Girl Meets World. She is the fourteen-year-old daughter of Cory and Topanga Matthews. Riley and August Matthews are Cory and Topanga's only children, of which Riley is the eldest.
Other members of the Boy Meets World cast have either recurring roles or cameo appearances. On August 6, 2014, Girl Meets World was renewed for a second season by Disney Channel. The second season premiered on May 11, 2015.