Cardiac Muscle.
Cardiac muscles
The muscles used to produce a heartbeat are called the "heart."
heart
Ewer
A maker of a sail
geyser, mudpot or mud pot, fumarole
Hairdresser or coifeurr.
Heart muscles are involuntary.
The heart IS a muscle. If you're talking about skeletal muscles, then they are not all at the top of your heart (because what about your abdominal muscles, thigh muscles, calf muscles, etc?)
The Cardiac muscles are found in your heart.
heart muscles
The inflammation of the heart muscles. (Cardio = heart; myo = muscles; -itis = inflammation)