1.You heart
2-a millon: all the others I'd say!
nothing
Quadriceps (thighs), Triceps (back of your arm) and abs (stomach muscles) are the three most important muscles involved in swimming, however a well rounded, athletic body in all areas is the best.
The heart is the most important muscle because it has to pump blood constantly thru out the body
The heart is a muscle and in fact the most important
The most important flight muscles are the pectorals, which correspond to the muscles of your chest :)
Well, I don't know about you, but I would consider the heart, the lungs, which to be honest I'm not sure if they're organs or not, and the thigh muscles.
skeletal muscles
skeletal muscles
Of course.
All of the muscles are important. Without your forearm muscles you can't move your fingers, without the bicep or tricep muscles you cant bend your elbow. and it goes on for every muscle in the body.
Most of the muscles of the body are exercised when running. Of course the foot and leg muscles are needed the most but the muscles of the torso and upper body are used as well.
The hip joint is one of the most important joints in our body because it bears the body weight and the force of the strong muscles of the hip and the legs thereby stabilizing the body.
Abs are there to support your body. They also help you breath. Your abs are the most important muscles on your body. With out them you would not be able to walk sit or stand.