The answer to this Q Is not that simple as there are different muscle types (3 actually) and each individual person has a variation with there own body There are seven that contend for the strongest..
1.External muscle of the eye...Up to 10-15,000 movements an hour When watching a tennis match even more..
2.Gluteus Maximus...This is the largest muscle in the body,it holds us upright
3.Heart..This is the hardest working muscle in the body an estimated 3 billion heart beats in a lifetime and think its all for love..
4.Masseter...The strongest muscle based on weight ratio This muscle helps the jaw chew up your food it can create a force as greta as 200 Kg on region of the teeth
5.Muscle region of the Uterus... This is responsible for giving birth, pushing the baby with contractional cycles that are controlled by the pituary gland in the brain
6.Soleus...Found just below the gastrocnemius (your calf muscle) this muscle can pull with the greatest force and is used in running, dancing, walking etc. This muscle stops you from falling backwards..
7.Tongue..The muscles in the tongue never stop working 24/7 They have a complex job of sorting all types of tasks Cleaning your tongue with a toothbrush is recommended A healthy tongue is red in color..
There you have it the body wonderful..