The Gluteus Maximus, one of three gluteal muscles, is located at the back of the hip and is commonly called the buttocks. It’s main functions are hip extension and hip external rotation. Some great exercises to train the Gluteus Maximus muscles include squats, deadlifts and lunges.
The Sartorius are long thin muscles that run from the outside of the upper thigh down and across the leg to the inside of the knee. Its main functions are hip flexion, abduction and knee flexion. Some great exercises to train the Sartorius muscles include squats, cable abduction and step ups.
The Stapedius, is a tiny muscle less than 2 millimeters long, located in the middle ear. Its function is to control the movement or vibration of the smallest bone in the body, the stapes or stirrup bone. Sorry, I don’t know specific exercises to train the Stapedius muscles, but I’m guessing loud music might do the trick.
While the others above are well documented, this one is a bit harder to define. Since there are different types of strength, such as absolute strength, dynamic strength and strength endurance, there are a few candidates for top spot here.
If we are talking about absolute strength, meaning the ability to generate maximum force, then the winner is the Masseter, located in the jaw. It’s main function is mastication or chewing. Again I’m not sure of any specific exercises that help train the Massester muscles, but I’m sure chewing or biting really hard should do the trick.