Hamstring
The brachiocephalicus muscle extends the head and neck. It also pulls the front leg forward.
Adductor magnus
Most muscles in the body have "counterparts", one pulls and your leg curls up, the other pulls and the leg straightens. They would be on opposite sides of your leg. The "biceps" are the upper arm top muscle, and the tri-ceps (I think) is the upper arm bottom muscle. They work in conjunction to let you 'curl a barbell'' or do a chin-up.
Rhomboid Major
ur hamstring and iwould get it checked out if it popped
when you pull the leg it helps the saddle sit better it can also smooth out and wrincles under the girth
it hurts
Maybe the dog is fustrated
an erection
It's difficult to lose fat in targeted areas. One way to increase fat loss in your legs is to perform weight-bearing exercises. This will decrease the fat in your legs while increasing muscle. Leg lifts, squats, pushes and pulls are all good leg exercises to increase muscle and burn fat.
The muscle responds and pulls on a bone by way of a tendon. It can not react until the nerve tells it to.
muscle