Background
I've noticed that my front squats are seriously lagging behind. I know that most people have a weaker front squat than back squat, but mine is about 50-60% behind in terms of 5-8RM.
I suspect that among all the muscle groups that are worked by both variations, there is a subset of muscles that are holding me back.
Question
Which muscle groups are more central to the front squat than the back squat? What accessory exercises would assist me in developing a stronger front squat?
How I do them
In terms of stance, I have a semi-wide stance, feet pointing only slightly outward. Akin to riding a horse.
I cross my arms over the bar, rather than the backward wrist bend. I find I have no problem keeping the bar on my shoulders as I raise my elbows in front so that they are always parallel to the ground.
I place the bar just inside the front delt, so the bar is very close to my neck, and since the front delt is flexed by raising the elbow, the bar has additional support which prevents it from going anywhere.