The Math of a Muscle

Many wonder, few comprehend, most claim to know.
Is it a question?
You ask,
Neither do I know the absolute answer to that,
Maybe a comment it is,
Perhaps a matter of a unified complex muscle,
Its location?
The torso!
It's denoted by a word who's character count is divisible by a value who's ratio is for “two” & is “two”
Not very easy to notice instantly!
But when found it is to be treasured and valued.
It seems to follow some trend,
Not much of permutations & combinations.
 For perfectionists it takes a linear trend relation between two bodies of relative similarities,
For theorists it conforms to exponential predictions,
But for optimists it is rather quadratic, hence worth having when understood,
 What is it?