Dr. Andy Galpin

you have hundreds of thousands of muscle fibers.

Think of this like a ponytail.

So while you'd call that ponytail one thing, it's actually just comprised of thousands of different individual hairs.

So when we want to talk about the individual hair, we say hair follicle.

We want to talk about the ponytail as a unit, we say the ponytail.

So the same thing would happen.

I could talk about your hamstring muscles, but really, am I talking about one muscle, say the semimembranosus or semitendinosus, the hamstrings as a group, or the individual fibers within each of those individual muscles?

So drilling down on that, if you can imagine going back to the ponytail, there is a layer of connective tissue or fascia that surrounds each of these muscle fibers.

That holds them together, but that's what actually collectively makes them one unit and why we call that a muscle.

That muscle is then wrapped around further with more connective tissue.

All that comes together to form a tendon.

That tendon then connects to the bone such that when you activate or contract any of those muscle fibers, it contracts the muscle as a whole.

tends to contract the entire muscle group.

That entire muscle group comes together, goes into a tendon.

That tendon then pulls the bone.

So the easy example, again, sticking with the quads is an easy theme.

You contract any of the muscle fibers within, say, the vastus lateralis, the muscle that is on the far outside of your leg.

That is one of the quadricep muscles.

The entire quad tends to feel like it's contracting.

That then goes over through the patella tendon.