Alright, so we're going to explain the difference between muscle spindles and Golgi tendon organs in five minutes or less. So here we go. Muscle spindles, really important guys. These are little muscle fibers within the actual contractile fibers of the muscle.
So we're actually going to show you here too. If these are the contractile fibers of the muscle, this is actin and myosin, they overlap, they shorten. Within that muscle are these hidden secret white fibers.
So these White fibers, these are our muscle spindles. They're hidden within the contractile fibers. So these are what we call intrafusal. They're within the rest of the fibers.
And they're sensory. So these are the sensory intrafusal muscle spindle fibers. So what do they do?
Great question. All right, so muscle spindles, really important, guys. Muscle spindles sense muscle stretch. So if a muscle is stretching, That's going to send a signal from the muscle spindle. So see this blue right here?
That's that sensory muscle spindle right within that muscle belly. So that's that intrafusal fiber. It's sending a signal through a nerve to the spinal cord, and then it's going to communicate back to the rest of the fibers. So we're communicating from the muscle spindle to the muscle fibers of the same muscle.
What it's going to do is it's going to sense a muscle stretch, and then it's going to tell the muscle to activate. So this is facilitating a muscle action. So we're sensing a stretch.
So for example, in a baseball pitch, if you're stretching the front of your shoulder as you're laying back into the pitch, it's going to contract the muscle. So it's going to sense that stretch and cause a muscle contraction. So that's the muscle spindle. Now we're going to go into the Golgi tendon organ.
This is a little bit different. So the Golgi tendon organ is going to be within the tendon. So we have muscle fibers and then on either side of those muscle fibers is the tendon that connects the muscle to the bone. So within that muscle or within that tendon right here is the Golgi tendon organ. We're just representing it as a black dot.
There's thousands of them within tendons, but we're just representing it as one dot there. So that Golgi tendon organ is going to sense muscle tension or muscle stretch. So it's sensing it.
if the tendon is stretching out. So really important here, guys, like if a muscle is activating a lot, the tendon is what's going to stretch. So say you're doing a max back squat and you have your one rep max on the bar and your muscle is really activating hard, that now is sensing that, that's causing the tendon to stretch, the Golgi tendon organ. what's going to sense that stretch of the tendon and it's going to try to protect the muscle. So if you're really really contracting that muscle hard it's going to tell that muscle to to turn off a little bit.
It's going to inhibit so it's going to cause muscle inhibition. It's going to tell that muscle calm down don't activate quite as much and that's going to put a little bit of a less force through the tendon, less stretch to the tendon. So just to recap guys muscle spindles sense muscle stretch So it's that intrafusal fiber. It's sensing that the muscle is stretching and it's causing a muscle contraction Golgi tendon organs are doing the opposite They're sensing that the muscle is activating really hard and they're telling the muscle to relax So they're sensing that activation and they're causing Inhibition.
Alright guys, so I hope that helps if you have any questions Go ahead and leave it in the comments If you like this video give it a thumbs up and then go ahead and hit that subscribe button. Alright, see you in the next one