How muscles behave like snitches

        Did you know that the human body has snitches? Yep, that's right snitches. 

    Ever seen the Departed? .... you haven't? Have you been living under a rock? First of all, go watch the movie because this post is littered with movie references. The plot is centered around an undercover cop played by Leonardo Dicaprio getting into the Irish mob while Matt Damon plays a dirty cop that works for the mob. If that doesn't entice you the movie is littered with over-the-top Boston accents and Bostonian banter. 

     Within the body you have deeply undercover snitches within muscle tissue that rat on you. Proprioceptors or the snitch in this metaphor are specialized sensory receptors that relay information about muscles and tendons directly to the brain. Intertwined with myosin and actin lie Muscle Spindles.

Muscle Spindles aka the snitch

    Within the picture the yellow rope looking things (In real life they are white....yellow stands out more) are your Muscle Spindles. They are intrafusal (Intra-meaning inside) fibers that sense muscle stretch, muscle length and rate of change. They take that information and send it directly to the brain via alpha motor neurons. As you lift weights these Spindles are stretched allowing that muscle to activate. The heavier the weight the more the spindle is stretched allowing you to lift heavier and heavier weight. Indirectly when you lift weights you are activating that spindle. You know when you're at the doctor and the doctor tests your reflex's by taking the rubber hammer against your knee? What they are doing is attempting to activate the muscle spindles that enable your leg to kick to test your stretch reflex. A sports application is a baseball pitcher winding up (stretching the spindle) to activate muscles in the shoulder. 

    Another snitch I mean proprioceptor are your Golgi Tendon Organs (GTO's).

   

    Located within Tendons Golgi Tendons that sense muscle tension. Ever lifted weights and it's a weight that is too heavy for you. Thats your GTO sending signals via the Alpha Motor neuron to shut down muscle activity. The "shut down" of muscles is used to protect the muscle from too much resistance. While Muscle spindles activate muscles GTO's block too much muscle tension. This is similar to that one parent that allows their kid to eat candy before dinner while the other parents say no.   The principle of overload is the motor cortex to override the GTO's in order to lift the weight.