肌肉神经支配

so there are muscles that we control and then there are muscles that control us so in this video we're gonna be talking about voluntary versus involuntary muscle control and then I'll talk about the autonomic versus the somatic nervous systems and we'll jump into a few of the subunits of those systems as well alright so imagine if we had this gentleman right here who does not look very impressed we can talk about what parts of our nervous system are responsible for voluntary control of muscles versus those parts of the nervous system that are responsible for involuntary muscle control now the first question that should come to your mind is why do we have this sort of a setup why is it important to have things that are involuntarily contracting well think about structures in our body that we don't actively think about we have the heart so we've got things like cardiac muscle we've also got things like our intestines so that's composed of smooth muscle smooth muscles also found lining our vessels whenever we need to vasoconstrict or narrow those vessels so there's also that smooth muscle there so we don't think about whether we need to divert blood away from our skin towards our abdomen or towards our brain our body just does that for us and that's muscle that's controlled on an involuntary basis what about on the flip side over here for voluntary control which of the three types of muscle do you think is under voluntary control well if you said skeletal muscle striated a skeletal muscle you'd be absolutely correct so that's how we split that up now what parts of our nervous system here do we use for voluntary versus involuntary control I'll start on this side so we have drawn here and this person who's not very impressed is the brain as it goes down into the spinal cord this general area is referred to as the cortex the cerebral cortex and that's part of voluntary control of muscle in addition to that we've also got what I can call the cord over year the spinal cord and that'll also be contributing to voluntary control of muscles and the way I'd like to remember this is that if it's something that's controlled by me if I am the one that controls the muscle function that I'm going to use either my cortex which also happens to start with a C or my cord which happens to start with a C so if it's controlled by me or if it's voluntary that's gonna be the cortex or the spinal cord that comes in handy now what about if we're talking about involuntary control this part that I'm gonna draw sort of briefly that sits kind of back here behind the spinal cord and then kind of goes in there that guy is called the brainstem the brainstem and so the brainstem is responsible for things like if we should have more blood go to our abdomen instead of our skin so if we should dilate smooth muscle in our arterioles or if our heart should beat faster the brain stem will regulate that through parasympathetic or sympathetic mechanisms we'll talk about in a minute in addition to the brainstem there's a structure that's found down here that contributes to involuntary control but it's not in the spinal cord it's actually beside the spinal cord and it's lined like a chain so I'll draw it like this with these sort of cell bodies this neuronal tissue with cell bodies that sit outside of our central nervous system in a chain and so this is called sympathetic ganglia sympathetic ganglia whoa what the heck are ganglia that sounds like it's plural for something well let's define that sympathetic ganglia or just a ganglion if we're gonna use it in a singular term a ganglion is just a cell body or a soma of a neuron that sits outside the brain and spinal cord I'll just write brain right here outside the brain and spinal cord and most of these games sit beside the spinal cord so that's an important point the sympathetic ganglia that sit beside the spinal cord and so that comes with another trick that I'd like to think about when I'm trying to remember which parts of my nervous system is responsible for involuntary control this is stuff that's going on that's beyond me it's beyond my control and so if it's beyond me I'm gonna have to use either the brain stem or neuronal tissue that sits beside the spinal cord in order to be able to cause involuntary contraction of muscle so great that's voluntary versus involuntary control