all right as your so in this video we're gonna continue the series on the descending track so if you guys haven't already seen it go watch the vestibular spinal and the pond to a particular spinal and this video we're gonna talk about the rubra spinal tract so the rube ros spinal tract starts where well it's kind of a tricky little system here it starts generally within the red nucleus you know here you have midbrain pons medulla right and then you have the spinal cord sections here and then here's your cerebral cortex in here cerebellum when in the midbrain you have these special nuclei here they're called the red nuclei all right so this is your red nucleus we mentioned it a little bit in the vestibular spinal tract but again here is your red nucleus and again they're located within the midbrain now we have to know these red nuclei what is their overall function with respect to what are they doing what kind of muscles are they activating well it's gonna be a lot easier to remember these guys now because we've already said that those are the extensor muscles so what do you think these two are going to be these last two here are gonna be flexor muscles so the rubra spinal tract is primarily associated with stimulating what kind of muscles what kind of muscles would you expect these to be these are gonna be your flexor muscles now there's a little bit of contradicting evidence out there they say that the rubra spinal tract when we talk about flexor muscles they say it more specifically supplies the upper limb flexors okay so they believe that it supplies more of the upper limb flexors but they say that there's been a lot of research that the rubra spinal tract keeps the distal all right the lower limb flexors in check through the mechanism that's not completely well known but they do know that it's stimulating your flexor muscles primarily those of the upper limb flexors so now we know it supplies the flexor muscles we know that this tract technically starts within the red nucleus why I was saying technically is you know there's got to be stimuli there's got to be something that stimulates these nuclei what is it you know the cerebral cortex cerebral cortex you have a bunch of different types of cell bodies up here primarily those from the primary motor cortex the premotor cortex the Supplemental motor area we've talked about this in the corticospinal tracts well guess what these guys can have some fibers that can give stimulation to the red nucleus right it's the same thing over here if I had a couple of these guys over here here's some cell bodies from the cerebral cortex from the primary motor cortex premotor supplementary motor all of these guys can come over here and supply the red nucleus so they call these cortical rube rule fibers so what are these fibers here called these ones they're called quartic oh rube rule fibers because they're actually going to be going from the cortex to the red nucleus okay so from the cortex to the red nucleus we're gonna have these cortical rubra fibers why don't I tell you this okay so from here you know the descending fibers this is basically gonna form because it's gonna continue they just give off little collaterals this is going to continue as the cortical spinal tract right but what happens is the red nucleus is gonna have what's called the rubra spinal tract which assists the actual corticospinal tract now there's something else that has to be stimulated by you know um in the cerebellum and has some special nuclei and these special nuclei you have here they're called deep cerebellar nuclei we'll have a video on the cerebellum in the future but this there's special nucleus they're called globos you have what's called the globos nucleus and you have another one called the Ambala form Ambala form nucleus okay so we have the Ambala form nucleus and then what else do we have we have the globos nucleus so imagine these are these guys right here so here's your globos nucleus and here's maybe in Ambala form nucleus same thing you'd have it over here as well now what can these globos nucleus and the Ambala form nucleus do what they'll do is is remember what's the cerebellum good on it's good at being able to understand what's going on with proprioception remember that we're gonna have fibers coming into the cerebellum - no let it know of what's going on with proprioceptors right which is basically understanding the position of our joints our ligaments or tendons and muscles within three-dimensional space I know where my arm is right where exactly it's touching my nose that kind of thing the cerebellum is constantly being alerted of unconsciously right now the cerebellum knows that and he says okay read nucleus so you got the a okay from the quartic Oh rubber fibers from the cortex but let me give you a little bit even more of a modification I'm going to send some information to you from the actual cerebellum via the globos nucleus and the Ambala form nucleus now once they come out and tell the red nucleus this the red nucleus has got pretty much everything it needs to start sending the fibers down so now from here it does something really interesting you know the red nucleus it crosses in the midbrain it crosses in the midbrain they call it the ventral tegmental decussation not necessarily super important but again it's important to know that it's crossing it's good the fibers are gonna go to the contralateral side it's important to know where they're crossing they're crossing in the midbrain they call it the ventral tegmental decussation now as these fibers are going down alright so here's your rubra spinal tract the rubra spinal tract is going to go where so this is a rubra spinal tract now what its gonna do is it's going to enter into the the lab or white column because you know that's where most of the fibers of the cortical spinal tract the lateral corticospinal tract we said 80% of the fibers cross and go into the lateral white column remember I told you the rubra spinal tract is trying to help in this process trying to assist the corticospinal tracts so it goes down here in we're very close to where the actual lateral corticospinal tract a besom might even get intermixed now what does it do from here it's actually going to give extenuation it's going to give stimulation to these different types of alpha and gamma motor neurons that are going to be located within the anterior or intro gray horn now these alpha motor neurons and what else we also said that there's going to be gamma motor neurons they can go out to different skeletal muscles and from here what type of skeletal muscles did we say it's going to we said it's going to the flexor muscles primarily of the upper limbs okay so now we know what's going to the upper limbs let's assume that it goes down a little bit farther though just for simplicity sake here we're gonna keep having it coming down and then as it comes down it gives off another little collateral here comes down here gives off another little collateral right here on to what alpha and gamma motor neurons in let's just say that this isn't this is a cervical part of the spinal cord and this is a little lower maybe even the upper thoracic vertebrae right and these are going to go up to different skeletal muscles that are important with being able to regulate limb flexion specifically for the upper limbs okay and again what is this out what is this motor neuron this is an alpha the blue one and the green one is a gamma motor neuron why are these important the gammas for the muscle spindles to keep those suckers taut and then the Alpha is to cause the extra fuse of muscle fibers to contract shortening and lengthening the muscle fibers so now a rubra spinal tract is really important for what what's the overall goal here overall goal is to stimulate the flexor muscles what type of flexor muscles the upper limb but don't forget recent research has supported that the rubra spinal tract keeps the lower limb flexor muscles intact and in check alright what are the stimuli for this tract one could be from these cerebellum the deep cerebellar nuclei via the globos and Ambala form nucleus and it can also get collaterals from the corticospinal tracts via the cortical rubra fibers then it decussate s-- in the midbrain we have the ventral tegmental decussation and descends downwards and as it descends downward what does this track here called again just for the sake of it Roah spinal attract as it goes down and moves into the latter like columns some even books say that inter mixes with the lateral corticospinal tract gives off collaterals to the anterior venture great horn which go to the flexor muscles of the upper limb and keep the actual lower limb flexor muscles intact or in check so that should make sense alright guys so that pretty much covers the rubra spinal tract so now that we covered this one in the next video we're gonna talk about the medullary reticulospinal tract and go into that one in detail again alright and then after this one we'll have a nice little overview of everything to just make sure that we hit it home with this whole concept alright hope to see you guys there [Music] you [Music]