Nerve to the other side, to a muscle on the other In the head or the neck and let me actually draw the same kind of thing on the other side, sending lower motor neuron axons through the same cranial So let me just draw one lower motor neuron over here on the left side and it's going to send anĪxon through a cranial nerve to a skeletal muscle For the most part things getĪ little more complicated for the lower motor The other side of the body, so that the right side of the brain controls the left side of the body in terms of controlling Hemisphere on this side or on the brain stem on this side, we usually see weakness on Of the corticospinal tract on the other side of the brain, either up here in the cerebral Side of the spinal cord, what we see is that if there's dysfunction of these axons of the corticospinal tract on one side of the spinal cord, we usually get weakness of muscles on that same side. Now because most of the axons that make up the corticospinal tract travel down one side of the brain and then cross over to travel down the other And a tract is a collection of axons traveling together through So it's going from cerebralĬortex to spinal cord, so we call it the corticospinal tract. In the cerebral cortex, and then spinal, which means that itĮnds in the spinal cord. That are upper motor neurons, traveling from the cerebral cortex to lower motor neurons in the spinal cord, we call this the corticospinal tract. So this pathway, this collection of axons Meets the spinal cord, at the bottom of the medulla, most of these axons are going to cross over to the other side, and then they're going to travel down the other side of the spinal cord until they reach this lower motor neuron to synapse on it and control it. Through the mid brain, then the pons, then the medulla, and then at this point, where the brain stem White matter of the cerebrum and then it's going to travel down through the brain stem This lower motor neuron is going to start somewhere way up in the cerebral cortex here, in that layer of gray matter, on the outside of the cerebrum, and its axon is going to kind of travel down to the deep The upper motor neuron that's going to control That it's going to control, some of the skeletal muscleĬells in that muscle. That it branches into until it synapses in some muscle Out through spinal nerves and the smaller branches Neuron will have its soma inside the spinal cord and then it'll send it's axon But first let's think aboutĪ lower motor neuron here in the higher part of the spinal cord, on the left side. Here is the brain stem, and behind it is the cerebellum, and then beneath it is the spinal cord. So let's take the brainĪnd the spinal cord here, and I've got a little So first let's look at these longer upper motor neurons that send axons all the wayĭown into the spinal cord. Synapse on lower motor neurons or if they go a shorterĭistance to the brain stem to synapse on lower motor neurons. The upper motor neurons into some different pathways or tracts, depending on if they go all the way down into the spinal cord to Skeletal muscle cells to determine when they'll contract. The lower motor neurons to actually reach the Lower motor neuron somas and then out the axons of And so information flows from up here mainly in the cerebral cortex down these axons to the The cerebral cortex, way up here in the brain on that outside surface of the cerebrum, and their axons descend down to synapse on lower motor neurons in the brain stem or in the spinal cord. The somas of the upper motor neurons are found mainly up in The lower motor neurons and controlling their activity. But now we're going to talk about the upper motor neurons, because it turns out that while the lower motor neurons are controlling the skeletal muscle cells and telling them when to contract, upper motor neurons are the ones that are controlling Pass through cranial nerves primarily control the skeletal muscles of the head and the neck. Of the limbs and the trunk, and lower motor neurons that The lower motor neurons that pass through spinal nerves primarily control muscles Muscle cells when to contract and we talked about that Skeletal muscle cells to tell those skeletal Or in the spinal cord, and how they send axons out through nerves in the peripheral nervous system to synapse on and control The lower motor neurons, we talked about how they have their somas, either in the brain stem So upper motor neurons, which are different than the motor neurons we talked about before, which are the lower motor neurons. In this video I'm going to talk about upper motor neurons.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |