 So as you may know, a tract is a bundle of axons. In this video we'll be talking about three tracts that are involved in the transmission of subconscious motor signals. This being our brain, this our brainstem and the spinal cord. We're going to remove the midbrain, pons and medulla so we can see the vestibular nuclei here. A nucleus is a discrete chunk of gray matter and gray matter is the cell bodies of neurons. These cell bodies receive information from neurons that are coming from the inner ear. They're transmitting info about the head's position in space from the semicircular canals through the vestibular nerve. Having dropped that info here, this neuron's axon heads down in a tract known as the vestibulospinal tract. Descending just posterior to the pyramids of the medulla, the axon then fires on the cell body of a lower motor neuron in the anterior horn of the spinal cord's gray matter. So that's the vestibulospinal tract. It receives info about the head's position and conveys it to muscles of the head and upper limbs which can adjust our positioning if required. The reticulospinal tract is up next for which we will bring this in, the reticular formation. Reticular formation is composed of many nuclei and spans the medulla to the midbrain. So with their cell bodies in here, our axons then descend in a collection known as the reticulospinal tract. They drop their information on cell bodies again in the anterior horn of neurons which head out to muscles in the torso and upper limb. The purpose of these messages are to maintain our posture, especially while we're in motion. The tectospinal tract begins in the tectum which is this part of the midbrain. So within the tectum we have these little mounds of gray matter called colliculi, Latin for mount, and we have superior colliculi and inferior colliculi. The superior colliculi receives visual info, the inferior auditory. If we see bright sudden movement or hear loud sudden noises, this information is passed down the tectospinal tract to activate muscles of the head, neck, and upper limbs. So any sudden movement in response to something you weren't expecting to see or hear, that's the work of the tectospinal tract. So the tracks that we've talked about have a few things in common. They all transmit subconscious motor information and they all move down through the medulla behind or posterior to the medullary pyramids and that is of course why they're known as the extra pyramidal tracks. All right so I hope you've enjoyed that. If you have hit subscribe and we will see you next time.