Your to the muscles, telling them to

Your brain has many jobs, from blinking your eyes to reaching for food. The primary motor cortex is central to movement. How does this work? In this lesson, learn about your amazing brain.

Motor Regions of the Brain

You probably recognize your brain as the part of your body that allows you to think, remember and make decisions. While all those things are true, your brain also does many more things, including allowing you to look at the screen to watch this lesson. Scientists now know the brain has several parts responsible for different jobs.

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From cognitive functioning to muscle control, your brain is the center of action.Advances in technology have allowed scientists to identify different parts of the brain and what they do. They can measure and observe signals your brain sends to different parts of your body and the reactions your body has to these signals.

Signals sent to your muscles all originate in the motor cortex region. The motor cortex region is responsible for all voluntary muscle movements, like taking a drink of water or getting yourself out of bed in the morning. Scientists divide the motor region into three main parts: the primary motor cortex, the supplementary motor cortex and the premotor cortex. Let’s take a close look at the primary motor cortex.

What Is the Primary Motor Cortex?

Every voluntary movement you make is controlled through the primary motor cortex (PMC), which is located in the back of the frontal lobe, just about at the top of your head.

Signals in your brain are sent to the muscles, telling them to make a movement. For example, some time after you woke up this morning, you might have thought to yourself, ‘I need to get up.’ Without giving it a second thought, a short while later you were standing by your bed and making your next decision of the day. In that brief period of time, your PMC and other parts of your brain were doing a tremendous number of calculations to avoid having you fall in a heap on the floor.

Primary Motor Cortex in Action

Even if you groaned when the alarm went off, you actually made the conscious decision to get out of bed in your prefrontal cortex, the part of your brain responsible for making decisions.

The prefrontal cortex sends signals to the premotor cortex, the part of your brain that helps with muscle control. These signals are finally sent to the primary motor cortex, the big boy of this group, responsible for making the muscles move and work together.

The Motor Regions in Action

Imagine your brain having this conversation when you decide to get up in the morning.

The prefrontal cortex begins the process. ‘Hey, premotor cortex, wake up the primary motor cortex so we can get this body standing beside the bed.’The premotor cortex responds, ‘I’m on it.

We’ve done this set of movements before, people. Initiate ‘get-out-of-bed’ sequence.’ The premotor cortex then sends a signal to the core muscles to align properly for getting upright. That way you don’t fall over!The PMC takes the cue.

‘Got it! Getting out of bed requires seventeen major muscle groups, but we have to fire them in the correct order for this to happen. Cerebellum, start paying attention to the sensory organs so we know if we’re on target. Sensory organs, keep that information coming in!’The sensory organs chime in, ‘Gobs of information coming at you: speed, relative location, orientation, pressure, temperature …’ The PMC says, ‘Right then.

Power down major muscle groups 1-5, 12, and 16 over the next 0.1 seconds. The rest can go to 50% for the next 0.5 seconds and then maintain 10%, except for 11, who is still moving slowly today.

Pick up the pace, 11!’Sound kind of like a military sequence? Your brain is much like a command center, giving specific directions and responding quickly. Let’s see how this story ends.The major muscle groups say, ‘Got it. Bringing muscle contractions in line with recommendations.’ PMC shouts ‘And all stop.

Nice job, everyone! Stand by until further notice.’Just like a military command center, your motor region works to make you move. The primary motor cortex is at the center of the action, taking signals and moving muscles.

Lesson Summary

Let’s review. The movements you make in your body, from blinking your eyes to getting out of bed, require coordinated work between your brain and your muscles. The part of your brain responsible for these movements is called the motor region.

It is divided into three parts: the primary, supplementary and premotor cortices. When signals are sent to the primary motor cortex, it knows to move muscles in a specific way for voluntary movement. Without the primary motor cortex, your body wouldn’t even be able to lift a finger.

Learning Outcomes

After this lesson, you’ll have the ability to:

  • Describe the motor regions in the brain and their functions
  • Explain the purpose of the primary motor cortex
  • Summarize how the primary motor cortex works in conjunction with the other motor regions
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