The primary motor cortex (Brodmann area 4) lies in the precentral gyrus and paracentral lobule and is the main source of commands for voluntary movement. It is arranged as a motor homunculus, with the leg on the medial surface and the hand and face on the lateral surface; the hand, lips and tongue have large areas because they need fine control. It contains giant Betz cells.
| Location | Precentral gyrus on the lateral surface and anterior paracentral lobule on the medial surface of the frontal lobe |
|---|---|
| Parts |
|
| Connections | |
| Blood Supply | Middle cerebral artery; Anterior cerebral artery (leg area) |
Generates the signals that control the force and direction of voluntary movement on the opposite side, especially fine movements of the hand and face.
Damage causes an upper motor neuron pattern of weakness on the opposite side, with increased tone, brisk reflexes and an upgoing plantar response developing over time. In amyotrophic lateral sclerosis, motor cortex neurons degenerate along with lower motor neurons. It is the target of mapping during surgery and of transcranial magnetic stimulation in rehabilitation research.
Weakness of one side of the body after damage to the opposite motor cortex or its descending fibres.
Progressive degeneration of upper and lower motor neurons causing weakness, spasticity and wasting.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
