The pyramids are two long ridges on the front of the medulla, on either side of the anterior median fissure. They contain the corticospinal fibres on their way from the motor cortex to the spinal cord. At the lower end of the medulla about 85-90 percent of these fibres cross to the opposite side in the pyramidal decussation.
| Location | Anterior surface of the medulla oblongata, medial to the olives, between the pons and the upper cervical spinal cord |
|---|---|
| Parts |
|
| Connections |
|
| Blood Supply | Anterior spinal artery; Paramedian branches of the vertebral arteries |
Carries voluntary motor commands from the cerebral cortex to the spinal cord and is the site where most of these fibres cross to the opposite side.
A lesion of one pyramid above the decussation causes contralateral weakness, while damage below it causes ipsilateral weakness. Medial medullary syndrome affects the pyramid, medial lemniscus and hypoglossal fibres. Because arm fibres cross slightly higher than leg fibres, rare lesions at the decussation can cause cruciate paralysis with one arm and the opposite leg weak.
Infarction of the pyramid and adjacent structures causing contralateral hemiplegia sparing the face and ipsilateral tongue weakness.
Weakness of one arm and the opposite leg from a lesion at the pyramidal decussation, often from craniovertebral junction trauma.
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.
