Pyramid

Brain: Pyramid (brainstem)
Medulla oblongata and pons. Anterior surface. (Pyramid visible at center.)
Section of the medulla oblongata at about the middle of the olive. (Pyramid visible at bottom center.)
Latin	pyramis medullae oblongatae
Gray's	subject #187 768
NeuroNames	hier-702

The ventral portion of the medulla oblongata contains medullary pyramids. These two structures travel along the length of the medulla oblongata and are bordered medially by the anterior median fissure. They each have an anterolateral sulci along their lateral borders.

The medullary pyramids contain motor fibers that are known as the corticobulbar and corticospinal tracts. Extrapyramidal tracts are those motor tracts that do not traverse the medullary pyramids.

The medullary pyramids seem to disappear as they travel toward the spinal cord. This occurs as a result of decussation. The medullary pyramids taper into the anterior funiculus of the medulla spinalis, with which they appear to be directly continuous.

See also

• Corticospinal tract
• Decussation of the pyramids

Additional images

• 

  The formatio reticularis of the medulla oblongata, shown by a transverse section passing through the middle of the olive.

• 

  Dissection showing the projection fibers of the cerebellum.

• 

  Human brainstem anterior view

External links

• Diagram at csus.edu

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

This neuroscience article is a stub. You can help Wikipedia by expanding it. v t e