pyramidal decussation


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py·ram·i·dal de·cus·sa·tion

(pir-am'i-dăl dē'kŭs-ā'shŭn)
The intercrossing of the bundles of the pyramidal tracts at the lower border region of the medulla oblongata.
Synonym(s): decussatio pyramidum [TA] , motor decussation.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

pyramidal decussation

The crossing of 90% of the axons of the corticospinal tracts (the pyramidal tracts) in the ventral region of the caudal hindbrain. On the contralateral side, the crossed axons interdigitate with 10% of the corticospinal axons that have not crossed, and the full complement of axons continues into the spinal cord in the lateral funiculus.
Synonym: decussation of the pyramids
See also: decussation
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