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py·ram·i·dal de·cus·sa·tion(pir-am'i-dăl dē'kŭs-ā'shŭn)
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