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Related to decussation: decussation of pyramids


 (dĕk′ə-sā′shən, dē′kə-)
1. A crossing in the shape of an X.
2. Anatomy An X-shaped crossing, especially of nerves or bands of nerve fibers, connecting corresponding parts on opposite sides of the brain or spinal cord.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(ˌdi kəˈseɪ ʃən, ˌdɛk ə-)

1. an instance of crossing or the condition of being crossed in the form of an X.
2. a nerve or tract of nerve fibers that crosses from one side of the central nervous system to the other.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


the state of being in the form of an X. See also joining.
See also: Form
-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.decussation - an intersection or crossing of two tracts in the form of the letter X
anatomical structure, bodily structure, body structure, complex body part, structure - a particular complex anatomical part of a living thing; "he has good bone structure"
chiasma opticum, optic chiasm, optic chiasma - the crossing of the optic nerves from the two eyes at the base of the brain
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.


n. decusación, cruzamiento de estructuras en forma de X;
___ of pyramids___ de las pirámides, cruzamiento de fibras nerviosas de una pirámide a otra en la médula oblongata;
optic ______ óptica, cruzamiento de las fibras del nervio óptico.
English-Spanish Medical Dictionary © Farlex 2012
References in periodicals archive ?
It has been confirmed using adult rats that unilateral damage in the cerebral hemisphere caused during the juvenile period (when corticospinal tract axons are still forming projections in a caudal direction) allows the corticofugal projection fibers that are descending from the sensorimotor area of the cerebral cortex on the undamaged side to form bilateral axonal projections at each level of the thalamus [14]; striatum [15]; superior colliculus, red nuclei, and pontine nuclei in the midbrain [16]; pyramidal decussation [17]; and spinal cord [18].
[14] reported that, at the neuropathological level, JS results from the hypoplasia and dysplasia of the cerebellar vermis and of pontine and medullary structures, and the absence of decussation of the superior cerebellar peduncles and the pyramidal tracts [24-26].
Indirect pupillary reflexes are not expected in birds because of the complete decussation at the optic chiasm.
It has a focal expression at the pyramidal decussation during critical neurodevelopmental stages.
Finally, the pontocerebellar fibers terminate in the cerebellar hemispheres, vermis, and paraflocculus.[3],[9] Based on the special anatomical structures of decussation of fibers in the pons, an infarct in the ventral pons might affect the ipsilateral nuclei, and the tracts that pass to the contralateral MCPs and those passing across from the contralateral nuclei [Figure 5].
The decussation of the pyramids, which defines the cervicomedullary junction, is estimated by drawing a vertical line across the medulla from the obex of the caudal fourth ventricle.
Other possibilities include bilateral cortical activation, or that decussation of the cranial nerves, particularly the trigeminal, may be more complex than is currently appreciated [28].
Cervicomedullary stimulation-evoked potentials, which provide a direct measurement of motoneuron excitability by eliciting a single volley in descending axons at the pyramidal decussation, are increased during MI [49].