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What is the evolutionary advantage of the pyramidal decussation? Anyone? -- FirstPrinciples
- Why not put the question on the Reference desk, where everyone can see it? :-) --Ardonik 10:02, Jul 19, 2004 (UTC)
Evolutionary advantage of the pyramidal decussation
(Archived from the Reference Desk)
What is the evolutionary advantage of the pyramidal decussation - indeed, neuronal decussations in general (e.g. the optic chiasm)? What pressures would cause such a system to evolve? (To me, the entire 'split-brain' system seems to be prima facie inefficient.) Can anyone enlighten me? -- FirstPrinciples 15:28, Aug 15, 2004 (UTC)
- Your question suggests that you believe efficiency is a hallmark of evolution, which of course it is not! Systems evolve by a variety of fortuitous outcomes, false starts, and contingent events, and in response to changing environments: efficiency would imply design, not evolution. - Nunh-huh 05:42, 16 Aug 2004 (UTC)
- Very simple answer. The split brain allows specialization of the hemispheres rather than simple duplication. The advantage of a "spare brain" (like a spare kidney) is less than the advantage of "2 brains" that to some extent do different things. (And yes, a complete split would be bad, and yes some symmetrical motor functions are retained). Alteripse 16:03, 15 Aug 2004 (UTC)
- However, it is possible for a person to function with damage to the corpus callosum (with various effects). There is normally considerable intercommunication between hemispheres due to their high degrees of specialization. A split brain allows complex analysis according to opposite (but synergistic) paradigms simultaneously without interference (parallel processing). In this way, a complex result incorporating both paradigms is obtained without loss of efficiency for either. --Eequor 16:41, 15 Aug 2004 (UTC)
- The decussation may be a survival trait. Crossover of motor function may ensure that a damaged part of the body is less likely to be associated with similar damage to the region of the brain controlling it, as they are on opposite sides. --Eequor 16:41, 15 Aug 2004 (UTC)
While we're on the subject, does the Corticospinal tract article describe only the human nervous system, or all mammalian ones, or some other class? It would be nice if there were a statement in that article describing its scope. -- Heron 17:29, 15 Aug 2004 (UTC)
- I'm pretty sure the Corticospinal tract article refers only to the human nervous system. In other animals, even other primates, the basic layout of the brain can be significantly different. (Side note: in my experience there are several articles out there about general anatomy that are implicitly about human anatomy. The penis wiki comes to mind, which deals with the human penis as if it is "the" exemplar of all penises in all species. We should be careful to avoid the trap of anthropocentrism.) -- FirstPrinciples 01:53, 16 Aug 2004 (UTC) -- not to mention phallocentrism! -- Alteripse 01:57, 16 Aug 2004 (UTC)
It (probably) does refer to the human spinal cord in particular. In monkeys and cats, for example, messages for fine distal muscle movements are carried by the rubrospinal tract - rather than the phylogenetically younger corticospinal tract. Chris.
Is it intentiional to omit cranial nerves IX and X (glossopharyngeal and vagus) from the Lower Motor Neurone section? It seems strange since each of these nerves carry both sensory and motor neurones. —Preceding unsigned comment added by Miniyazz (talk • contribs) 02:08, 3 December 2007 (UTC)
The pyramidal tract is a big collection of tracts and the corticospinal tract is a part of the pyramidal tract, with the corticobulbar (corticonuclear) tract and corticomesencephalic tract. This is a major mistake and needs to be corrected! Its a general misundertsanding since the major part of the pyramidal tract is the corticospinal tract (therefore often used as a general term).
- I agree. The page should be moved to "pyramidal tract" and "corticospinal tract" and "corticobulbar tract" should link to here. We are taught in medical school that pyramidal and corticospinal are NOT synonymous as indicated in this article, as you note here. Looks like this might take a bit of time to correct...maybe we should for now flag the article for inaccuracy until this can be remedied properly?--Xris0 (talk) 19:41, 10 January 2012 (UTC)
- I started cleaning up the header, but we could use an expert or someone with more anatomical experience...I also flagged the article for cleanup. Also, "pyramidal system" might be the most appropriate root page for these concepts. Anyone have input on this?--Xris0 (talk) 19:53, 10 January 2012 (UTC)
I do not feel that I can correct this entire article since Im only a medical student in process of learning about the body and its neural system.
2nd image doesn't help much. Try subtitute it with this image http://upload.wikimedia.org/wikipedia/commons/b/b2/Spinal_cord_tracts_-_English.svg — Preceding unsigned comment added by 22.214.171.124 (talk) 02:54, 6 May 2012 (UTC)
Should we have a disambiguation page?
Would it be possible to mention that the Pyramidal tracts have a "popular culture" reference in the 1985 Movie, National Lampoon's European Vacation? Its one of the questions in the game show in the opening scene? 126.96.36.199 (talk) 15:35, 12 July 2013 (UTC)Christopher Carbone 188.8.131.52 (talk) 15:35, 12 July 2013 (UTC)
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