medulla oblongata | Description, Anatomy, & Function

medulla oblongata, also called medulla, the lowest part of the brain and the lowest portion of the brainstem. The medulla oblongata is connected by the pons ... medullaoblongata TableofContents medullaoblongata Introduction FastFacts RelatedContent Media Images More MoreArticlesOnThisTopic Contributors ArticleHistory Home Health&Medicine Anatomy&Physiology medullaoblongata anatomy Actions Cite verifiedCite Whileeveryefforthasbeenmadetofollowcitationstylerules,theremaybesomediscrepancies. Pleaserefertotheappropriatestylemanualorothersourcesifyouhaveanyquestions. SelectCitationStyle MLA APA ChicagoManualofStyle CopyCitation Share Share Sharetosocialmedia Facebook Twitter URL https://www.britannica.com/science/medulla-oblongata GiveFeedback ExternalWebsites Feedback Corrections?Updates?Omissions?Letusknowifyouhavesuggestionstoimprovethisarticle(requireslogin). 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ExternalWebsites MedicineLibreTextsLibrary-MedullaOblongata By TheEditorsofEncyclopaediaBritannica • EditHistory TableofContents cerebellum;humanbrain Seeallmedia RelatedTopics: solitarytractnucleus olive cochlearnucleus ventralcochlearnucleus trapezoidbody ...(Showmore) Seeallrelatedcontent→ medullaoblongata,alsocalledmedulla,thelowestpartofthebrainandthelowestportionofthebrainstem.Themedullaoblongataisconnectedbytheponstothemidbrainandiscontinuousposteriorlywiththespinalcord,withwhichitmergesattheopening(foramenmagnum)atthebaseoftheskull.Themedullaoblongataplaysacriticalroleintransmittingsignalsbetweenthespinalcordandthehigherpartsofthebrainandincontrollingautonomicactivities,suchasheartbeatandrespiration.Themedullaisdividedintotwomainparts:theventralmedulla(thefrontalportion)andthedorsalmedulla(therearportion;alsoknownasthetegmentum).Theventralmedullacontainsapairoftriangularstructurescalledpyramids,withinwhichliethepyramidaltracts.Thepyramidaltractsaremadeupofthecorticospinaltract(runningfromthecerebralcortextothespinalcord)andthecorticobulbartract(runningfromthemotorcortexofthefrontallobetothecranialnervesinthebrainstem).Intheirdescentthroughthelowerportionofthemedulla(immediatelyabovethejunctionwiththespinalcord),thevastmajority(80to90percent)ofcorticospinaltractscross,formingthepointknownasthedecussationofthepyramids.Theventralmedullaalsohousesanothersetofpairedstructures,theolivarybodies,whicharelocatedlaterallyonthepyramids.leftcerebralhemisphereofthehumanbrainMedialviewofthelefthemisphereofthehumanbrain.EncyclopædiaBritannica,Inc. BritannicaQuiz HumanBody:FactorFiction? Howdeepisyourbodyofknowledgeabouttheinnerworkingsofhumans?Testitwiththisquiz. Theupperportionofthedorsalmedullaformsthelowerregionofthefourthventricle(afluid-filledcavityformedbytheexpansionofthecentralcanalofthespinalcorduponenteringthebrain).Similartothespinalcord,thefourthventricleissurroundedbywhitematterontheoutside,withthegraymatterontheinside.Thedorsalmedullaalsoisthesiteoforiginforthelastsevencranialnerves,mostofwhichexitthemedullaventrally.Themedullaconsistsofbothmyelinated(whitematter)andunmyelinated(graymatter)nervefibres,and,similartootherstructuresinthebrainstem,thewhitematterofthemedulla,ratherthanlyingbeneaththegraymatter,isintermingledwiththelatter,givingrisetopartofthereticularformation(anetworkofinterconnectedneuronclusterswithinthebrainstem).Neuronsofthereticularformationplayacentralroleinthetransmissionofmotorandsensoryimpulses.Thoseinthemedullacarryoutcomplexintegrativefunctions;forexample,differentfunctionalcentresspecializeinthecontrolofautonomicnervousactivity,regulatingrespiration,heartrate,anddigestiveprocesses.Otheractivitiesofneuronsinthemedullaincludecontrolofmovement,relayofsomaticsensoryinformationfrominternalorgans,andcontrolofarousalandsleep.Injuriesordiseasesaffectingthemiddleportionofthemedullamayresultinmedialmedullarysyndrome,whichischaracterizedbypartialparalysisoftheoppositesideofthebody,lossofthesensesoftouchandposition,orpartialparalysisofthetongue.Injuriesordiseaseofthelateralmedullamaycauselateralmedullarysyndrome,whichisassociatedwithalossofpainandtemperaturesensations,lossofthegagreflex,difficultyinswallowing,vertigo,vomiting,orlossofcoordination.TheEditorsofEncyclopaediaBritannicaThisarticlewasmostrecentlyrevisedandupdatedbyKaraRogers.