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Anatomy of Brain Stem.pptx - Anatomy of Brain Stem ANA 313...

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Anatomy of Brain StemANA 313Neuro-anatomy Lecture
Introduction to brainstemCompositionMedulla oblongataPonsMidbrainoccupies the posterior cranial fossa of the skull.connects the narrow spinal cord with theexpanded forebrain.Function of Brainstem(1)Serves as a conduit for the ascendingtracts and descending tracts connectingthe spinal cord to the different parts ofthe higher centers in the forebrain(2)Contains important reflex centersassociated with the control of respirationand the cardiovascular system and with thecontrol of consciousness(3)Contains the important nuclei of cranialnerves III through XII.
Medulla Oblongata:GrossappearanceConnects the pons to spinal cordAbout 2.5 cm in lengthIt is conical in shapeUpper half surrounds the cavity offourth ventricleLower half surrounds the centralcanal
Anterior View of the Medulla oblongata:Gross Cont.Anterior median fissurePyramid» Cortico-spinal fibresDecussation of pyramidsExternal Arcuate fibresAbove the decussationPass laterally tocerebellumThe olives→inferior olivary Nu.Posterolateral to the pyramidsInferior Cerebellar peduncleConnects Medulla tocerebellum
Nerves that emerges from its surfaceHypoglossal– groove b/t olive andpyramidGlossopharyngeal, Vagus andAccessory (Cranial root)– Groovebetween the olive and InferiorCerebellar peduncleA- Anterior View of the Medulla OblongataMedulla Oblongata:Gross appearance cont.
Posterior Surface of the Medulla oblongataSuperior surface – lower part of thefloor of the 4thVentricleFeatures:Posterior Median SulcusGracile tubercle– NucleusgracilisCuneate tubercle– NucleusCuneatus
The internal structure of the medulla oblongataConsidered at four levels:1)level of decussation of pyramids – A2)level of decussation of lemnisci – B3)level of the olives4)level just inferior to the pons.
Medulla at thelevel of decussation of pyramidsA transverse section throughthe inferior half of themedulla oblongatathrough the decussation of thepyramids, the great motordecussation.It contain the following nuclei:Nucleus gracilis, nucleuscuneatus, spinal nucleus ofcranial nerve V, accessorynucleus
Medulla at thelevel of decussation of lemnisciTransverse section just above thelevel of the decussation of thepyramidspasses through the decussation oflemnisci -the great sensorydecussationthis decussation takes place anteriorto the central gray matter andposterior to the pyramids.It contain the following nuclei:Nucleus gracilis, nucleus cuneatus,spinal nucleus of cranial nerve V,accessory nucleus, hypoglossalnucleus
Medulla at thelevel of the olivesA transverse section through theolives passes across the inferior partof the fourth ventricleThe amount of gray matter hasincreased at this level owing to thepresence of the many nucleiIt contain the following nuclei:Inferior olivary nu., spinal nucleus ofcranial nerve V, vestibular nu.,glossopharyngeal nu., vagal nu.,hypoglossal nu., nucleus ambiguus,nucleus of tractus solitarius

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Term
Spring
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Tags
Neuroanatomy, Medulla oblongata

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