Where nerves emerge to upper limbs 2 lumbar

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where nerves emerge to upper limbs2.Lumbar enlargementcord thickeningwhere nerves to pelvic region and lowerlimbsMedullary cone -cord tapers to a point inferiorto lumbar enlargementCauda equina -bundle of nerve roots that occupythe vertebral canal from L2S5innervates pelvic organs, lower limbsFilum terminale -becomes a component of thecoccygeal ligament
Spinal MeningesFibrous membranes that enclose the brain and spinal cordSeparate soft tissue of CNS from the cranium and vertebral canalSpecialized membranes that provide protection, physical stability, andshock absorptionspinal meningesContinuous with thecranial meningesConsist of three layers (superficial to deep):1.Dura materdura = tough2.Arachnoid mater3.Pia mater -adjacent to spinal tissue orbrain tissue
1. Dura materdural sheath surrounds spinal cordepidural spacebetween sheath andvertebral bones (occupied by bloodvessels, adipose tissue, and looseconnective tissue)Meninges2. Arachnoid Materadheres to the duraseparated from pia by the subarachnoid space:filled with cerebrospinal fluidlumbar puncture (spinal tap) takes samples of CSF at L3/L4 or L4/L5(no risk of spinal cord injury)
3. Pia Materdelicate membrane that follows the contoursof the spinal cordcontinues inferiorly as the fibrousterminalfilumthat fuses with the dura to form thecoccygeal ligamentMeninges
Spina bifidaCongenital defectOne or more vertebrae fail to form acomplete vertebral arch for enclosure ofthe spinal cord1 baby in 1,000Common in lumbosacral regionFolic acid(leafy greens) reduces incidenceNote - start 3 months before conception,as defect occurs in the first 4 weeks
Cross-sectional anatomy of the spinal cordGray matterGray matter surrounds acentral canalGray matter is calledhornsdue to theirshapeConsists of somas (cell bodies)Consists of glial cellsNeuron cell bodies with little myelin (siteof synaptic integration)White matterSurrounds gray matterAxons are organized into tracts orcolumnsAbundantly myelinated axons (carrysignals in the CNS)
Organization of Gray mattercentral core2 Posterior (dorsal) hornsPosterior root carries sensorynerve fibres2 Anterior (ventral) hornsAnterior (ventral) root of spinalnerve carries only motor fibresLateral hornVisible from T2 through L1Contains neurons of the sympathetic nervous systemGray commissureconnects right and left sidesCentral canallined with ependymal cells and filled with CSF
White matterSurrounds gray mattercolumnsof axons (funiculi)Columns containtractsof axons(ascending and descending tracts)Each column/funiculusconsists ofsubdivisions = Tracts or fasciculiColumns (funiculi):3 pairs of columns on each side1.Posterior (dorsal)2. Lateral3.Anterior (ventral)Columns convey either:Sensory tracts (ascending tracts)Motor tracts (descending tracts)Anterior white commissure
NerveCord-like organ composed of numerousnerve fibres (axons) bound together byconnective tissueMixed nerves contain both afferent andefferent fibres

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Term
Summer
Professor
Ju/Kee/French
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