The Nervous System: Spinal Nerves
14The Nervous System:The Spinal Cord andSpinal NervesPowerPoint Lecture Presentations prepared bySteven BassettSoutheast Community CollegeLincoln, Nebraska 2012 Pearson Education, Inc.
Introduction The Central Nervous System (CNS)consists of: The spinal cord Integrates and processes information Can function with the brain Can function independently of the brain The brain Integrates and processes information Can function with the spinal cord Can function independently of the spinal cord 2012 Pearson Education, Inc.
Gross Anatomy of the Spinal Cord Features of the Spinal Cord 45 cm in lengthPasses through the foramen magnumExtends from the brain to L1Consists of: Cervical regionThoracic regionLumbar regionSacral regionCoccygeal region 2012 Pearson Education, Inc.
Gross Anatomy of the Spinal Cord Features of the Spinal Cord Consists of (continued): Cervical enlargementLumbosacral enlargementConus medullarisCauda equinaFilum terminale: becomes a component of thecoccygeal ligament Posterior and anterior median sulci 2012 Pearson Education, Inc.
Figure 14.1a Gross Anatomy of the Spinal CordCervical 2T3T4T5T6T7ThoracicspinalnervesT8T9Posteriormedian arisL2LumbarspinalnervesL3L4Inferiortip ofspinal cordCauda equinaL5Sacral spinalnervesS1S2S3S4S5Coccygealnerve (Co1)Filum terminale(in coccygeal ligament)Superficial anatomy and orientation of the adult spinal cord. Thenumbers to the left identify the spinal nerves and indicate wherethe nerve roots leave the vertebral canal. The spinal cord, however,extends from the brain only to the level of vertebrae L1–L2. 2012 Pearson Education, Inc.
Gross Anatomy of the Spinal Cord Features of the Spinal Cord Transverse view White matterGray matterCentral canalDorsal root and ventral root: merge to form a spinalnerve Dorsal root is sensory: axons extend from thesoma within the dorsal root ganglion Ventral root is motor 2012 Pearson Education, Inc.
Figure 14.1d Gross Anatomy of the Spinal CordPosterior median sulcusDorsal rootDorsal rootganglionWhite Anterior median fissureC3T3L1S2Inferior views of cross sectionsthrough representativesegments of the spinal cordshowing the arrangement ofgray and white matter 2012 Pearson Education, Inc.
Gross Anatomy of the Spinal Cord Features of the Spinal Nerves Consist of: Sensory nerves (afferent nerves): transmitimpulses toward the spinal cord Motor nerves (efferent nerves): transmit impulsesaway from the spinal cord 2012 Pearson Education, Inc.
Figure 14.1d Gross Anatomy of the Spinal CordPosterior median sulcusDorsal rootDorsal rootganglionWhite Anterior median fissureC3T3L1S2Inferior views of cross sectionsthrough representativesegments of the spinal cordshowing the arrangement ofgray and white matter 2012 Pearson Education, Inc.
Spinal Meninges Features of spinal meninges: Specialized membranes that provide protection,physical stability, and shock absorption Continuous with the cranial (cerebral) meninges Denticulate ligaments help anchor the spinalcord in position Made of three layers Dura mater: tough, fibrous outermost layer Arachnoid mater: middle layer Pia mater: innermost layer 2012 Pearson Education, Inc.
Figure 14.2c The Spinal Cord and Spinal MeningesGray matterWhite matterVentral rootSpinal nerveDorsal rootPia materDorsal rootganglionArachnoid materDura materPosterior view of the spinal cord showing themeningeal layers, superficial landmarks, anddistribution of gray and white matter 2012 Pearson Education, Inc.
Figure 14.2a The Spinal Cord and Spinal MeningesSpinal cordAnterior medianfissurePia materDenticulateligamentsArachnoid mater(reflected)Dura mater(reflected)Spinal bloodvesselDorsal root ofsixth cervicalnerveVentral root ofsixth cervicalnerve 2012 Pearson Education, Inc.Anterior view of spinal cord showing meninges and spinal nerves. For thisview, the dura and arachnoid membranes have been cut longitudinally andretracted (pulled aside); notice the blood vessels that run in thesubarachnoid space, bound to the outer surface of the delicate pia mater.
Sectional Anatomy of the Spinal Cord Gray matter Central canal Consists of somas (cell bodies) surroundingthe central canal White matter Consists of axons Nerves are organized into tracts or columns Located outside the gray matter area 2012 Pearson Education, Inc.
Sectional Anatomy of the Spinal Cord Organization of Gray Matter Somas are organized into groups called nuclei Sensory nuclei Motor nuclei Transverse view shows: Posterior gray hornsLateral gray hornsAnterior gray hornsGray commissure 2012 Pearson Education, Inc.
Sectional Anatomy of the Spinal Cord Organization of gray matter Posterior gray horns: somatic sensory andvisceral nuclei Lateral gray horns: visceral motor nuclei Anterior gray horns: somatic motor nuclei Gray commissure Consists of axons crossing from one side to theother 2012 Pearson Education, Inc.
Figure 14.4b Sectional Organization of the Spinal CordPosterior median sulcusFrom dorsal rootPosteriorgray hornPosterior graycommissureSomaticVisceralLateralgray hornVisceralAnteriorgray hornSomaticAnterior graycommissureSensorynucleiMotornucleiTo ventralrootAnterior medianfissureThe left half of this sectional view shows important anatomical landmarks; the right half indicatesthe functional organization of the gray matter in the anterior, lateral, and posterior gray horns. 2012 Pearson Education, Inc.
Sectional Anatomy of the Spinal Cord Organization of white matter Consists of columns of nerves (fascicles) Columns convey either: Sensory tracts (ascending tracts) Motor tracts (descending tracts) 2012 Pearson Education, Inc.
Figure 14.4c Sectional Organization of the Spinal CordLegPosterior whitecolumn or whitecolumn (funiculus)Anterior whitecommissureThe left half of this sectional view shows the major columns of white matter. The right halfindicates the anatomical organization of sensory tracts in the posterior white column forcomparison with the organization of motor nuclei in the anterior gray horn. Note that bothsensory and motor components of the spinal cord have a definite regional organization. 2012 Pearson Education, Inc.
Spinal Nerves There are 31 pairs of spinal nerves 8 cervical nerves12 thoracic nerves5 lumbar nerves5 sacral nerves1 coccygeal nerve 2012 Pearson Education, Inc.
Figure 14.1a Gross Anatomy of the Spinal CordCervical 2T3T4T5T6T7ThoracicspinalnervesT8T9Posteriormedian arisL2LumbarspinalnervesL3L4Inferiortip ofspinal cordCauda equinaL5Sacral spinalnervesS1S2S3S4S5Coccygealnerve (Co1)Filum terminale(in coccygeal ligament)Superficial anatomy and orientation of the adult spinal cord. Thenumbers to the left identify the spinal nerves and indicate wherethe nerve roots leave the vertebral canal. The spinal cord, however,extends from the brain only to the level of vertebrae L1–L2. 2012 Pearson Education, Inc.
Spinal Nerves Spinal nerves Each peripheral nerve consists of: Epineurium: outer layer – becomes continuouswith the dura mater Perineurium: layer surrounding a fascicle – afascicle is a bundle of axons Endoneurium: layer surrounding a single axon 2012 Pearson Education, Inc.
Figure 14.5a Anatomy of a Peripheral NerveBlood vesselsConnective TissueLayersEpineurium coveringperipheral nervePerineurium (aroundone fascicle)EndoneuriumSchwann cellMyelinatedaxonA typical peripheralnerve and its connectivetissue wrappings 2012 Pearson Education, Inc.Fascicle
Spinal Nerves Peripheral Distribution of Spinal Nerves Four branches of the spinal nerves: White ramus Gray ramus White and gray ramus are collectively called ramicommunicantes Dorsal ramus Ventral ramus 2012 Pearson Education, Inc.
Spinal Nerves Branches of the spinal nerves (details) Rami communicantes (white and grayramus) Innervates smooth muscles, glands, and organs Motor impulses leave the spinal cord through theventral root to the spinal nerves Dorsal ramus Innervates skeletal muscles of the neck and back Ventral ramus Innervates skeletal muscles of the limbs 2012 Pearson Education, Inc.
Figure 14.6a Peripheral Distribution of Spinal NervesMotor CommandsPostganglionic fibersto smooth muscles,glands, etc., of backTo skeletalmuscles of backDorsalDorsal root ganglion rootVisceral Somaticmotor motorDorsal ramusVentral ramusTo skeletalmuscles of bodywall, limbsVentralrootPostganglionic fibers tosmooth muscles, glands,etc., of body wall, limbsSpinal nerveSympathetic ganglionGray ramus(postganglionic)RamicommunicantesWhite ramus(preganglionic)Sympathetic nervePostganglionic fibersto smooth muscles,glands, visceral organsin thoracic cavityKEYSomatic motorcommandsVisceral motorcommandsPreganglionic fibers tosympathetic gangliainnervating abdominopelvic visceraThe distribution of motor neurons in the spinal cord and motor fibers within the spinalnerve and its branches. Although the gray ramus is typically proximal to the white ramus,this simplified diagrammatic view makes it easier to follow the relationships betweenpreganglionic and postganglionic fibers. 2012 Pearson Education, Inc.
Spinal Nerves Sensory impulses associated with thespinal nerves Sensory impulses travel in the spinal nervethrough the dorsal root to the spinal cord 2012 Pearson Education, Inc.
Figure 14.6b Peripheral Distribution of Spinal NervesSensory InformationFrom interoceptorsof backFrom exteroceptors,proprioceptors of backDorsalrootSomatic Visceralsensory sensoryDorsal ramusVentral ramusFrom exteroceptors,proprioceptors ofbody wall, limbsDorsalrootganglionFrom interoceptorsof body wall, onsVisceralsensationsFrom interoceptorsof visceral organsA comparable view detailing the distribution of sensory neurons and sensory fibers 2012 Pearson Education, Inc.
Spinal Nerves Dermatomes Each pair of spinal nerves monitors specificsurface areas These are clinically important areas regardingsurgery 2012 Pearson Education, Inc.
Figure 14.7 C3C4C5T1T2T3T4T5T6T7T8T9T 10T 11T 12T2T3T4T5T6T7T8T9T 10T 11T 12L1L2L4 L3L5C4C5T2C6T1C7SSS24 3L1S5C8S1 L5L2 S2L3S1L4ANTERIOR 2012 Pearson Education, Inc.POSTERIOR
Nerve Plexuses There are four nerve plexuses Cervical plexusBrachial plexusLumbar plexusSacral plexus Sometimes the lumbar and sacral are combined toform the lumbosacral plexus 2012 Pearson Education, Inc.
Figure 14.8 Peripheral Nerves and Nerve C8T1T2T3T4T5T6T7T8Lesser occipital nerveGreat auricular nerveTransverse cervical nerveSupraclavicular nervePhrenic nerveAxillary nerveMusculocutaneousnerveT9Thoracic nervesT10T11T12Radial nerveL1LumbarplexusL2Ulnar nerveL3SacralplexusL4L5S1S2S3S4S5Co1Median moralnerveFemoral nerveObturator nerveSuperiorInferiorGlutealnervesPudendal nerveSciatic nerveLateral femoral cutaneous nerveSaphenous nerveCommon fibular nerveTibial nerveMedial sural cutaneous nerve 2012 Pearson Education, Inc.
Nerve Plexuses The Cervical Plexus (C1–C5) Consists of cutaneous and muscularbranches Cutaneous branch innervates: Head Neck Chest 2012 Pearson Education, Inc.
Nerve Plexus The Cervical Plexus Consists of cutaneous and muscularbranches Muscular branch innervates: Omohyoid, sternohyoid, geniohyoid, Levator scapulaeTrapeziusDiaphragm (controlled by the phrenic nerve of thecervical plexus) 2012 Pearson Education, Inc.
Figure 14.9 The Cervical PlexusAccessorynerve (N XI)CranialHypoglossalnervesnerve (N XII)Great auricular nerveLesser occipitalnerveC1C2Nerve roots ofcervical d muscleTransversecervical nerveThyrohyoid muscleAnsa cervicalisOmohyoid musclePhrenic nerveSternohyoid muscleSternothyroid muscle 2012 Pearson Education, Inc.
Nerve Plexus The Brachial Plexus (C4–T1) The immediate nerves emerging from C5 to T1are the: Superior trunk Middle trunk Inferior trunk These trunks all merge to form the lateral cord 2012 Pearson Education, Inc.
Figure 14.10b The Brachial PlexusDorsal scapular nerveSuprascapular nerveC4C5C6C7C8Superior trunkMiddle trunkBRACHIALPLEXUS Inferior trunkT1MusculocutaneousnerveMedian nerveUlnar nerveRadialnerveLateral antebrachialcutaneous nerveDeep radial nerveSuperficial branchof radial nerveUlnar nerveMedian nerveAnterior interosseous nerveRadial nerveDeep branch of ulnar nerveSuperficial branch of ulnar nerveUlnar nervePalmar digital nervesMedian nerveAnterior view of the brachial plexus and upper limbshowing the peripheral distribution of major nerves 2012 Pearson Education, Inc.AnteriorDistribution ofcutaneous nerves
Nerve Plexus The cords of the brachial plexus Lateral cord: merging of the trunks Medial cord: an extension of the inferior trunk Posterior cord: an extension of the middletrunk 2012 Pearson Education, Inc.
Figure 14.10a The Brachial PlexusKEYDorsal scapularnerveRoots (ventral rami)Nerve tosubclavius muscleTrunksC5DivisionsSUPERIOR TRUNKCordsC6Peripheral nervesSuprascapular nerveMIDDLETRUNKLateral cordC7BRACHIALPLEXUSPosterior cordC8Lateral pectoral nerveMedial pectoral nerveSubscapular nervesT1Axillary nerveMedial cordFirstribMusculocutaneousnerveMedial antebrachialcutaneous nerveMedian nerveINFERIORTRUNKLong thoracicnerveThoracodorsalnerveUlnar nervePosterior brachialcutaneous nerve 2012 Pearson Education, Inc.Radial nerveThe trunks and cords of the brachialplexus
Nerve Plexus The cords of the brachial plexus (details) Lateral cord: extends to form themusculocutaneous nerve The lateral cord and medial cord extend toform the median nerve Medial cord extends to form the ulnar nerve Posterior cord: branches to form the radialnerve and axillary nerve 2012 Pearson Education, Inc.
Figure 14.10a The Brachial PlexusKEYDorsal scapularnerveRoots (ventral rami)Nerve tosubclavius muscleTrunksC5DivisionsSUPERIOR TRUNKCordsC6Peripheral nervesSuprascapular nerveMIDDLETRUNKLateral cordC7BRACHIALPLEXUSPosterior cordC8Lateral pectoral nerveMedial pectoral nerveSubscapular nervesT1Axillary nerveMedial cordFirstribMusculocutaneousnerveMedial antebrachialcutaneous nerveMedian nerveINFERIORTRUNKLong thoracicnerveThoracodorsalnerveUlnar nervePosterior brachialcutaneous nerve 2012 Pearson Education, Inc.Radial nerveThe trunks and cords of the brachialplexus
Figure 14.10b The Brachial PlexusDorsal scapular nerveSuprascapular nerveC4C5C6C7C8Superior trunkMiddle trunkBRACHIALPLEXUS Inferior trunkT1MusculocutaneousnerveMedian nerveUlnar nerveRadialnerveLateral antebrachialcutaneous nerveDeep radial nerveSuperficial branchof radial nerveUlnar nerveMedian nerveAnterior interosseous nerveRadial nerveDeep branch of ulnar nerveSuperficial branch of ulnar nerveUlnar nervePalmar digital nervesMedian nerveAnterior view of the brachial plexus and upper limbshowing the peripheral distribution of major nerves 2012 Pearson Education, Inc.AnteriorDistribution ofcutaneous nerves
Figure 14.10c The Brachial PlexusMusculocutaneousnerveAxillary nerveBranches ofaxillary nerveRadial nerveUlnar nerveMedian nervePosterior antebrachialcutaneous nerveDeep branch ofradial nerveSuperficial branchof radial nerveRadialnerveDorsal digital nervesUlnarnerveMediannervePosteriorDistribution ofcutaneous nerves 2012 Pearson Education, Inc.Posterior view of the brachial plexus andthe innervation of the upper limb
Figure 14.11 The Cervical and Brachial PlexusesClavicle, cutand removedDeltoid muscleMusculocutaneousnerveRight axillary arteryover axillary nerveMedian nerveRadial nerveBiceps brachii,long and short headsCervicalplexusRight commoncarotid arteryBrachial plexus(C5–T1)Sternocleidomastoid muscle,sternal headSternocleidomastoid muscle,clavicular headRight subclavianarteryUlnar nerveCoracobrachialismuscleSkinRight brachialarteryMediannerve 2012 Pearson Education, Inc.Retractor holdingpectoralis majormuscle (cut andreflected)
Table 14.2 The Brachial Plexus 2012 Pearson Education, Inc.
Nerve Plexus The Lumbar and Sacral Plexuses (T12–S4) Also called the lumbosacral plexus Lumbar plexus nerves Genitofemoral nerve Lateral femoral cutaneous nerve Femoral nerve Sacral plexus nerves Sciatic nerve (branches to form the commonfibular nerve and the tibial nerve) Pudendal nerve 2012 Pearson Education, Inc.
Figure 14.12a The Lumbar and Sacral Plexuses, Part IT12T12 subcostal nerveL1Iliohypogastric nerveL2LUMBARPLEXUSIlioinguinal nerveL3Genitofemoral nerveLateral femoralcutaneous nerveBranches ofFemoral branchgenitofemoralnerve Genital branchFemoral nerveObturator nerveL4L5LumbosacraltrunkThe lumbar plexus, anterior view 2012 Pearson Education, Inc.
Figure 14.12b The Lumbar and Sacral Plexuses, Part IL5Lumbosacral trunkS1Superior gluteal nerveInferior gluteal nerveS2SACRALPLEXUSS3S4Sciatic nervePosterior femoralcutaneous nervePudendal nerveS5Co1The sacral plexus, anterior view 2012 Pearson Education, Inc.
Figure 14.12c The Lumbar and Sacral Plexuses, Part ISubcostal nerveIliohypogastric nerveIlioinguinal nerveGenitofemoral nerveLateral femoralcutaneous nerveFemoral nerveSuperior gluteal nerveInferior gluteal nervePudendal nervePosterior femoralcutaneous nerve (cut)Obturator nerveSciatic nerveSaphenousnerveSaphenous nerveSuralnerveFibularnerveCommon fibularnerveTibialnerveSuperficial fibularnerveDeep fibularnerveSuralnerveSaphenousnerveThe lumbar and sacralplexuses, anterior view 2012 Pearson Education, e
Table 14.3 The Lumbar and Sacral Plexuses 2012 Pearson Education, Inc.
Figure 14.12d The Lumbar and Sacral Plexuses, Part ISuperior gluteal nerveInferior gluteal nervePudendalnervePosterior femoralcutaneous nerveSciatic nerveSaphenousnerveSuralnerveFibularnerveTibial nerveCommon fibularnerveMedial suralcutaneous nerveLateral suralcutaneous nerveTibialnerveSuralnerveSaphenousnerveSural nerveSaphenousnerveTibialnerve 2012 Pearson Education, Inc.SuralnerveFibularnerveMedial plantarnerveLateral plantarnerveThe sacral plexus,posterior view
Figure 14.13c The Lumbar and Sacral Plexuses, Part II (Part 1 of 2)Gluteus maximus(cut)Inferior glutealnervePudendal nervePerineal branchHemorrhoidalbranchGluteus medius(cut)Gluteus minimusSuperior glutealnervePiriformisPosterior femoralcutaneous nervePerineal endinosusA diagrammatic posterior view of theright hip and lower limb detailing thedistribution of peripheral nerves 2012 Pearson Education, Inc.Biceps femoris(cut)
Figure 14.13c The Lumbar and Sacral Plexuses, Part II (Part 2 of 2)Tibial nervePopliteal arteryand veinMedial suralcutaneousnerveCommon fibularnerveLateral suralcutaneousnerveGastrocnemiusSmall saphenousveinSural nerveCalcaneal tendonTibial nerve(medial calcanealbranch)A diagrammatic posterior view of theright hip and lower limb detailing thedistribution of peripheral nerves 2012 Pearson Education, Inc.
Figure 14.13a The Lumbar and Sacral Plexuses, Part IIGluteus maximusSuperior gluteal nerveInferior gluteal nerveGluteus mediusGluteus minimusInternalpudendalarteryPudendalnerveNerve togemellusandobturatorinternusA dissection of the right gluteal region 2012 Pearson Education, Inc.Tibial branchCommon fibular Components ofsciatic nervebranchGreater trochanter of femurPosterior femoralcutaneous nerveGluteusmaximus
Figure 14.13b The Lumbar and Sacral Plexuses, Part IIBiceps femorisSartoriusGracilisSemimembranosusPopliteal arterySemitendinosusNerve tomedial headof gastrocnemiusGastrocnemius,medial headMedial suralcutaneous nerveA dissection of the popliteal fossa 2012 Pearson Education, Inc.Tibial nerveLateral suralcutaneous nerveCommon fibularnervePlantarisNerve to lateral headof gastrocnemiusGastrocnemius,lateral head
Nerve Plexus Summary of the spinal nerves Cervical spinal nerves emerge from C1–C8Thoracic spinal nerves emerge from T1–T12Lumbar spinal nerves emerge from L1–L5Sacral spinal nerves emerge from S1–S5Coccygeal spinal nerves emerge from Co1 2012 Pearson Education, Inc.
Nerve Plexus Summary of the nerve plexuses Cervical plexus nerves emerge from C1–C5Brachial plexus nerves emerge from C5–T1There is not a thoracic plexusLumbar plexus nerves emerge from T12–L4Sacral plexus nerves emerge from L4–S4There is not a coccygeal plexus 2012 Pearson Education, Inc.
Figure 14.3 Posterior View of Vertebral Column and Spinal NervesOccipital boneSpinal cordemerging fromforamen C1–C8 4)Coccygeal nerves (Co1) 2012 Pearson Education, Inc.Lumbarplexus(T12–L4)SciaticnerveSacral spinalnerves (S1–S5)emerging fromsacral foramina
Reflexes Reflex An immediate involuntary response Reflex arc The neural “wiring” of a single reflex Begins at a sensory receptor and ends at aperipheral receptor 2012 Pearson Education, Inc.
Reflexes Reflexes are classified according to: Their development Innate or acquired The site where information is processed Spinal or cranial (cerebral) The nature of the resulting motor response Somatic, visceral, or autonomic The complexity of the neural circuit Monosynaptic or polysynaptic 2012 Pearson Education, Inc.
Reflexes Pathway of a reflex arc 1. Activation of a sensory receptor2. Relay of information to the CNS3. Information processing4. Activation of a motor neuron5. Response by the effectorANIMATION Components of a Reflex Arc 2012 Pearson Education, Inc.
Figure 14.14 A Reflex ArcDorsalrootActivation of asensory neuronArrival of stimulus andactivation of receptorSensationrelayed tothe brain nse by effectorVentralrootActivation of amotor neuronInformation processingin CNSKEYSensory neuron(stimulated)ExcitatoryinterneuronMotor neuron(stimulated) 2012 Pearson Education, Inc.
Figure 14.15 The Classification of ReflexesReflexescan be classified bydevelopmentresponsecomplexity of circuitprocessing siteInnate ReflexesSomatic ReflexesMonosynapticSpinal Reflexes Geneticallydetermined Control skeletal muscle contractions Include superficial and stretch reflexes One synapse Processing inthe spinal cordAcquired ReflexesVisceral (Autonomic) ReflexesPolysynapticCranial Reflexes Learned Control actions of smooth andcardiac muscles, glands Multiple synapses(two to several hundred) Processing inthe brain 2012 Pearson Education, Inc.
Reflexes Spinal reflexes can be: Monosynaptic Involves a single segment of the spinal cord Polysynaptic Integrates motor output from several spinalsegments 2012 Pearson Education, Inc.
Figure 14.16 Neural Organization and Simple euronInterneuronsCircuit 2MotorneuronMotorneuronsCircuit 1Sensoryreceptor(musclespindle)Skeletal muscle 1Skeletal muscleA monosynaptic reflex circuit involves a peripheralsensory neuron and a central motor neuron. In thisexample, stimulation of the receptor will lead to areflexive contraction in a skeletal muscle. 2012 Pearson Education, Inc.Skeletal muscle 2A polysynaptic reflex circuit involves a sensory neuron,interneurons, and motor neurons. In this example, thestimulation of the receptor leads to the coordinatedcontractions of two different skeletal muscles.
Reflexes Stretch reflex 1. Stimulus stretches a muscle2. Activates a sensory neuron3. Information is processed in the spinal cord4. Motor neurons are activated5. Muscle (effector) contracts 2012 Pearson Education, Inc.
Figure 14.17a Stretch ReflexesActivation of asensory neuronStimulus. Stretching of musclestimulates muscle spindlesInformation processingat motor neuronResponse. Contractionof muscleActivation ofmotor neuronSteps 1–5 are common to all stretch reflexes. 2012 Pearson Education, Inc.KEYSensory neuron(stimulated)Motor neuron(stimulated)
Figure 14.17b Stretch ReflexesReceptor(musclespindle)Spinal Sensory neuron(stimulated)Motor neuron(stimulated)Response 2012 Pearson Education, Inc.The patellar reflex is controlled by muscle spindles in the quadriceps group. Thestimulus is a reflex hammer striking the muscle tendon, stretching the spindlefibers. This results in a sudden increase in the activity of the sensory neurons,which synapse on spinal motor neurons. The response occurs upon the activationof motor units in the quadriceps group, which produces an immediate increase inmuscle tone and a reflexive kick.
2012 Pearson Education, Inc. Figure 14.2a The Spinal Cord and Spinal Meninges Anterior view of spinal cord showing meninges and spinal nerves.
The human nervous system: The human nervous system is subdivided into two main sections i.e. Central nervous system – consisting of the brain and spinal cord Peripheral nervous system – consisting of nerves that conduct impulses to and from the brain and spinal cord. It includes 12 pairs of cranial nerves and 31 pairs of spinal nerves.
tem into the peripheral nervous system and the central nervous system. We discuss each in turn. The Peripheral Nervous System The peripheral nervous system in Figure 1.2 shows the 31 pairs of spinal nerves. They are called "spinal" because they carry information to and from the spinal cord (Heimer,1983).There are also 12 cranial nerves that .
I. Central Nervous System vs Peripheral Nervous System II. Peripheral Nervous System A. Somatic Nervous System B. Autonomic Nervous System III. Autonomic Nervous System A. Parasympathetic Nervous System B. Sympathetic Nervous System IV. Reflex Actions V. Central Nervous Sys
May 02, 2018 · D. Program Evaluation ͟The organization has provided a description of the framework for how each program will be evaluated. The framework should include all the elements below: ͟The evaluation methods are cost-effective for the organization ͟Quantitative and qualitative data is being collected (at Basics tier, data collection must have begun)
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The nervous system has two main anatomical divisions: A. The central nervous system (CNS) represented by the brain and spinal cord B. The peripheral nervous system (PNS) represented by the spinal nerves, cranial nerves and autonomic nervous system (ANS) N.B. In the CNS the collec
peripheral nervous system is subdivided into the a. sensory-somatic nervous system and the autonomic nervous system (ANS). The peripheral nervous system carry information to and from the central nervous system. The central nervous system is composed of the brain and spinal cord. Figure 1 The Human Nervous System
Mar 25, 2014 · Nervous System Divisions of the Nervous system Central Nervous System – relays messages, processes information, and analyzes information; Consists of brain and spinal cord Meninges – connective tissue around the brain and spinal cord Cerebrospinal fluid – Cushions the brain and spinal cord inside meninges Peripheral Nervous System-- Receives
