Motor Systemssystems

MotorMotor systemssystems

ControlControl ofof movementmovement Motor neuron DRG ElementsElements ofof motormotor systemsystem

Effectors MOTOR SYSTEM

Skeletal Muscle SOMATIC MOTOR SYSTEM

Smooth Muscle AUTONOMIC MOTOR SYSTEM Glands (sympathetic and Parasympathetic) MajorMajor somaticsomatic motormotor systemssystems

LowerLower motormotor neuronsneurons –– spinalspinal cordcord UpperUpper motormotor neuronsneurons –– neocortexneocortex CerebellumCerebellum BasalBasal gangliaganglia BasicBasic componentscomponents ofof motormotor circuitscircuits

MotorMotor cortexcortex Basal ganglia Cerebellum BrainstemBrainstem centerscenters && SpinalSpinal cordcord

Muscles ControlControl ofof movementmovement AnteriorAnteriorAnterior HornHornHorn CellCellCell --Lower Lower MotorMotor NeuronNeuron --

AHC MotorMotor unitunit = 11 motoneuronmotoneuron + musclemuscle fibersfibers

Motor unit innervation ratios (motoneuron/muscle fibers innervated) eyes, ear - 1:10 hands - 1:100 soleus (posture) - 1:180 gastrocnemius (jumping) - 1:1000- 2000

Each muscle fiber receives input from only one motor neuron SpinalSpinal reflexesreflexes

Purves, et al, Neuroscience, 3rd ed. The stretch reflex operates as a negative feedback loop to regulate muscle length

Purves, et al, Neuroscience, 3rd ed. DiseasesDiseases ofof thethe motormotor unitunit

(disease of nerve) (disease of muscle)

Kandel, Schwartz, Jessell; Principles of Neural Science, 4 th ed. NeurogenicNeurogenic vsvs myopathicmyopathic diseasesdiseases ofof thethe motormotor unitunit

Finding Neurogenic disease Myopathic disease Weakness + + + + Wasting + + Loss of reflexes + (ALS) 0 Fasciculations + (PN) 0 Sensory loss + (PN) 0 Hyperreflexia, Babinski sign + (ALS) 0

Kandel, Schwartz, Jessell; Principles of Neural Science, 4 th ed. LowerLower motormotor neuronsneurons (LMN)(LMN)

SpinalSpinal CordCord AnteriorAnterior Horn Horn Cell Cell (Lamina (Lamina IX) IX) ------spinal spinal n. n. BrainBrain StemStem GeneralGeneral Somatic Somatic Efferent Efferent (GSE) (GSE) Nuclei Nuclei HypoglossalHypoglossal Nucleus Nucleus ------XII XII AbducensAbducens Nucleus Nucleus ------VI VI TrochlearTrochlear Nucleus Nucleus ------IV IV OculomotorOculomotor Nucleus Nucleus ------III III SpecialSpecial Visceral Visceral Efferent Efferent (SVE) (SVE) Nuclei Nuclei AmbiguusAmbiguus Nucleus Nucleus ------IX, IX, X, X, XI XI FacialFacial (Motor) (Motor) Nucleus Nucleus ------VII VII TrigeminalTrigeminal Motor Motor Nucleus Nucleus ------V V Distribution of LMN pools: somatotopic arrangement

dorsal

Flexor muscles

(posture) (fine movement) Extensor muscles

ventral SpinalSpinal locallocal circuitcircuit neuronsneurons areare alsoalso arrangedarranged somatotopicallysomatotopically

MedialMedial projectproject toto manymany segmentssegments andand supplysupply medialmedial MNsMNs -- postureposture LateralLateral projectproject toto 11 oror fewfew segmentssegments andand supplysupply laterallateral MNsMNs –– finefine movementsmovements

Purves, et al, Neuroscience, 3rd ed. Upper motor neurons are also arranged somatotopically

BrainstemBrainstem →→ spinalspinal medialmedial MNsMNs -- postureposture NeocortexNeocortex →→ spinalspinal laterallateral MNsMNs –– finefine movementsmovements UpperUpper motormotor neuronneuron (UMN)(UMN) = pyramidalpyramidal tracttract

Pyramidal tract

Corticobulbar tract

Corticospinal tract UMNUMN –– corticospinalcorticospinal tracttract

Origin:Origin: CerebralCerebral CortexCortex BrodmannBrodmann Area Area 4 4 (Primary (Primary Motor Motor Area, Area,M M I) I) BrodmannBrodmann Area Area 6 6 (Premotor (Premotor Area, Area, PM PM ) ) BrodmannBrodmann Area Area 3,1,2 3,1,2 (Primary (Primary Somesthetic Somesthetic Area, Area, S S I) I) BrodmannBrodmann Area Area 5 5 (Anterior (Anterior Portion Portion of ofSup. Sup. Parietal Parietal Lobule) Lobule) CoronaCorona Radiata Radiata lnternallnternal Capsule, Capsule, Posterior Posterior Limb Limb CrusCrus Cerebri, Cerebri, MiddleMiddle Portion Portion LongitudinalLongitudinal Pontine Pontine Fiber Fiber PyramidPyramid - -pyramidal pyramidal decussation decussation CorticospinalCorticospinal Tract Tract - -Lateral Lateral and and Anterior Anterior Termination:Termination: SpinalSpinal GrayGray ( (RexedRexed IV IV-IX)-IX) CorticospinalCorticospinal TractTract BA 4

T Posterior Limb IC A Cerebral Peduncles F

Longitudinal Fibers Pons

Pyramids ±Decussation

Origin: Primary motor cortex (BA 4) Spinal Cord Course: Post Limb IC, Pyramids 90% Lat, 10% Ant Termination: Spinal cord ventral horn Laterality: CONTRA (lateral), IPSI (anterior) CorticospinalCorticospinal TractTract

Origin: Primary motor cortex (BA 4) Course: Post Limb IC, Pyramids Termination: Spinal cord ventral horn Laterality: CONTRA (lateral), IPSI (anterior) CorticospinalCorticospinal TractTract

Origin: Primary motor cortex (BA 4) Course: Post Limb IC, Pyramids Termination: Spinal cord ventral horn Laterality: CONTRA (lateral), IPSI (anterior) 90% of the fibers decussate and become the lateral corticospinal CorticospinalCorticospinal TractTract tract; the remaining 10% of fibers remain ipsilateral and become the anterior corticospinal tract

Origin: Primary motor cortex (BA 4) Course: Post Limb IC, Pyramids Termination: Spinal cord ventral horn Laterality: CONTRA (lateral), IPSI (anterior) Lateral CorticospinalCorticospinal TractTract CST

Anterior CST Descending neurons synapse on Origin: Primary motor cortex (BA 4) interneurons or Course: Post Limb IC, Pyramids motoneurons in the Termination: Spinal cord ventral horn ventral horn of the Laterality: CONTRA (lateral), IPSI (anterior) spinal cord CCorticospinalorticospinal tracttract -- summarysummary

Terminates on inhibitory INs in spinal cord Essential for skill and precision in movement and the execution of discrete fine finger movements Myelination completes by 2 nd year → time of standing/walking Lesions of CST result in paralysis (UMN disease) lesion above decussation → paralysis is contralateral lesions below decussation → paralysis is ipsilateral Corticospinal tract - summary UMNUMN vsvs LMNLMN diseasedisease

Fundamentals of neurologic disease : an introductory text / Larry E. Davis, 2005 BabinskiBabinski signsign →→ UMNUMN damagedamage

Purves, et al, Neuroscience, 3rd ed. AtrophyAtrophy →→ LMNLMN damagedamage

Distinguish neurogenic from myopathic atrophy! UMNUMN –– corticobulbarcorticobulbar tracttract

- Corticofugal fibers projecting to, and terminating in the portions of lower brainstem

- Termination: 1) motor nuclei (upper motor neuron pathway) hypoglossal, ambiguus , facial motor, trigeminal motor, abducens , trochlear and oculomotor nucleus 2) sensory relay nuclei nuclei gracilis and cuneatus, trigeminal sensory nucleus, solitary tract nucleus 3) reticular formation (corticoreticular fiber) Corticobulbar Tracts

T A

Genu of internal capsule

Upper part only

Origin: Primary motor cortex (BA 4), face portion Course: Internal Capsule (genu), cerebral peduncles, longitudinal fibers of the pons, pyramids Termination: Motor nuclei of the cranial nerves Laterality: CN motor nuclei – V , VII (upper face), Ambiguus: BILATERAL CN motor nuclei - VII (lower face), XII: Contralateral CorticospinalCorticospinal vsvs corticobulbarcorticobulbar pathwayspathways IntegrationIntegration ofof directdirect andand indirectindirect neocorticalneocortical pathwayspathways toto spinalspinal cordcord

CortexCortex

Limb fine Postural movements BrainstemBrainstem adjustments to movements

SpinalSpinal cordcord MMedialedial andand thethe laterallateral brainbrain stemstem pathwayspathways

teticulospinal rubrospinal vestibulospinal tectospinal MedialMedial vsvs laterallateral tractstracts

MedialMedial tractstracts terminateterminate onon axialaxial andand proximalproximal muscles;muscles; activateactivate extensorextensor musculaturemusculature LateralLateral tractstracts terminateterminate onon appendicularappendicular muscles,muscles, inin particularparticular distaldistal extremitiesextremities AllAll descendingdescending tracttract terminateterminate onon interneuronsinterneurons -- exceptexcept corticospinalscorticospinals forfor fingerfinger controlcontrol (direct(direct toto motoneurons)motoneurons) MedialMedial && laterallateral tractstracts

VestibulospinalVestibulospinal –– laterallateral forfor antigravityantigravity muscles;muscles; medialmedial forfor headhead positionposition ReticulospinalReticulospinal –– tonetone andand posture;posture; pontinepontine toto extensors,extensors, medullarymedullary toto flexorsflexors TectospinalTectospinal –– headhead andand eyeeye orientationorientation toto aa distinctdistinct stimulusstimulus (visual,(visual, auditory,auditory, tactile)tactile) CorticospinalCorticospinal –– finefine fingerfinger control;control; moremore forfor armsarms thanthan legslegs RubrospinalRubrospinal –– finefine fingerfinger controlcontrol VestibulospinalVestibulospinal TractsTracts

MedialMedial VSTVST Balance of head and neck Extensor bias LateralLateral VSTVST Balance of trunk, limb girdle, proximal limbs Extensor bias VestibulospinalVestibulospinal TractsTracts

Vestibular Nuclei run at three different levels: • Level of CN VI & VII • Level of CN VIII & IX • Level of CN X & XII VestibulospinalVestibulospinal TractsTracts

Origin: Lateral/Medial Vestibular Nuclei Course: MVST: Within MLF below VI and ventromedial spinal cord LVST: unclear in brainstem, then in ventromedial spinal cord Termination: MVST: ventral gray, cervical and high thoracic LVST: ventral gray, all levels Laterality: MVST: bilateral LVST: ipsilateral VestibulospinalVestibulospinal TractsTracts MVST (bilateral)

Vestibular Nuclei

Origin: Lateral/Medial Vestibular Nuclei Course: MVST: Within MLF below VI and ventromedial spinal cord LVST: unclear in brainstem, then in ventral spinal cord Termination: MVST: ventral gray, cervical and high thoracic LVST: ventral gray, all levels Laterality: MVST: bilateral LVST: ipsilateral MVST VestibulospinalVestibulospinal TractsTracts (bilateral)

Vestibular Nuclei

Origin: Lateral/Medial Vestibular Nuclei Course: MVST: Within MLF below VI and ventromedial spinal cord LVST: unclear in brainstem, then in ventral spinal cord Termination: MVST: ventral gray, cervical and high thoracic LVST: ventral gray, all levels Laterality: MVST: bilateral LVST: ipsilateral VestibulospinalVestibulospinal TractsTracts MVST LVST (bilateral)

PontinePontine RSTRST Postural / axial movement and muscle tone Extensor bias MedullaryMedullary RSTRST Postural / axial movement and muscle tone Flexor bias Pontine and Medullary Reticulospinal Tract

Pontine Reticular Formation

Origin: Pontine reticular formation/Medullary reticular formation Course: PRST: Ventromedial spinal cord MRST: Lateral spinal cord Termination: PRST: Ventral gray of spinal cord, all levels MRST: Ventral gray of spinal cord, all levels Laterality: PRST: Ipsilateral MRST: Bilateral, with an ipsilateral bias Pontine and Medullary Reticulospinal Tract

Pontine Reticular Formation

Medullary Reticular Formation

PRST Origin: Pontine reticular formation/Medullary reticular formation Course: PRST: Ventromedial spinal cord MRST: Lateral spinal cord Termination: PRST: Ventral gray of spinal cord, all levels MRST: Ventral gray of spinal cord, all levels Laterality: PRST: Ipsilateral MRST: Bilateral, with an ipsilateral bias TectospinalTectospinal tracttract

ReflexiveReflexive movementmovement ofof headhead andand neckneck AssociatedAssociated withwith eyeeye movementsmovements TectospinalTectospinal TractTract

Origin: Superior Colliculus Course: Ventral to MLF, to ventromedial Spinal Cord Termination: Cervical Spinal cord ventral horn Laterality: CONTRA (crosses immediately in the dorsal tegmental decussation) TectospinalTectospinal TractTract

Ventromedial Group

GrossGross movementsmovements ofof upperupper extremitiesextremities FlexorFlexor biasbias RubrospinalRubrospinal TractTract

Origin: Red nucleus Course: Dorsolateral white matter with LCST in spinal cord Termination: Cervical Spinal cord ventral horn Laterality: CONTRA (crosses immediately in the ventral tegmental decussation) Summary of tracts Principle Spinal Cord Flexor/Extensor Tract Source Targeted Function Location Bias Musculature Lateral and medial Lateral & Posture, axial vestibular medial Ventromedial Extensor Axial/proximal movement & nucleus in the vestibulospinal muscle tone dorsolateral medulla

Nucleus Posture, axial Pontine reticularis Ventromedial Extensor Axial/proximal movement & reticulospinal pontis muscle tone (Medial) Nucleus Posture, axial Medullary reticularis Lateral Flexor Axial/proximal movement and reticulospinal gigantocellula- muscle tone (Lateral) ris Distal, Lateral Cerebral cortex Lateral Minimal Distal precision corticospinal movement Head Deep layers of movements Tecto-reticulo- superior Ventromedial None Axial required for spinal colliculus orienting reactions Feedforward and feedback mechanisms of postural control

Purves, et al, Neuroscience, 3rd ed. NeocorticalNeocortical motormotor areasareas

M1M1 PremotorPremotor areasareas Ventral PM area (PMv) Dorsal PM area (PMd) Supplementary motor area (SMA) Cingulate motor area (CMA)

Kandel, Schwartz, Jessell; Principles of Neural Science, 4 th ed. SomatotopicSomatotopic organizationorganization ofof M1M1

Blood supply of M1

Wilder Penfield

Kandel, Schwartz, Jessell; Principles of Neural Science, 4 th ed. InputsInputs toto M1M1 && premotorpremotor areasareas

Association cortex → premotor areas → M1 M1M1 vsvs PremotorPremotor areasareas

StimulationStimulation ofof M1M1 evokesevokes simplesimple movementsmovements ofof singlesingle jointsjoints StimulationStimulation ofof PMPM areasareas evokesevokes moremore complexcomplex movementsmovements involvinginvolving multiplemultiple jointsjoints andand resemblingresembling naturalnatural coordinatedcoordinated handhand shapingshaping oror reachingreaching movementsmovements Cingulate motor area (CMA) projects to facial motor neurons innervating superior facial muscles

M1 (inferior face) is supplied by MCA CMA is supplied by ACA

Purves, et al, Neuroscience, 3rd ed. PyramidalPyramidal systemsystem

CorticospinalCorticospinal tractstracts CorticobulbarCorticobulbar tractstracts ExtrapyramidalExtrapyramidal systemsystem

BrainBrain stemstem pathwayspathways RubrospinalRubrospinal VestibulospinalVestibulospinal ReticulospinalReticulospinal TectospinalTectospinal BasalBasal gangliaganglia loopsloops CerebellarCerebellar loopsloops SpinocerebellumSpinocerebellum VestibulocerebellumVestibulocerebellum Pyramidal & extrapyramidal pathways

UpperUpper MotorMotor NeuronNeuron UMNUMNUMN

BASAL CEREBELLUMCEREBELLUM BASAL GANGLIAGANGLIA

LowerLower MotorMotor NeuronNeuron lower motor neuron LMNLMNLMN SSequenceequence ofof eventsevents inin thethe controlcontrol ofof postureposture andand movementmovement MotorMotor controlcontrol integrationintegration OculomotorOculomotor systemsystem

The eye movements of a subject viewing a picture of Queen Nefertiti (over 2 min. time) TheThe importanceimportance ofof thethe gazegaze systemsystem arisesarises fromfrom thethe anatomyanatomy ofof thethe eyeeye

We see best with the fovea, the specialized area at the center of the retina that detects a tiny fraction of the visual field When we want to examine an object in the world, we have to move the fovea to it → this is done by 2 systems oculomotor system - moves the eyes in the orbit head movement system - moves the orbits in space EyeEye isis capablecapable ofof movementmovement inin 33 axesaxes

Horizontally Abduction Adduction Vertically Elevation Depression Diagonally Intorsion Extorsion Results in 9 cardinal points of gaze ExtraocularExtraocular MusclesMuscles (EOM)(EOM)

SixSix pairspairs ofof striatedstriated Sup. oblique musclesmuscles produceproduce thethe eyeeye movementsmovements Sup. rectus Medial rectus Lateral rectus Superior rectus Inferior rectus Med. rectus Lat. rectus Superior oblique Inferior oblique Inf. rectus Inf. oblique InnervationInnervation andand movementsmovements ofof extraocularextraocular musclesmuscles

Because the muscles attach to a globe which changes location within the orbit, few muscles have only one line of pull Line of pull varies with position of eye Muscle will be the prime mover for one direction and assist with movement in 2 -3 other directions ExtraocularExtraocular musclesmuscles areare controlledcontrolled byby 33 cranialcranial nervesnerves

OculomotorOculomotor NerveNerve -- CNCN IIIIII TrochlearTrochlear NerveNerve -- CNCN IVIV AbducensAbducens NerveNerve -- CNCN VIVI OculomotorOculomotor nervenerve (CN(CN III)III)

InnervatesInnervates 55 musclesmuscles Medial, superior, inferior rectus muscles, inferior oblique PrimaryPrimary lineline ofof pullpull Elevation and depression (vertical eye movement) AlsoAlso contributescontributes toto Sup. oblique Adduction (convergence) Sup. rectus Extorsion (down and out)

Med. rectus Lat. rectus

Inf. rectus Inf. oblique OculomotorOculomotor nervenerve (CN(CN III)III)

ControlsControls levatorlevator palpebraepalpebrae superiorissuperioris Elevates eyelid as eyes move vertically HasHas secondsecond motormotor nucleusnucleus calledcalled thethe EdingerEdinger --WestphalWestphal nucleusnucleus Controls internal musculature of eye ciliary muscle (lens) sphincter muscle (pupil) Parasympathetic innervation pupillary constriction through sphincter muscle thickening of lens through ciliary muscle CNCN IIIIII –– motormotor && EdingerEdinger --WestphalWestphal nucleusnucleus

E-W

motor OculomotorOculomotor nervenerve (CN(CN III)III)

BecauseBecause itit controlscontrols internalinternal musculaturemusculature ofof eyeeye andand adductionadduction itit alsoalso controlscontrols accommodationaccommodation 3-step process used to keep images in focus as they come near the face convergence (adduction) pupillary constriction thickening of lens HasHas 22 branchesbranches One innervates superior rectus and levator palpebrae Other innervates medial and inferior rectus, inferior oblique and internal musculature TrochlearTrochlear nervenerve (CN(CN IV)IV)

InnervatesInnervates superiorsuperior obliqueoblique pulley On the contralateral side Sup. oblique Only CN to innervate contralateral muscle Sup. rectus BecauseBecause musclemuscle tendontendon ofof

superiorsuperior obliqueoblique goesgoes Lat. rectus throughthrough aa pulley,pulley, lineline ofof pullpull Med. rectus ofof thethe musclemuscle isis diagonaldiagonal Inf. rectus Primary line of pull is intorsion Inf. oblique (up and in) Superior oblique muscle tendon going But also moves eye down and through pulley (trochlea) changing its out line of pull CNCN IVIV -- mostmost vulnerablevulnerable toto traumatrauma ofof thethe 33 nervesnerves

CNCN IVIV isis vulnerablevulnerable toto injuryinjury fromfrom eveneven mildmild headhead traumatrauma becausebecause thethe axonsaxons ofof thethe nervesnerves exitexit fromfrom thethe rearrear ofof thethe midbrain,midbrain, crosscross eacheach otherother andand traveltravel toto thethe ventralventral brainstembrainstem beforebefore exiting.exiting. BilateralBilateral injuryinjury cancan occuroccur atat thethe juncturejuncture ofof theirtheir crossing.crossing. Axons of CN IV coming from the dorsal midbrain to the ventral AbducensAbducens NerveNerve (CN(CN VI)VI)

InnervatesInnervates laterallateral rectusrectus musclemuscle StraightStraight lineline ofof pullpull abductsabducts eyeeye Sup. oblique

Sup. rectus

Med. rectus Lat. rectus

Inf. rectus Inf. oblique The contributions of the 6 extraocular muscles to vertical and horizontal eye movements 55 movementmovement systemssystems putput thethe foveafovea onon aa targettarget andand keepkeep itit therethere

3 systems keep the fovea on a visual target Saccadic eye movements shift the fovea rapidly to a visual target in the periphery Smooth pursuit movements keep the image of a moving target on the fovea Vergence movements move the eyes in opposite directions so that the image is positioned on both foveae 2 systems stabilize the eye during head movement Vestibulo -ocular movements hold images still on the retina during brief head movements (driven vestibular system ) Optokinetic movements hold images during sustained head rotation (driven by visual stimuli )

All 5 systems shares the same effector pathway - the 3 bilateral groups of oculomotor neurons in the brain stem TypesTypes ofof eyeeye movementmovement controlcontrol

The purpose of the saccade is to move the eyes as quickly as possible to a newly appeared target

Keeps the image of a moving target on the fovea by calculating how fast the target is moving and moving the eyes accordingly

Produce disconjugate movements ensur ing that the object of interest is on the same place in both retinas → sense of depth

Hold images still on the retina during brief head movements VergenceVergence eyeeye movementsmovements

ConvergenceConvergence Medial recti muscles contract to move eyes inward

DivergenceDivergence Lateral recti muscles move eyes back to parallel position - conjugate gaze DDirectionirection ofof eyeeye movementmovement isis controlledcontrolled byby thethe locallocal circuitcircuit neuronsneurons inin 22 gazegaze centerscenters inin thethe reticularreticular formationformation

Paramedian pontine reticular formation (PPRF ) → horizontal gaze center Rostral iMLF (rostral part of the midbrain reticular formation) → vertical gaze center

iMLF = interstitial nucleus of the medial longitudinal fasciculu s SynapticSynaptic circuitrycircuitry responsibleresponsible forfor horizontalhorizontal movementsmovements

Activation of local circuit neurons in the right horizontal gaze center (the PPRF; orange) leads to increased activity of lower motor neurons (red and green) and internuclear neurons (blue) in the right abducens nucleus. CCortexortex controlscontrols thethe saccadicsaccadic BA 8 systemsystem throughthrough thethe superiorsuperior colliculuscolliculus

FFrontalrontal eyeeye fieldfield

Superior colliculus

PPRFPPRF

Superior colliculus projects to both the PPRF (horizontal) and rostral iMLF (vertical ) gaze centers , providing the motor command to move the eye to an intended new position for the foveation of a visual stimulus. Basal ganglia loops – oculomotor loop

TheThe neuralneural activityactivity inin thethe substantiasubstantia nigranigra parspars reticulatareticulata maintainsmaintains thethe superiorsuperior colliculuscolliculus tonicallytonically inhibitedinhibited toto preventprevent unwantedunwanted saccades.saccades. PriorPrior toto aa voluntaryvoluntary saccade,saccade, thisthis tonictonic inhibitioninhibition isis reducedreduced byby inputsinputs fromfrom thethe caudate,caudate, whichwhich isis activatedactivated byby signalssignals formform thethe cortex.cortex. (-) Superior colliculus FrontalFrontal eyeeye fieldfield lesionlesion →→ contralateralcontralateral conjugateconjugate gazegaze paresisparesis

R L PPRFPPRF lesionlesion →→ ipsilateralipsilateral conjugateconjugate gazegaze paresisparesis

R L

PathwaysPathways forfor smoothsmooth pursuitpursuit eyeeye movementsmovements OculomotorOculomotor regionsregions ofof ccerebellumerebellum AAutonomicutonomic nervousnervous systemsystem (ANS)(ANS) -- thethe involuntaryinvoluntary motormotor systemsystem

SomaticSomatic motormotor neuronsneurons areare locatedlocated withinwithin CNSCNS AAutonomicutonomic motormotor neuronsneurons ((= postganglionicpostganglionic neurons)neurons) areare locatedlocated outsideoutside CNSCNS MainMain subdivisionssubdivisions ofof thethe ANSANS

SSympatheticympathetic nervousnervous systemsystem PParasympatheticarasympathetic nervousnervous systemsystem EEntericnteric nervousnervous systemsystem SympatheticSympathetic vsvs parasympatheticparasympathetic ANSANS ANSANS –– locationlocation ofof preganglionicpreganglionic neuronsneurons

SpinalSpinal CordCord -- IntermediolateralIntermediolateral cellcell columncolumn Sympathetic: T1 -L3 Parasympathetic: S2 -S4 BrainBrain StemStem -- ParasympatheticParasympathetic dorsal motor nucleus of Vagus – CN X inferior salivatory nucleus – CN IX superior salivatory nucleus – CN VII Edinger -Westphal nucleus – CN III ANSANS –– preganglionicpreganglionic sympatheticsympathetic neuronsneurons inin spinalspinal cordcord ANSANS –– preganglionicpreganglionic parasympatheticparasympathetic neuronsneurons inin spinalspinal corcordd ParasympatheticParasympathetic ANSANS -- CNCN XX

Solitarius Dorsal motor

Ambiguus ParasympatheticParasympathetic ANSANS -- CNCN IXIX

Solitarius Inferior salivatory

Ambiguus ParasympatheticParasympathetic ANSANS -- CNCN VIIVII

Solitarius Superiorsol salivatory

sal

Motor VII ParasympatheticParasympathetic ANSANS -- CNCN IIIIII

Edinger–Westphal

Motor TypesTypes ofof outflowoutflow inin ANSANS IInnervationnnervation ofof sympatheticsympathetic autonomicautonomic gangliaganglia

Preganglionic neurons - spinal cord Preganglionic axons exit the spinal cord through the ventral roots → enter ganglia via the spinal nerves and white communicating rami Post ganglionic neurons – paravertebral ganglia Post ganglionic axons exit via the gray communicating rami and spinal nerves NeurotransmittersNeurotransmitters ofof ANSANS

NE HYPOTHALAMUSHYPOTHALAMUS

Descending Autonomic Pathway

PreganglionicPreganglionic Neuron Neuron

ParasympatheticParasympathetic Sympathetic Sympathetic AUTONOMICAUTONOMIC Ach Ach MOTORMOTOR SYSTEMSYSTEM IntramuralIntramural ganglia ganglia Paravertebral Paravertebral ganglia ganglia CranialCranial ganglia ganglia Prevertebral Prevertebralganglia ganglia

PostganglionicPostganglionic Neuron Neuron

Ach NE

Effectors:Effectors: SmoothSmooth MuscleMuscle && GlandGland IntracranialIntracranial sympatheticsympathetic fibersfibers areare derivedderived fromfrom cervicalcervical sympatheticsympathetic trunktrunk

Horner’s syndrome AutonomicAutonomic innervationinnervation ofof thethe heartheart andand lungslungs Abdominal sympathetic plexuses

(3) Nn. splanchnici thoracici

(12)

Nn. splanchnici lumbales

(4)

Nn. splanchnici sacrales (1) Nn. splanchnici pelvici SympatheticSympathetic vsvs parasympatheticparasympathetic effectseffects

Sympathetic Parasympathetic

Cardiovascular system blood vessels none to skeletal muscle vasodilation to skin and viscera vasoconstriction Heart rate, force of contraction increases decreases Respiratory system diameter of air passages increases decreases respiratory rate increases decreases Eye dilate pupil constrict pupil accommodation distance vision near vision Sweat gland increased secretion none Adrenal gland secretes E, NE none SympatheticSympathetic vsvs parasympatheticparasympathetic effectseffects

Sympathetic Parasympathetic

Digestive system general level of activity decreases increases sphincters constrict dilate secretory glands inhibit stimulate salivary gland stimulate simulate serous secretion watery secretion Urinary system kidneys decreases urine increases urine urinary bladder relaxes tenses sphincter constricts relaxes Male reproductive system increases erection glandular secretion and ejaculation Sympathetic Parasympathetic - fight of flight reaction - energy conservation for emergency situation • increases blood supply to skeletal muscle • increases general activity of • increases heart rate digestive system • increases diameter of • increases secretion of air passages digestive glands • increases rate of respiration • increases urine production • dilate pupil and relaxes sphincter • secrets epinephrine and • erection norepinephrine • decreases diameter of • decreases blood to viscera air passages • constricts bladder sphincter • decreases respiratory rate • constricts pupil • increases sweat production • constrict arrector pili muscle Sympathetic ↑

Parasympathetic ↑ Functions of sympathetic NS Functions of parasympathetic NS AUTONOMICAUTONOMIC MOTORMOTOR SYSTEMSYSTEM

Descending PreganglionicPreganglionic NeuronNeuron HYPOTHALAMUSHYPOTHALAMUS Autonomic Pathway

Preganglionic Fiber

PostganglionicPostganglionic NeuronNeuron Ach Postganglionic fiber

Ach & NE SmoothSmooth MuscleMuscle && GlandGland

EntericEnteric nnervouservous ssystemystem (ENS)(ENS) isis llargelyargely aautonomousutonomous

ContainsContains 8080 --100100 millionmillion neuronsneurons ((approxapprox .. = spinalspinal cordcord )) CellCell bodiesbodies ofof neuronsneurons areare groupedgrouped inin 22 majormajor plexusesplexuses MMyentericyenteric (Auerbach's)(Auerbach's) →→ gutgut motilitymotility SSubmucousubmucous (Meissner's)(Meissner's) →→ gutgut secretionssecretions AsAs inin thethe CNS,CNS, sensorysensory neurons,neurons, interneurons,interneurons, andand motormotor neuronsneurons inin thethe ENSENS areare connectedconnected synapticallysynaptically forfor thethe flowflow ofof informationinformation TheThe motormotor neuronneuron poolpool ofof thethe ENSENS consistsconsists ofof bothboth excitatoryexcitatory andand inhibitoryinhibitory neuronsneurons AA hierarchyhierarchy ofof 55 levelslevels ofof neuralneural organizationorganization determinesdetermines thethe momentmoment --toto --momentmoment motormotor behaviorbehavior ofof thethe digestivedigestive tracttract