Organization and Functions of the Nervous System

Organization and Functions Organization and Functions of the Nervous Systemof the Nervous System

Nervous System DivisionsNervous System Divisions

CNS (central nervous CNS (central nervous system)system) Brain, Spinal Cord Brain, Spinal Cord 12 pairs of cranial nerves 12 pairs of cranial nerves

(originate from cranium)(originate from cranium)

PNS (peripheral nervous PNS (peripheral nervous system)system) Somatic nervous systemSomatic nervous system

31 pairs of spinal nerves31 pairs of spinal nerves Autonomic nervous systemAutonomic nervous system

Afferent and Efferent Afferent and Efferent NervesNerves

12 cranial nerves12 cranial nerves

Autonomic Nervous SystemAutonomic Nervous System

Autonomic Nervous SystemAutonomic Nervous SystemSympathetic DivisionSympathetic Division

Exits Thoracic-Lumbar region of Exits Thoracic-Lumbar region of SCSC

Norepinephrine in postganglionic Norepinephrine in postganglionic synapsessynapses

Fight-or-Flight ResponseFight-or-Flight ResponseElevated hr, bpElevated hr, bpPupil dilationPupil dilationIncreased sweat gland activityIncreased sweat gland activityDry mouthDry mouthIncreased blood flow to Increased blood flow to musclesmuscles

Parasympathetic DivisionParasympathetic Division Exits Cranial and Sacral Exits Cranial and Sacral

regions of SCregions of SC Acetylcholine in Acetylcholine in

postganglionic synapsespostganglionic synapses Energy ConservationEnergy Conservation

Decreased hr, bpDecreased hr, bpPupil constrictionPupil constrictionSalivationSalivationGastric SecretionGastric Secretion

Protection of the CNSProtection of the CNS

Meninges (3 protective layers)Meninges (3 protective layers) Dura MaterDura Mater Arachnoid MembraneArachnoid Membrane Pia MaterPia Mater

Cerebrospinal Fluid Cerebrospinal Fluid Buoyancy and Shock AbsorptionBuoyancy and Shock Absorption Ventricles and subarachnoid spaceVentricles and subarachnoid space

Ventricular SystemVentricular System

Dissection PlanesDissection Planes

NeuroanatomyNeuroanatomyDirectional TerminologyDirectional Terminology

Anterior – Posterior (Front –Back)Anterior – Posterior (Front –Back)

Dorsal – Ventral (Top – Bottom)Dorsal – Ventral (Top – Bottom)

Medial – Lateral (Middle –Side)Medial – Lateral (Middle –Side)

Superior –Inferior (Above – Below)Superior –Inferior (Above – Below)

Spinal CordSpinal Cord

Brain DivisionsBrain Divisions

Four Cerebral LobesFour Cerebral Lobes

Midsagittal View of BrainMidsagittal View of Brain

Ventral Surface of BrainVentral Surface of Brain

Cerebral CortexCerebral Cortex

Basal GangliaBasal Ganglia

Three Main ComponentsThree Main Components Caudate NucleusCaudate Nucleus PutamenPutamen Globus PallidusGlobus Pallidus

Major FunctionsMajor Functions Motor ControlMotor Control Somatosensory-Motor Somatosensory-Motor

IntegrationIntegration

Diseases of the BGDiseases of the BG Parkinson’s DiseaseParkinson’s Disease Huntington’s DiseaseHuntington’s Disease

Limbic SystemLimbic SystemLimbic Structures: a group of structures surrounding Limbic Structures: a group of structures surrounding the brain stemthe brain stem Cingulate CortexCingulate Cortex HippocampusHippocampus AmygdalaAmygdala Mammillary BodiesMammillary Bodies Anterior HypothalamusAnterior Hypothalamus FornixFornix

FunctionsFunctions EmotionsEmotions MemoryMemory

DiencephalonDiencephalonThalamusThalamus

Two lobes at the anterior portion of the brain stem surrounding Two lobes at the anterior portion of the brain stem surrounding the third ventricle, joined by massa intermediathe third ventricle, joined by massa intermedia

Interconnected with Cerebral Cortex and with CerebellumInterconnected with Cerebral Cortex and with Cerebellum Major Sensory RelayMajor Sensory Relay

Vision: Lateral Geniculate NucleusVision: Lateral Geniculate NucleusHearing: Medial Geniculate NucleusHearing: Medial Geniculate NucleusTouch: Ventral Posterior NucleusTouch: Ventral Posterior NucleusSmell: Medial Dorsal NucleusSmell: Medial Dorsal NucleusTaste: Ventral Posterior NucleusTaste: Ventral Posterior Nucleus

DiencephalonDiencephalonHypothalamusHypothalamus Located below the anterior thalamusLocated below the anterior thalamus Contains several subdivisions and interconnected Contains several subdivisions and interconnected

with limbic system regionswith limbic system regions Detection of need states, involved in hormone and Detection of need states, involved in hormone and

temperature, fluid & nutrient regulationtemperature, fluid & nutrient regulation

Brain StemBrain StemBrain StemBrain Stem—midbrain + hindbrain —midbrain + hindbrain (minus the cerebellum)(minus the cerebellum)

Tectum (“roof”) Tectum (“roof”) relays visual and auditory information and relays visual and auditory information and

controls simple reflexes, eye and ear controls simple reflexes, eye and ear orientation movementsorientation movements

superior colliculi (“little hills”)—relay visual superior colliculi (“little hills”)—relay visual informationinformation

inferior colliculi—relay auditory informationinferior colliculi—relay auditory information

Mesencephalon (Midbrain)Mesencephalon (Midbrain)

Mesencephalon (Midbrain)Mesencephalon (Midbrain)

Tegmentum (“floor covering”) Tegmentum (“floor covering”) Substantia nigra—integration of Substantia nigra—integration of

voluntary movementsvoluntary movements Red nucleus—controls basic body Red nucleus—controls basic body

movementsmovements Reticular formation—controls arousal Reticular formation—controls arousal

and consciousnessand consciousness RaphRaphéé system system

The HindbrainThe Hindbrain

The HindbrainThe HindbrainMetencephalon Metencephalon Pons—a “bridge” for many fibers passing from Pons—a “bridge” for many fibers passing from

one side of the brain to the other. one side of the brain to the other. Contains sensory fibers, fibers from the cortex to Contains sensory fibers, fibers from the cortex to cerebellum, and fibers that relay information on cerebellum, and fibers that relay information on sleep, arousal, muscle tone, and dreaming. sleep, arousal, muscle tone, and dreaming.

Cerebellum—involved in the development and Cerebellum—involved in the development and coordination of movementcoordination of movement

Myelencephalon Medulla Oblongata Medulla Oblongata

Cranial nerve nucleiCranial nerve nucleiRegulates basic life functions (e.g., respiration, heart Regulates basic life functions (e.g., respiration, heart rate, vomiting, salivation)rate, vomiting, salivation)

CerebellumCerebellum

ComponentsComponents VermisVermis Lateral zoneLateral zone Flocculonodular lobeFlocculonodular lobe

Cell LayersCell Layers Molecular LayerMolecular Layer Purkinje Cell LayerPurkinje Cell Layer Granule Cell LayerGranule Cell Layer

Major FunctionsMajor Functions BalanceBalance Motor CoordinationMotor Coordination Timing and sequencing of Timing and sequencing of

rapid movementsrapid movements Sensorimotor LearningSensorimotor Learning Cognition?Cognition?