The Brain and The Brain and Cranial NervesCranial Nerves

The BrainThe Brain– IntroductionIntroduction– Development of brainDevelopment of brain

EmbryologyEmbryology

– Anatomy of brainAnatomy of brain Parts and functionsParts and functions

The BrainThe Brain

Introduction to the BrainIntroduction to the Brain– Weighs about 3 lbs. in adultsWeighs about 3 lbs. in adults– StructuresStructures

Divided into 3 general areasDivided into 3 general areas

– FunctionsFunctions Controls the bare necessities of lifeControls the bare necessities of life Location for primal drives and emotionsLocation for primal drives and emotions Intellectual thought, imagination, perception, Intellectual thought, imagination, perception,

interpretation, etc.interpretation, etc.

Human DevelopmentHuman Development– First two weeks – neural tube forms First two weeks – neural tube forms – 44thth week - anterior end of the neural tube forms week - anterior end of the neural tube forms

thethe forebrainforebrain midbrainmidbrain hindbrainhindbrain

Embryology – 3-4 WeeksEmbryology – 3-4 Weeks

Embryology – 4 WeeksEmbryology – 4 Weeks

Embryology – 5 WeeksEmbryology – 5 Weeks

Embryology – 11 WeeksEmbryology – 11 Weeks

A Child’s BrainA Child’s Brain

Adult BrainAdult Brain– Forebrain Forebrain

CerebrumCerebrum Thalamus & hypothalamus Thalamus & hypothalamus

– Midbrain Midbrain – Hindbrain Hindbrain

Cerebellum & ponsCerebellum & pons Medulla oblongataMedulla oblongata

Adult BrainAdult Brain

Protections and CoveringsProtections and Coverings– Cranial bones – strong supportCranial bones – strong support– Cranial meninges – shock absorbersCranial meninges – shock absorbers

Dura mater Dura mater ArachnoidArachnoid Pia materPia mater

The Cranial MeningesThe Cranial Meninges

The Ventricles of the BrainThe Ventricles of the Brain– Hollow areas within the brainHollow areas within the brain

Connect to spinal canal and space around the brainConnect to spinal canal and space around the brain

– Cerebrospinal fluid circulates around the brain, Cerebrospinal fluid circulates around the brain, down through the ventricles, and into the spinal down through the ventricles, and into the spinal cord.cord.

Ventricles of the BrainVentricles of the Brain

Ventricles of the BrainVentricles of the Brain

Cerebrospinal FluidCerebrospinal Fluid– CompositionComposition

Clear, colorless, wateryClear, colorless, watery Contains proteins, glucose, urea, saltsContains proteins, glucose, urea, salts Contains white blood cellsContains white blood cells

– FunctionsFunctions ““Floats” the brainFloats” the brain Medium of transportMedium of transport

Circulation of Circulation of Cerebrospinal FluidCerebrospinal Fluid

Problems Associated with Problems Associated with CSFCSF

– HydrocephalusHydrocephalus– MeningitisMeningitis– HeadachesHeadaches

HydrocephalusHydrocephalus

Blood-Brain BarrierBlood-Brain Barrier– A function of glial cells A function of glial cells

Secrete chemicals that maintain the BBBSecrete chemicals that maintain the BBB Absorb materials from bloodAbsorb materials from blood Extract materials from brainExtract materials from brain

– Cells of capillaries form tight junctionsCells of capillaries form tight junctions– Differential rates of passage of certain materialsDifferential rates of passage of certain materials

Blood-Brain BarrierBlood-Brain Barrier

The Parts of the The Parts of the BrainBrainForebrainForebrain

Cerebrum, Cerebrum, Hypothalamus, ThalamusHypothalamus, Thalamus

Cerebrum – Gray & White Cerebrum – Gray & White MatterMatter

– Outer layer – cerebral cortexOuter layer – cerebral cortex Gray matterGray matter

– Inner portionInner portion White matterWhite matter Masses of gray matter – cerebral nucleiMasses of gray matter – cerebral nuclei

Cerebrum – Gray & White Cerebrum – Gray & White MatterMatter

Cerebral CortexCerebral Cortex– Gyri are separated by grooves (sulci)Gyri are separated by grooves (sulci)

Fissures – deeper groovesFissures – deeper grooves

– Divided into cerebral hemispheresDivided into cerebral hemispheres

Gyri & SulciGyri & Sulci

Cerebral CortexCerebral Cortex– Divided into lobesDivided into lobes– Well mappedWell mapped

Decision-making, planning, personalityDecision-making, planning, personality Primary motor cortexPrimary motor cortex Primary sensory cortexPrimary sensory cortex

Cerebral LobesCerebral Lobes

HomunculusHomunculus

Primary Motor Cortex Primary Sensory Cortex

Cerebral NucleiCerebral Nuclei– Collections of cell bodies (gray matter)Collections of cell bodies (gray matter)– Mostly control the movement of skeletal Mostly control the movement of skeletal

musclesmuscles

Cerebral NucleiCerebral Nuclei

Limbic SystemLimbic System– Functional unit (not anatomical)Functional unit (not anatomical)– Emotional part of the brainEmotional part of the brain

Feelings of fear, loss, love, rage, etc.Feelings of fear, loss, love, rage, etc.

– Includes parts of several anatomical structuresIncludes parts of several anatomical structures CerebrumCerebrum HypothalamusHypothalamus ThalamusThalamus

Limbic SystemLimbic System

HypothalamusHypothalamus– Initiates primal drives Initiates primal drives

Hunger, thirst, sex, rage, etc. Hunger, thirst, sex, rage, etc. Controls autonomic nervous systemControls autonomic nervous system

– ““fight or flight” sympathetic response.fight or flight” sympathetic response.

– Controls pituitary gland (“master gland” of Controls pituitary gland (“master gland” of endocrine system)endocrine system) Infundibulum (“funnel”) funnels secretions to the Infundibulum (“funnel”) funnels secretions to the

pituitary glandpituitary gland

HypothalamusHypothalamus– Location – under thalamusLocation – under thalamus– StructureStructure

Clusters of nerve cell bodiesClusters of nerve cell bodies– Autonomic centersAutonomic centers

InfundibulumInfundibulum

HypothalamusHypothalamus

ThalamusThalamus– Functions as a relay station between the body Functions as a relay station between the body

and the cerebral cortexand the cerebral cortex Inform us of our emotional stateInform us of our emotional state Relay information concerned with motor Relay information concerned with motor

requirements & actionsrequirements & actions Integrate visual and auditory reflexesIntegrate visual and auditory reflexes

The ThalamusThe Thalamus

ThalamusThalamus

EpithalamusEpithalamus– LocationLocation

Above thalamusAbove thalamus

– Contains the pineal bodyContains the pineal body Secretes melatoninSecretes melatonin

MidbrainMidbrain

Midbrain Midbrain – Relay stationRelay station– Tracts of motor and sensory neuronsTracts of motor and sensory neurons– Contains nucleiContains nuclei

Substantia nigra secretes dopamineSubstantia nigra secretes dopamine– Modifies muscle tone & motor activityModifies muscle tone & motor activity– Parkinson’s disease Parkinson’s disease

MidbrainMidbrain

HindbrainHindbrainCerebellum, Pons, & Cerebellum, Pons, & Medulla OblongataMedulla Oblongata

CerebellumCerebellum– 22ndnd largest structure of the brain largest structure of the brain– Divided into 2 lateral hemispheresDivided into 2 lateral hemispheres– Cortex – gyri & sulciCortex – gyri & sulci

Gray matterGray matter

– InteriorInterior White matterWhite matter

– Cerebellar nuclei – deep within white matter Cerebellar nuclei – deep within white matter Gray matterGray matter

CerebellumCerebellum– Functions – controls subconscious movements Functions – controls subconscious movements

in skeletal musclein skeletal muscle CoordinationCoordination PosturePosture BalanceBalance

Cerebellum, Pons, Medulla Cerebellum, Pons, Medulla OblongataOblongata

PonsPons– Pons = “bridge”Pons = “bridge”

Connects the spinal cord with the brain and parts of Connects the spinal cord with the brain and parts of the brain with each otherthe brain with each other

Consists mostly of white fibersConsists mostly of white fibers

– FunctionsFunctions Controls respiration rate (with medulla)Controls respiration rate (with medulla)

Medulla OblongataMedulla Oblongata– Continuation of spinal cordContinuation of spinal cord– FunctionsFunctions

Maintains wakefulness and alertnessMaintains wakefulness and alertness Contains reflex centersContains reflex centers

– Cardiac center, vasomotor center, respiratory rythmicity Cardiac center, vasomotor center, respiratory rythmicity centercenter

– Other nonvital centers Other nonvital centers

Medulla OblongataMedulla Oblongata

Cranial NervesCranial Nerves

Introduction to Cranial Introduction to Cranial NervesNerves

– 12 pairs12 pairs– Leave the skull through foraminaLeave the skull through foramina– TypesTypes

MixedMixed SensorySensory MotorMotor

– Part of the somatic nervous systemPart of the somatic nervous system– Innervate organs in head, neck and upper Innervate organs in head, neck and upper

thoraxthorax

The Cranial NervesThe Cranial Nerves