CHAPTER 18The Brain and the Cranial Nerves

Copyright © 2007 by John Wiley & Sons, Inc.

Principles ofHuman Anatomy

Eleventh EditionGerard J. Tortora

&

Mark T. Nielsen

Major Brain AreasMajor Brain Areas

19_01b19_01b Cerebrospinal FluidCerebrospinal Fluid FunctionsFunctions

Mechanical protectionMechanical protection Chemical protectionChemical protection CirculationCirculation

Formed by:Formed by: EpendymalEpendymal cells of the Choroid Plexusescells of the Choroid Plexuses

Flow from the choroid plexuses to the Flow from the choroid plexuses to the arachnoidarachnoidvillavilla

CircumventricularCircumventricular organsorgans HypothalamusHypothalamus PitutaryPitutary Pineal gland (body)Pineal gland (body)

Brain VentriclesBrain Ventricles

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Brain StemBrain Stem

Medulla oblongataMedulla oblongata Ascending sensory & descending motor tractsAscending sensory & descending motor tracts Cross over at Cross over at decussationdecussation of pyramidsof pyramids MedullaryMedullary rhythmicityrhythmicity area (basic breathing rhythm)area (basic breathing rhythm) Complex reflexive behaviorsComplex reflexive behaviors

PonsPons PneumotaxicPneumotaxic and and apneusticapneustic areas (breathing reg.)areas (breathing reg.) Reticular formation (RAS)Reticular formation (RAS)

Sleep & wake cyclesSleep & wake cycles

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CerebellumCerebellum

White matter White matter –– Arbor vitaeArbor vitae The tree of lifeThe tree of life

Coordinates complex motor sequencesCoordinates complex motor sequences

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19_08d19_08d HypothalamusHypothalamus

ANSANS Pituitary glandPituitary gland Emotional & behavioral patternsEmotional & behavioral patterns Eating and drinkingEating and drinking Body temperatureBody temperature Diurnal rhythmsDiurnal rhythms

HypothalamusHypothalamus CerebrumCerebrum Cerebral cortex Cerebral cortex –– rolls and foldsrolls and folds

Rolls Rolls -- GyriGyri Deep folds Deep folds –– fissures fissures

E.g. Longitudinal fissureE.g. Longitudinal fissure Shallow folds or grooves Shallow folds or grooves –– sulcisulci

E.g. Central E.g. Central sulcussulcus

LobesLobes Frontal, Parietal, Occipital, TemporalFrontal, Parietal, Occipital, Temporal

19_11ab19_11ab White matter in the cerebrumWhite matter in the cerebrum

MyelinatedMyelinated axon tracts that extend in 3 axon tracts that extend in 3 directionsdirections Association fibersAssociation fibers –– connect connect gyrigyri w/in a w/in a

hemispherehemisphere Commissural fibersCommissural fibers –– connect connect gyrigyri of one of one

hemisphere to the opposite hemisphere to the opposite gyrigyri in the other in the other hemispherehemisphere

Projection fibersProjection fibers –– ascending & descending ascending & descending tracts connecting the cerebrum with other tracts connecting the cerebrum with other brain parts and spinal cordbrain parts and spinal cord

White Matter TractsWhite Matter Tracts Functional areas of the cortexFunctional areas of the cortex

Sensory Sensory –– receive informationreceive information Motor Motor –– control of muscular control of muscular

movementsmovements Association Association –– complex integrative complex integrative

functionsfunctionsMemory, emotion, reason, personality Memory, emotion, reason, personality

intelligenceintelligence

Functional areas of the cortexFunctional areas of the cortex

Sensory areasSensory areas Primary Primary somatosensorysomatosensory cortexcortexPostPost--central central gyrusgyrus

Touch, Touch, proprioceptionproprioception, pain, temperature, pain, temperature

Entire body represented, but not equallyEntire body represented, but not equallyLips and fingers Lips and fingers –– larger area devotedlarger area devoted

Functional Areas of CortexFunctional Areas of Cortex

21_0521_05 Functional Areas of CortexFunctional Areas of Cortex

Primary Motor CortexPrimary Motor CortexPrePre--central central gyrusgyrusVoluntary contractions of motor Voluntary contractions of motor groupsgroups

Muscles represented, but not equallyMuscles represented, but not equally Large area for vocalization and handsLarge area for vocalization and hands

Functional Areas of CortexFunctional Areas of Cortex 21_0521_05

Functional Areas of CortexFunctional Areas of Cortex

Primary visual cortexPrimary visual cortex Medial surface of occipital lobeMedial surface of occipital lobe

Primary auditory area Primary auditory area Temporal lobeTemporal lobe

Auditory association areaAuditory association area WernickeWernicke’’ss area area –– usually in the left usually in the left

hemispherehemisphere Motor speech areaMotor speech area

BrocaBroca’’ss area area –– usually in the left hemisphereusually in the left hemisphere

Functional Areas of CortexFunctional Areas of Cortex

Brain LateralizationBrain Lateralization Split BrainsSplit Brains

See a star with the right eyeSee a star with the right eyeCan tell you they saw a starCan tell you they saw a star

See a star with the left eyeSee a star with the left eyeCannot tell you what they sawCannot tell you what they sawCan point to itCan point to itBut only with their left handBut only with their left hand

Cranial NervesCranial Nerves11Oh, Oh, 22Oh, Oh, 33Oh, Oh, 44To, To, 55Touch, Touch, 66And, And,

77Feel, Feel, 88Very, Very, 99Grotesque, Grotesque, 1010Visera, Visera, 1111AA1212Hhhhh!!Hhhhh!!

11Olfactory, Olfactory, 22Optic, Optic, 33Occulomotor, Occulomotor, 44Trochlear, Trochlear, 55Trigeminal, Trigeminal, 66Abducens, Abducens, 77Facial, Facial, 88Vestibulocochlear, Vestibulocochlear, 99Glossopharyngeal, Glossopharyngeal, 1010Vagus, Vagus, 1111Accessory, Accessory, 1212HypoglossalHypoglossal

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19_07a19_07a Learning Objectives

Discuss the importance of a choriodplexus

Describe a circumventricular organ and give examples

What are some of the functions of the following: medulla oblongata, pons, cerebellum, hypothalamus, decussation of pyramids

Learning Objectives

Discuss the components of the brain stem Discuss the components of the

diencephalon What is the arbor vitae Discuss the functional areas of the cortex Why are Broca’s and Wernicke’s areas

important? Discuss brain lateralization

Learning Objectives

Discuss association commissural and projection fibers in the cerebrum

Describe the corpus callosum Compare white vs. gray matter Discuss how a split brain individual reacts

to visual cues Memorize the cranial nerve names and

functions