It is the source of the It is the source of the Central nervous systemCentral nervous system.. It is derived fromIt is derived from::

EctodermEctoderm which is which is Differentiated in theDifferentiated in the 22ndnd WeekWeek..

Neural PlateNeural Plate: : A Dorsal Midline A Dorsal Midline

Thickening of the Thickening of the Ectoderm overlying the Ectoderm overlying the NotochordNotochord..

Neural FoldsNeural Folds: : Elevated Lateral Margins Elevated Lateral Margins

of the Neural Plateof the Neural Plate..They are on each side ofThey are on each side of

Neural GrooveNeural Groove (Longitudinal Midline (Longitudinal Midline Groove)Groove)..

Neural TubeNeural Tube:: AppositionApposition and and Fusion Fusion

of the Neural Foldsof the Neural Folds . .They seal the Neural They seal the Neural

Groove and Create the Groove and Create the TubeTube..

Growth of the Neural tube Growth of the Neural tube is is Maximal Maximal at the at the Cranial Cranial PartPart..

It becomes the It becomes the BrainBrain..The The Caudal Caudal Part becomesPart becomes::

Spinal CordSpinal Cord..NeuroaxisNeuroaxis: :

Axis of the tube is Axis of the tube is StraightStraight..

Central Cavity within Central Cavity within the Neural Tubethe Neural Tube..

Differentiates intoDifferentiates into::VentriclesVentricles of the of the

BrainBrain..Central CanalCentral Canal of the of the

Spinal CordSpinal Cord..

Separated Cells from the Separated Cells from the Apices of the Neural FoldsApices of the Neural Folds..

PositionPosition:: Dorsolateral to the Neural Dorsolateral to the Neural

TubeTube..Give rise toGive rise to: :

11 . .Autonomic GangliaAutonomic Ganglia..22 . .Sensory Ganglia of Sensory Ganglia of

Spinal and Cranial nervesSpinal and Cranial nerves..33 . .MelanocytesMelanocytes..

44 . .Cells of Suprarenal Cells of Suprarenal MedullaMedulla..

Grey matter:Grey matter: Located Centrally Located Centrally around the Central around the Central CanalCanal..

White matterWhite matter:: Forms the Outer Forms the Outer

CoatCoat..

A longitudinal Groove A longitudinal Groove along the Inner surface of along the Inner surface of the Lateral Walls of thethe Lateral Walls of the developing Spinal Corddeveloping Spinal Cord..

It differentiates the Gray It differentiates the Gray Matter intoMatter into::

Dorsal (Alar) plateDorsal (Alar) plate..It is predominantly It is predominantly

SSensoryensory.. Ventral (Basal) plateVentral (Basal) plate..

It is predominantly It is predominantly MotorMotor..

ThreeThree Primary Brain Primary Brain Vesicles appearVesicles appear . .

Fore BrainFore Brain ((ProsencephalonProsencephalon))..

Mid BrainMid Brain ((MesencephalonMesencephalon))..

Hind BrainHind Brain ((RombencephalonRombencephalon))..

Bending of the Bending of the Neuraxis is by Neuraxis is by Two Two FLexuresFLexures: :

CephalicCephalic ( Mid( Mid brain)brain) FlexureFlexure::

At the junction of the At the junction of the Fore and Mid BrainsFore and Mid Brains..

Cervical FlexureCervical Flexure: : Between the Brain Between the Brain

and Spinal Cordand Spinal Cord..

FiveFive Secondary Brain Secondary Brain Vesicles appearVesicles appear . .

Formed by Division ofFormed by Division ofProsencephalon intoProsencephalon into::

TelencephalonTelencephalon..DiencephalonDiencephalon..

Largest Brain VesicleLargest Brain Vesicle..Has the Greatest Has the Greatest

Degree of DevelopmentDegree of Development..FormsForms::

The Cerebral The Cerebral HemispheresHemispheres..

ThalamusThalamus is its Main is its Main PartPart..

It is connected to It is connected to the Cerebral Cortexthe Cerebral Cortex..

Differntiated intoDifferntiated into: : MetencephalonMetencephalon..MylencephalonMylencephalon..

The Third FlexureThe Third Flexure.. Appears between:Appears between:

MetencephalonMetencephalon and and MyelencephalonMyelencephalon..

MetencephalonMetencephalon::PonsPons. .

CerebellumCerebellum..MyelencephalonMyelencephalon::

Medulla OblongataMedulla Oblongata..

RemainRemains s UndifferentiatedUndifferentiated..

It keeps the It keeps the Embryonic PictureEmbryonic Picture: :

Grey Matter Grey Matter surrounds the Central surrounds the Central canalcanal..

((11 ) )Bilateral pairedBilateral paired For the senses ofFor the senses of: :

SmellSmell.. VisionVision..

HearingHearing.. ((22 ) )A symmetrical A symmetrical

midlinemidline:: VestibularVestibular centercenter

For the For the maintenance of maintenance of EquilibriumEquilibrium..

They are Expansions They are Expansions fromfrom::

Dorsal AspectDorsal Aspect of the of the simple Tubular Brainsimple Tubular Brain..

Composed ofComposed of: : Outer Cortex of Outer Cortex of NerveNerve

CellsCells.. Underlying Core of Underlying Core of

Nerve FibersNerve Fibers..

Centers for Centers for Vision Vision and and HearingHearing will have will have Automatic Reflex Automatic Reflex FunctionsFunctions..

These are These are represented by: represented by: Superior & Superior & Inferior Inferior ColliculiColliculi..

The massive cerebral The massive cerebral hemispheres will take an hemispheres will take an Exclusive RoleExclusive Role in many in many functions of the brainfunctions of the brain..

They becomeThey become::The Highest Levels for: The Highest Levels for:

Perception and Correlation ofPerception and Correlation of all Sensory Modalitiesall Sensory Modalities..

The Highest Level for Motor The Highest Level for Motor ControlControl..

Other CentersOther Centers:: Become progressively Become progressively

Subservient to the Cerebral Subservient to the Cerebral CentersCenters..

((11 ) )AnencephalyAnencephalyThe Brain and The Brain and

Skull are minuteSkull are minute..Incompatible for Incompatible for

livingliving..

Underdeveloped Lower Underdeveloped Lower part of the Spinal Cord part of the Spinal Cord and the Associated and the Associated Nerve RootsNerve Roots..

It may be associated It may be associated with underdevelopment with underdevelopment of the Bone and Skinof the Bone and Skin..

Anesthetic Lower Anesthetic Lower LimbsLimbs..

ParalysisParalysis..Incontinence of Incontinence of

urine and stoolurine and stool..

((33)) MeningomyeloceleMeningomyelocele::

It is Spina Bifida It is Spina Bifida withwith

The appearance of The appearance of the Meninges of the the Meninges of the Spinal Cord on the Spinal Cord on the Back of the BodyBack of the Body..