Anatomy of brain and Spinal cord (nervous system .ppt

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1. Early development
•Intheearlystagesofdevelopment,threeiconic
layersoftissuedevelopwithintheembryo:the
endoderm,mesoderm,andectoderm.
•Thenervoussystemdevelopsfromasectionof
theectodermcalledtheneuralplate,which
beginstodifferentiateundertheinfluenceof
thenearbynotochordandparaxialmesoderm
aroundthethirdweek.

2. •Theedgesoftheneuralplatethenelevate
toformtheneuralfolds.Inaprocess
calledneurulation,theneuralfoldscurve
upwardandfusetoformtheneuraltube,
whichwilleventuallybecometheCNS.
Theneuralplatealsoformstheneural
crest,cellsofwhichwilllatermigrateto
differentpartsofthebodyandbecome
mostofthecellsinthePNSandANS.

3. •Neurulationbeginsinthefourthweek
ofdevelopment(aroundthe22-23
day).Theneuralfoldsfusefirstinthe
cervicalregionandcontinuetofusein
bothcranial(head)andcaudal(tail)
directionsuntilonlytheveryendsof
thetuberemainopenandconnected
withtheamnioticcavity

4. •Theseopeningsarecalledneuropores,
withtheopeningatthecranialendof
theembryobeingtherostral
neuropore,andtheopeningatthe
caudalendbeingthecaudalneuropore.
Therostralneuroporeclosesaround
day25,andthecaudalneuropore
closesapproximatelytwodaysafter.

5. Anatomy of Brain Spinal Cord

6. THE BRAIN
•Most complex organ of the body
•Only weighs 1300 grams
•Contains billions of neutral networks that
interacts to create human behaviuor
•It is center for all
thought,memory,judgment and emotion
•Each part of the brain is responsible for
controlling different body function

7. Regions of the Brain
Cerebral
hemispheres
Diencephalon
Brain stem
Cerebellum

8. Cerebral Hemispheres (Cerebrum)
Paired (left
and right)
superior parts
of the brain
Include more
than half of
the brain
mass

9. Cerebral Hemispheres (Cerebrum)
The surface
is made of
ridges (gyri)
and grooves
(sulci)

10. Lobes of the Cerebrum

11. Specialized Area of the Cerebrum
Cerebral areas involved in special
senses
Gustatory area (taste)
Visual area
Auditory area
Olfactory area

12. Specialized Area of the Cerebrum
Interpretation areas of the cerebrum
Speech/language region
Language comprehension region
General interpretation area

13. Specialized Area of the Cerebrum

14. Layers of the Cerebrum
Gray matter
Outer layer
Composed
mostly of neuron
cell bodies

15. Layers of the Cerebrum
White matter
Fiber tracts
inside the gray
matter
Example:
corpus callosum
connects
hemispheres

16. Layers of the Cerebrum
Basal nuclei –internal islands
of gray matter
Regulates voluntary motor
activities by modifying info sent
to the motor cortex
Problems = ie unable to control
muscles, spastic, jerky
Involved in Huntington’s and
Parkinson’s Disease

17. Diencephalon
Sits on top of the brain stem
Enclosed by the cerebral heispheres
Made of three parts
Thalamus
Hypothalamus
Epithalamus

18. Diencephalon

19. Thalamus
Surroundsthethirdventricle
Therelaystationforsensoryimpulses
Transfersimpulsestothecorrectpartofthe
cortexforlocalizationandinterpretation

20. Hypothalamus
Under the thalamus
Important autonomic nervous system center
Helps regulate body temperature
Controls water balance
Regulates metabolism
Controls cvsregulation heart rate and B/P

21. Hypothalamus
An important part of the limbic system
(emotions)
The pituitary gland is attached to the
hypothalamus

22. Epithalamus
Forms the roof of the third ventricle
Houses the pineal body (an endocrine
gland)
Includes the choroid plexus –forms
cerebrospinal fluid

23. Brain Stem
Attaches to the spinal cord
Parts of the brain stem
Midbrain
Pons
Medulla oblongata

24. Brain Stem

25. Midbrain
Mostly composed of tracts of nerve fibers
Reflex centers for vision and hearing
Cerebral aquaduct–3
rd
-4
th
ventricles

26. Pons
Thebulgingcenterpartofthebrainstem
Mostlycomposedoffibertracts
Includesnucleiinvolvedinthecontrolof
breathing

27. Medulla Oblongata
The lowest part of the brain stem
Merges into the spinal cord
Includes important fiber tracts
Contains important control centers
Heart rate control
Blood pressure regulation
Breathing
Swallowing
Vomiting

28. Cerebellum
Two hemispheres with convoluted surfaces
Provides involuntary coordination of body
movements

29. 2,spinal cord development
•Thecaudalpartoftheneuraltube(i.e.theneuraltube
afterthefourthpairofsomites)becomesthespinal
cord.Asthewallsoftheneuraltubethicken,the
neuralcanalbecomessmallerandsmaller,untilonly
averythincentralcanalremains
•Theneuroepitheliumsurroundingthiscanal
transitionsfrompseudostratifiedcolumnarependymal
epithelium(thecelllayersurroundingtheventricles,
constitutingtheventricularzone)toinsteadform
neuronsandmacroglia(includingastrocytesand
oligodendrocytes)withinthespinalcord.

31. Spinal nerves and vertebral levels
•Atweekeightofgestation,theembryonicspinalcord
spanstheentirelengthofvertebralcanal,andthe
spinalnervespassthroughtheintervertebralforamina
attheexactlevelthattheyemergefromthecord.Due
todifferentgrowthrates,however,thisrelationship
doesnotlast:theembryogrowsfasterthanthecord,
andwiththiscontinuedgrowththecaudalendofthe
cordbecomesshorterandshortercomparedtothe
lengthoftheembryo.

32. By24weeks,thespinalcordstopsatthefirst
sacralvertebra(S1);whichcausestheendofthe
cordtorestaroundthesecondorthirdlumbar
vertebrae(L2,L3)inanewborninfant.By
adulthood,thecordstopsatthelowerborderofthe
firstlumbarvertebra(L1).Becauseofthislength
disparity,thespinalnerverootsinthelumbarand
sacralcordprojectobliquelyfromthespinalcord
totheircorrespondingvertebrallevelsbelow.The
nerverootsattheendofthespinalcordformthe
conusmedullaris,withthenervesbranchingout
inferiorlytoformthecaudaequina

34. •THANK YOU