Development of nervous system

well describes the development of nervous system from basic to advanced concept including neural tube defects. the concepts are presented in graphical form for easy understanding of concepts.

1. To MBBS 2
nd
year
DrLaxman Khanal
Assistant Professor, Department of Anatomy
BPKIHS, Dharan, Nepal
12-02-2017
Development of
nervous system

2. Cranial nerves
1.Motor parts
2.Sensory parts
3.Autonomic parts
Parasympathetic
Spinal nerves
1.Motor parts
2.Sensory parts
3.Autonomic parts
A.Sympathetic (thoracic and lumbar
segment)
B.Parasympathetic (sacralsegment)
Parts of nervous system
1.CNS-brain and spinal cord
2.PNS-cranial and spinal nerve
3.ANS-contributed by both CNS and PNS
ANS-cardiac muscle, smooth muscle and glands.

3. Notochordactsasan
inducerfordevelopment
ofnervoussystem.
BMP
•Ectoderm
•Neuroectoderm
•Neural plate
•Neural fold
•Neural groove
•Neural tube
Neuroectoderm
Neural tube
Edge of Neuroectoderm
and embryonic ectoderm
Neural crest cells
Embryonic ectoderm
Ectodermal derivatives

4. Development of
neural crest cells
Epithelial Mesenchymal
E-Cadherin

5. Pharyngeal arch derivatives
•Skeletal component
•Nerves and ganglia of each arch
•Dermis overlying each arch
•Blood vessels of face.
Migration of neural crest cells

6. Cranial neuropore
Closure at 25
th
day
Caudal neuropore
Closure at 27
th
day
Brain
SC
Alphafetoprotein(AFP)increases
inmaternalAFifneuroporesfailto
close(neuraltubedefects).

7. Anencephaly
Craniorachischisis
Neural tube defects of cranial part of neural tube

8. Neural tube defects of caudal part of neural tube
Rachischisis
Myelomeningocele
Spinabifida occulta

9. Prevented by maternal use of folic acid prior to and during pregnancy.
Spinabifida occulta
Meningocele Myelomeningocele
Rachischisis

10. Anterior portion of neural tube forms
three primary brain vesicles.
1.Prosencephalon: Telencephalon + Diencephalon
2.Mesencephalon:
3.Rhombencephalon: Metencephalon+ Mylencephalon
I & II CN
III & IV CN
V-XII CN

11. Development of ventricular system
4
th

12. Development of spinal cord
L
TS neural tube
Neuroepithelial cells
L
Neuroblast cell
L
Mantle cell layer
Marginal cell layer
L
A
B
A
B
R
F
Anterior horn
Posterior horn
intermediate horn
Sensory
Motor
Autonomic

13. Neuroblast
Glioblast
Microglial cells
Ependymal cells
Origin of various types of cells

14. Brainstem
Arrangementofalarand
basalplateisintactbut
thearrangementis
different.
Highercenter
Basalplateregressand
alarplateaccentuate.
A
B

15. G
S
E
S
V
E
G
V
E
Development of functional columns in brain stem
Basal plate –motor components
Skeletal muscle
1.Somatic muscles -GSE
2.Pharyngeal arch muscles-SVE
Smooth muscle-GVE (autonomic)
CN supplying somatic skeletal muscles
Motor nerve of pharyngeal arch
CN with parasympathetic
actions

16. G
S
E
S
V
E
G
V
E
G
S
A
S
V
A
G
V
A
S
S
A
Development of functional columns in brain stem
Alar plate-sensory column
Senses
•General senses
•Special sense-taste
•Senses from viscera
•Special sense-hearing & Eqb
Pain, touch, temperature, pressure
Taste Sense of distension of viscera
Hearing &
equilibrium

17. Mesencephalic flexure
Cervical flexure
Pontine flexure
Rhombiclip
•Postero-lateralextensionofalarplate
ofmetencephalon.
•Giverisetocerebellum.
Rhombic lip

18. TS of caudal part of Pons
Rhombic lip
Cerebellar plate
TS Mesencephalon
Alar plate
Basal plate
Alar plate
Sup colliculus
Infcolliculus
Basal plate
Nuclei of 3
rd
CN
Nucleus of 4
th
CN

19. Development of Prosencephalon
Diencephalon
3
rd
ventricle
Telencephalon
2 lateral ventricles
1.Thalamus
2.Hypothalamus
3.Epithalamus
4.Subthalamus
5.Metathalamus
6.Neurohypophysis

20. Summary
•TheCNSdevelopsfromadorsalthickeningofectoderm-theneural
plate,whichappearsaroundthemiddleofthethirdweek.
•Theneuralplateisinducedbytheunderlyingnotochordandparaxial
mesodermtoformneuraltube.
•Thecranialendoftheneuraltubeformsthebrainandtheremainder
formsthespinalcord.
•Theneuralcanal,thelumenoftheneuraltube,becomesthe
ventriclesofthebrainandthecentralcanalofthespinalcord.
•Defectsintheclosureoftheneuraltube(NTDs)accountformost
severeanomaliesofnervoussystem.