The document summarizes the development of the nervous system from the ectoderm. Key points include: - The neural plate thickens to form the neural tube which will become the central nervous system. Neural crest cells emerge from the neural tube and give rise to many cell types. - The neural tube develops flexures and subdivisions that form the ventricles of the brain. Neural tube defects can occur if the tube fails to close properly. - In the spinal cord, the neural tube walls reorganize to form the central canal in the center and ventral and dorsal nerve roots on the outside, connected to gray matter inside. Ascending and descending tracts develop from nerve fibers.

1. DEVELOPMENT OF
NERVOUS SYSTEM

2. • Whole of nervous system is derived from
ectoderm. The specific cell population of early
ectoderm giving rise to CNS & special sense
organs is termed as NEURAL ECTODERM.

3. DEVELOPMENT OF NEURAL TUBE

6. NEURULATION
NEURAL PLATE
(thickening of ectoderm overlying notochord)
NEURAL GROOVE
NEURAL TUBE

9. NEURAL CREST CELLS & ITS
DERIVATIVES

10. Neural Crest Cells

12. NEURAL CREST DERIVATIVES
1. NEURONS OF DORAL NERVE ROOT GANGLIA
2. NEURONS OF SENSORY GANGLIA 5, 7,8, 9 & 10 CRANIAL NERVES
3. NEURONS OF SYMPATHETIC GANGLIA, THE PREAORTIC GANGLIA
4. NEURONS OF PARASYMPATHETIC GANGLIA OF CRANIAL NERVES
5. PARASYMPATHETIC GANGLIA OF GIT & GANGLIA RELATED TO PELVIC VISCERA
6. SCHWANN CELLS
7. SPECIFIC CELLS OF ADRENAL MEDULLA
8. CHROMAFFIN TISSUE
9. PIGMENT CELLS OF SKIN(Melanoblasts)
10. PIAMATER & ARACHNOID MATER

13. OTHER STRUCTURES DERIVED FROM NEURAL CREST CELLS
1. MESENCHYME OF DENTAL PAPILLA, ODONTOBLASTS & DENTINE
2. BONES OF FACE & PART OF VAULT OF SKULL
3. DERMIS, SMOOTH MUSCLE & FAT OF FACE & VENTRAL ASPECT OF NECK
4. MUSCLES OF CILIARY BODY
5. SCLERA & CHOROID OF EYE
6. SUBSTANTIA PROPRIA & POST. EPITH. OF CORNEA
7. CONNECTIVE TISSUE OF THYROID, PARATHYROID, THYMUS & SALIVARY GLANDS
8. DERIVATIVES OF 1, 2 & 3 PHARYNGEAL CARTILAGES
9. C- CELLS OF THYROID GLAND
10. CARDIAC SEMILUNAR VALVES & CONOTRUNCAL SEPTUM
11. SMOOTH MUSCLES OF BLOOD VESSELS OF FACE & FOREBRAIN
12. SATELLITE CELLS OF ALL SENSORY GANGLIA

14. NEURAL TUBE & ITS SUBDIVISIONS

17. FLEXURES
• CERVICAL FLEXURE: at junction of
rhombencephalon & spinal cord.
• MESENCEPHALIC FLEXURE: in region of
midbrain
• PONTINE FLEXURE: at middle of
rhombencephalon, dividing it into-
metencephalon & myelencephalon.
• TELENCEPHALIC FLEXURE: between
telencephalon & diencephalon.

21. • Each of subdivisions of developing brain
encloses a part of original cavity of neural
tube.
• The cavity of:
Telencephalic vesicle becomes LATERAL VENTRICLE
Diencephalon becomes THIRD VENTRICLE
Mesencephalon forms AQUEDUCT
Rhombencephalon forms FOURTH VENTRICLE. Its
cotinuation in spinal cord is CENTRAL CANAL.

23. NEURAL TUBE DEFECTS

24. NEURAL TUBE DEFECTS
A) NON CLOSURE OF NEURAL TUBE
1) POSTERIOR RACHISCHISIS
2) ANENCEPHALY
3) NON FUSION OF NEURAL TUBE ASSOCIATED
WITH NON CLOSURE OF :-
CRANIUM- CRANIUM BIFIDUM
VERTEBRAL CANAL-SPINA BIFIDA

26. NON-CLOSURE OF NEURAL TUBE
• POSTERIOR
RACHISCHISIS- whole
length of neural tube
ramains unclosed
• ANENCEPHALY- neural
tube remains unclosed
in region of brain

28. NEURAL TUBE DEFECTS
B) OUTWARD BULGING OF NEURAL TUBE &
COVERING MEMBRANES
1) Encephalocele- in brain
2) Myelocele- in spinal cord

29. OUTWARD BULGING OF NEURAL
TUBE & COVERING MENINGES
• SPINA BIFIDA OCCULTA
• SPINA BIFIDA CYSTICA:
1) MENINGOCELE
2) MYELOMENINGOCELE

33. DEVELOPMENT OF SPINAL CORD

34. DEVELOPMENT OF SPINAL CORD

35. • With Alar Lamina growth, dorsal
part of cavity obliterates
forming- Post. Median Septum
While ventral part of
cavity forms Central Canal.
• Further, Basal Lamina
enlarges & projects on
either side of midline
forming Ant. Median Fissure.

36. • Nerve cells of:
Basal Lamina Alar Lamina
↓ ↓
Neurons of: Ant. Grey Column Post. Grey column
↓ ↓
Axons grow out Axons forms
to form Ant. Nerve Root. Ascending Tracts.
∞Dorsal Nerve Root formed from neural crest cells.

38. • Axons of neurons in Post. GRey column enters
marginal layer forms Ascending Tracts.
• Axons of cell developing in various parts of
brain grow downwards to enter marginal layer
forming Descending Tracts.
• Marginal Layer: Asc. + Desc. Tracts= white
matter.
• Mantle layer: Alar Lamina forms Posterior
grey column & Basal Lamina forms Ventral
grey column.