Lec 2 Neuroembyology

7/29/2019 Lec 2 Neuroembyology

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CENTRAL NERVOUS SYSTEM


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LEARNING OBJECTIVES

Formation of notochord, neural plate, and neural

folds.

Formation of the neural tube and description of its

dilatations. Development of spinal cord, differentiation of

neuroepithelial cells, and formation of spinal

nerves.

Congenital malformations including neural tube

defects of spine (spina bifida).

Ventricular system development and its

abnormalities.


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LEARNING OBJECTIVES

Development of medulla oblongata, pons, andcerebellum.

Development of mid brain.

Structures developing from diencephalon andtelencephalon including development of pituitarygland.

Cranial nerve nuclei origins in brain.

Development of peripheral nervous system. Neural crest cells and their derivatives.

Neural tube defects affecting brain (anencephaly,meningocele, meningoencephalocele,meningohydroencephalocele).


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Changes in the Germ disc3rdweek

The ectodermal layer of the disc differentiates into three

functional zones

Surface ectoderm

Neuro ectoderm

Primitive streak


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Primitive streak

Cells in the caudal part of the germ disc proliferate to form a

linear opacity known as primitive streak

These are plur ipotent cel ls

It is considered that the primitive streak gives rise to a new

wave of cells to all the germ layers

Therefore forming definitive endoderm & ectoderm


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NOTOCHORD


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NEURAL PLATE


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NEURAL TUBE


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NEURAL TUBE


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NEURAL TUBE

Cranial part gives rise to brain and consistsof:

3 Dilatations

Prosencephalon

Mesencephalon

Rhombencephalon

2 Flexures

Cephalic flexure

Cervical flexure

Caudal part gives rise to spinal cord.


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SPINAL CORD


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SPINAL CORD

CENTRAL CANAL

3 LAYERS

NEUROEPITHELIAL

MANTLE

MARGINAL


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NEUROEPITHELIAL CELLS

DIFFERENTIATION OF


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DIFFERENTIATION OF

NEUROEPITHELIAL CELLS


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MANTLE LAYER

GRAY MATTER OF SPINAL CORD

BASAL PLATES

ALAR PLATES

ROOF PLATES

FLOOR PLATES

VENRAL HORN DORSAL HORN

INTERMEDIATE HORN


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MANTLE LAYER


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FORMATION OF NEURON


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SPINAL NERVES


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MYELINATION


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POSITIONAL CHANGES OF THE

CORD


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CONGENITAL ABNORMALITIES

OF SPINAL CORD


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SPINA BIFIDA


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BRAIN


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NEURAL TUBE


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NEURAL TUBE

VENTRICLES OF BRAIN


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VENTRICLES OF BRAIN 4 in number.

2 lateral ventricles present in telencephalon.

3rd ventricle in diencephalon.

4th ventricle in rhombencephalon.

Lateral ventricles open into 3rd ventricle through

foramen of Munro. 3rd and 4th ventricles are connected through aqueduct

of Sylvius present in the mesencephalon.

4th ventricle opens into subarachnoid space through amedial opening, the foramen of Magendie and 2lateral openings, the foramina of Luschka.

4th ventricle is continuous with central canal of spinalcord.

FORMATION OF FLEXURES


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FORMATION OF FLEXURES

Cephalic flexure Bt fore

and hind brain. Present in mid

brain region.

Cervical flexure Bt

medulla and spinal cord.

Rhombencephalicisthmus Bt Mesencephalon and

Rhombencephalon

Pontine flexure Bt

Mylencephalon andMetencephalon

Telencephalic flexure Bt

telencephalon and

diencephalon.


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PROSENCEPHALONTELENCEPHALON

(CEREBRAL CORTEX, CAUDATE AND

LENTIFORM NUCLEI) AND DIENCEPHALON

(PINEAL BODY, THALAMUS,

HYPOTHALAMUS, NEUROHYPOPHYSIS OF

THE PITUITARY GLAND, MAMILLARY BODY,SUBTHALAMIC NUCLEUS, RETINA).

MESENCEPHALON (MID BRAIN)

SUBSTANTIA NIGRA, NUCLEUS RUBER. RHOMBENCEPHALONMETENCEPHALON

(PONS AND CEREBELLUM) AND

MYLENCEPHALON (MEDULLA OBLONGATA)


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MYLENCEPHALON


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MYLENCEPHALON

METENCEPHALON


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METENCEPHALON


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CEREBELLUM


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CEREBELLUM


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PONS


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MESENCEPHALON (MID BRAIN)

PROSENCEPHALON


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PROSENCEPHALON


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CEREBRAL HEMISPHERE


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DIENCEPHALON

PITUITARY GLAND


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PITUITARY GLAND


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PITUITARY GLAND

RATHKES POUCH

ADENOHYPOPHYSIS, PARS

TUBERALIS, PARS INTERMEDIA. DIENCEPHALON (INFUNDIBULUM)

NEUROHYPOPHYSIS (PARS

NERVOSA), STALK.

CRANIAL NERVES


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CRANIAL NERVESTelencephalon Olfactory (I) Sensory

Diencephalon Optic (II) Sensory

Mesencephalon Oculomotor (III)

Trochlear (IV)

Motor,

parasympathetic

Motor

Metencephalon Trigeminal (V)

Abducens (VI)Facial (VII)

Vestibulocochlear

(VIII)

Sensory, motor

MotorSensory, motor,

parasympathetic

Sensory


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CRANIAL NERVES

Mylencephalon

Cervical spinalcord

Glossopharyngeal

(IX)

Vagus (X)

Accessory (XI)

Hypoglossal (XII)

Spinal accessorynerve (XI).

Sensory, motor,

Parasympathetic

Sensory, motor,

Parasympathetic

Motor

Motor

Motor

SYMPATHETIC NERVOUS


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SYMPATHETIC NERVOUS

SYSTEM

PARASYMPATHETIC NERVOUS


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PARASYMPATHETIC NERVOUS

SYSTEM

NEURAL CREST CELLS


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NEURAL CREST CELLS


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Derivatives of neural crest Dorsal nerve root ganglia (sensory) in spinal cord.

Preaortic ganglia of sympathetic system Parasympathetic ganglia of cranial nerves like ciliary,

submandibular, sphenopalatine, and otic ganglia.

Parasympathetic ganglia of GI tract and pelvic viscera

Schwann cells Adrenal medulla

Melanoblasts

Chromaffin tissue

Parafollicular C cells of thyroid Bones of face and part of vault of skull

Derivatives of first, second, and third pharyngeal cartilages

Conotruncal cushions in the cardiovascular system

Laryngeal cartilages in respiratory system


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CONGENITAL ABNORMALITIES


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OSSIFICATION DEFECTS

MENINGOCELE MENINGOENCEPHALOCELE


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OSSIFICATION DEFECTS

MENINGOHYDROENCEPHALOCELE


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HYDROCEPHALUS

AQUEDUCTAL STENOSIS

ARNOLD-CHIARI MALFORMATION

DANDY-WALKER SYNDROME


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EXENCEPHALY FAILURE OF

CLOSURE OF CEPHALIC PART OF

NEURAL TUBE.

ANENCEPHALY

MICROCEPHALY


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HOLOPROCENCEPHALY Loss of

midline structures in the brain and face.

SCHIZENCEPHALY Large clefts in the

cerebral hemispheres.


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HYPOPHYSEAL DEFECTS

PHARYNGEAL HYPOPHYSIS

CRANIOPHARYNGIOMA

CONGENITAL MEGACOLON

(HIRSCHSPRUNG DISEASE) Due to

defective migration of neural crest cells tothe gut to form its nervous plexus.

Lec 2 Neuroembyology

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