Brain Embryology Flashcards
(63 cards)
1
Q
Development of the nervous tissue. Begins in the —–week of development
A
3rd
2
Q
Neural tube formation has other name ?!
A
Neurulation
3
Q
The whole nervous system is derived from the ——- (——–) overlying the ———-, Except…..——— and ———-
A
ectoderm - neuroectoderm
notochord
dura matter - microglia
4
Q
Elements developed from the neuroectoderm
1) ———————
2) ——————–
A
1-neural tube
2-neural crest cells
5
Q
(A) Formation of the —————-
The presence of the notochord induces the
overlaying ectoderm to be thickened and form the
neural plate
A
neural plate
6
Q
(B) Formation of the —————
The lateral edges of the neural plate(at the its
connection with the surface ectoderm ) elevates to
form the —————–.
A
neural folds
7
Q
(C) Formation of the ———————–
The mid region of the neural plate depression is
increased to form the ———————-
A
neural groove
8
Q
(D) Formation of the ——————
The neural folds approach each other and fuse in
the midline forming the —————.
A
neural tube
9
Q
Neural crest cells formation
As the neural folds fuses , cells at the lateral border
(crest of the neuroectoderm) ————— from the
surrounding cells.
They are called —————–.
They leave the neuroectoderm and migrate to various areas of the body
A
dissociate
neural crest cells
10
Q
The anterior and posterior neuropores connect the
———— with the amniotic cavity.
A
central canal
11
Q
Closure of the tube occurs in ————– direction
A
cranio-caudal
12
Q
Anterior neuropore closes on the ——- day
A
25th
13
Q
Posterior neuropore closes on the ——– day
A
27th
14
Q
Anterior part dilates and develops into the ——-
A
brain
15
Q
Caudal part develops into the ————
A
spinal cord
16
Q
The cavity gives rise to the ———– of the brain and
the ———– of the spinal cord
A
ventricles
central canal
17
Q
In the —– week: three primary brain vesicles develop.
- ———– (forebrain)
- ———– (midbrain)
- ———–(hindbrain)
A
4th
Prosencephalon
Mesencephalon
Rhombencephalon
18
Q
- In the ——— week: secondary vesicles are formed
* The 3 primary vesicles develop into —— secondary vesicles
A
5th
5
19
Q
Primary and Secondary Vesicles
- Prosencephalon (forebrain)
- It is associated with the appearance of the ————-.
- It gives rise to the —————- and diencephalon
A
optic vesicles
telencephalon
20
Q
Primary and Secondary Vesicles
-It remains as the ————
A
mesencephalon
21
Q
Primary and Secondary Vesicles
It gives rise to the ————-: forms the pons and the ———-
- the myelencephalon: forms the (—————).
A
metencephalon-cerebellum
medulla oblongata
22
Q
Brain flexures
3 ????
A
Cephalic flexure
Cervical flexure
Pontine flexure
23
Q
flexure located between the prosencephalon and the mesencephalon
A
Cephalic flexure
24
Q
flexure located between the rhombencephalon (hindbrain) and the future spinal cord
Later.. A third flexure develops(due to unequal growth between these flexures)
A
Cervical flexure
25
flexure located in the region of the future pons
• it is convex forward
• it does not affect the head
• Responsible for formation of the 4th ventricle
Pontine flexure
26
The lumen of the neural tube in the:…..
• Telencephalon will be the-------------
• Diencephalon will be the --------------
• Mesencephalon will remain as the -----------
• Hind brain (between pons , upper medulla and cerebellum) will be the -------------------
• Spinal cord will be the ------------ .
• The lumen is lined by --------- cells derived from the neuroepithelial cells (neuroectoderm).
```
lateral ventricles
3rd ventricle
cerebral aqueduct
4th ventricle
central canal
ependymal
```
27
Embryonic (developmental) divisions of the Brain
| What are the derivatives of telencephalon ?
Cerebral cortex
Cerebral white matter
Basal ganglia
28
Embryonic (developmental) divisions of the Brain
| What are the derivatives of diencephalon ?
Thalamus
Hypothalamus
Subthalamus
Epithalamus
29
Embryonic (developmental) divisions of the Brain
| What are the derivatives of metencephalon ?
Cerebellum
| Pons
30
The major part of the wall of the neural tube is formed
of ------------------.
• Later neuroepithelial cells develop into the ---------
neuroepithelial cells
| neuroblasts
31
* Neuroblasts will form the ----------------------.
| * The -------------- layer forms the grey matter
mantle layer
| mantle
32
• The marginal layer of the tube contains nerve fibers
emerging from the --------------. After myelination of the nerve fibers they appear white in color.
• The marginal layer forms the ----------------
neuroblast
| white matter
33
* Continuous addition of neuroblast to mantle layer results in ventral and dorsal thickening .
* Ventral thickening will form --------------.
* Basal plates contain ---------------cells
basal plates
| motor
34
* Continuous addition of neuroblast to mantle layer results in ventral and dorsal thickening
* Dorsal thickening will form the -----------plates
* Alar plate form the --------------area
alar
| sensory
35
----------------is a groove that that marks between alar and basal plates
The sulcus limitans
36
------------------------are dorsal and ventral midline portions. They do not contain neuroblasts. The act as a pathway for nerve fibers
The roof and floor plates
37
Differentiation of nerve cells
| The neuroblasts develop from the -----------------
neuroepithelial cells.
38
• Neuroblast migrate into the mantle layer and become
(---------------).
• They develop 2 cytoplasmic process on opposite sides of the cells (-----------).
• One process will elongate to form ------------ and
the opposite process show cytoplasmic arborizations
(multipolar).
• ------------ neuroblast further develops into the adult
neurons
apolar
Bipolar
primitive axon
Multipolar
39
---------- (Spongioblast) (supporting cells )are formed from the
neuroepithelial cells
Glioblast
40
• Glioblast migrate into mantle and marginal layers
where they differentiate into:
1.-------------- and ---------------
2.---------------: forms myelin sheath in ascending and descending tracts
protoplasmic & fibrillar astrocytes
| oligodendroglia
41
The microglia cells are derived from ---------------:
They are highly -----------
scattered in --------and-------
invade --------------- later in fetal(not embryo) development
mesenchyme (mesodermal in origin ) from the blood
phagocytic
grey matter and white matter
CNS
42
------------------------------------
- Specialized cells
- At the junction between neural plate & the rest of the
ectoderm
- Escape to lie on the dorsolateral sides of the neural
tube after its closure.
- They leave the neuroectoderm and migrate to
various areas of the body
Neural crest cells
43
Structures developed from the neural crest cells (10 )
1. Cells of the spinal and cranial nerve ganglia.
2. Cells of the autonomic ganglia.
3. Schwann cells (neurolemmal sheath cells that form myelin in the PNS).
4. Leptomeninges (pia-arachnoid).
5. Chromaffin cells in supra renal gland.
6. Pigment cells (melanocytes).
7. Odontoblasts (dentine-forming cells).
8. Parafollicular ( C ) cells (calcitonin-producing cells
9. The original mesoderm of the pharyngeal arches that gives rise to the pharyngeal muscles.
10. Skeletal and connective components of the pharyngeal arches
44
Brain Vesicle development
1.Telencephalon
- Start as lateral ---------- to form the cerebral
hemispheres at the 5th week.
- Ventral outpocketings will form the ----------------.
- By the 7th week the basal part of the hemisphere bulges into the lumen of the lateral ventricles and floor of the IVF(interventricular foramen)(connect La t.vent. with 3rd ventr.) . It has striated appearance…forming the ------------------.
- With expansion of the hemispheres , it covers the
lateral aspect of the diencephalon, mesencephalon
&cephalic portion of -----------------
Continuous growth of the hemisphere in the anterior, dorsal, inferior directions forms the ------------,---------,-----
-Lateral ventricles are visible & communicate with 3rd ventricle through interventricular -------------- (IVF)
- outpocketings
- Olfactory bulbus
- corpus striatum
- metancephalon
- frontal,temporal & occipital poles
- foramen of Monro
45
The alar plate:
• Is divided by the -------------- into thalamus and hypothalamus
hypothalamus give
• Infundibulum(connect with pit.gland) and mammillary bodies .
• Thalami expand, fuse in the midline by -------------(adhesion).
• Optic chiasma and optic nerves develops.
• -------------- ventricle is visible
- hypothalamic sulcus
- interthalamic connexus
- Third
46
Mesencephalon
Basal plate contains --- groups of motor nuclei
- Somatic efferent (------------and----------)
- General visceral efferent: (-----------------)
- Marginal part: forms crus cerebri
Alar plates
• Form ------ longitudinal elevation separated by midline
depression:(superior and inferior --------)
• cerebral aqueduct traverses it.
```
2
occulomotor and trochlear nerves
edinger westphal nucleus
2
colliquli
```
47
Rhombencephalon
forms the ----- and the -----------.
1.Metencephalon
Pons
Basal plate: contains ---- groups of motor nuclei:
• Somatic efferent: (------------)(move extra ocular muscle with 3 and 4)
• Special visceral efferent (trigeminal(mandibular supply mesti. muscles), facial(supply facial muscles),
glossopharyngeal(supply spinopharyngeus) & & vagus(supply muscles of pharynx and larynx with cranial part of 11th)))
• General visceral efferent(----------): (superior salivatory N. arise from facial nerve through chorda tympni )
Alar plate: contains ---- groups of sensory nuclei
• Somatic afferent: (trigeminal sensation from face three parts of it) (vestibulocochlear-special somatic afferent)
• Special visceral afferent (taste)
• General visceral afferent -internal aspect of the body (--------)
• gives rise to the pontine nuclei receive fibers from cerebral cortex and make a truck call corticopontine .
```
pons-cerebellum
3
abducent
3
Secretomotor
vagus
```
48
Metencephalon
---------------------------
• Develops as 2 dorsolateral outgrowths of the alar plate of the metencephalon, called the ---------.
• The rhombic lips fuse across the midline just below the mesencephalon.
• The rhombic lips compress in cephalo-caudal direction and form the cerebellar plate.
• The midline portion of the plate form the ---------------.
• The lateral portions form -------------
Cerebellum
rhombic lips
vermis
hemispheres
49
Congenital anomalies
Congenital anomalies of neural tube
- Failure of the anterior neuropore to close results in ----------
- Failure of the posterior neuropore to close results in ------------
anencephaly.
| spina bifida
50
2.Myelencephalon
- Contains the caudal --------------.
- Forms the medulla oblongata.
- the lateral walls are everted
- The roof plate is covered by --------and-------- forming tela choridea.
Basal plate contains -----groups of motor nuclei,
General Somatic efferent (GSE) (------------)
Special visceral efferent (SVE) (accessory(MS of pharynngeal arches), vagus,glossopharyngeal)
General visceral efferent(GVE) (--------------)Smooth muscles
Alar plate contains -----groups of sensory nuclei,
General Somatic afferent (GSA)(most medial one )(vestibulocochlear, trigeminal)
Special visceral afferent (SVA) (taste) 9th
General Visceral afferent (GVA)( interoceptive sensation)
```
half of the fourth ventricle
ependymal cells and pia
3
hypoglossal
3
vagus
```
51
```
Name the function of the column
Efferent (motor)(-----)
General Somatic efferent (GSE)
Special visceral efferent (SVE)
General visceral efferent(GVE)
Sensory (afferent)(----------)
General Somatic afferent (GSA)
Special visceral afferent (SVA)
General Visceral afferent (GVA)
Special somatic afferent (SSA)
```
basal plate
| alar plate
52
----------------------
- The cranial vault is smaller than normal.
- It is due to defect in brain development which may be due :
to genetic disease,
postnatal infections
exposures to drugs and other teratogens.
- Impaired mental development occurs in more than half the cases.
Microcephaly
53
-------------- defects of the occipital bone
include the following variations:
- Cranial meningocele(only cyst of meninges),
- Meningo-encephalocele(meninges and part of brain tissue)
- Meningo-hydroencephalocele.(meninges and ventricles(CSF) and brain )
Ossification
54
2. ----------------
- Causes: failure of the anterior neuropore to close resulting in failure of formation of vault(bone) of the skull.(neural crest cellداخله في السالفة)
- a rudimentary brain stem is usually present and no cranial vault is formed. will die within few hours
- occurs once in every 1000 births.
- is the most common serious birth defect seen in stillborn fetuses.
- ---------------- levels increase in amniotic fluid and maternal serum
-Anencephaly
-Alpha fetoprotein ( AFP) first synt. by liver then yolk sac
and may inc . in mother's blood
55
Types of Hydrocephalus
| ---------:results from increased production/ decreased absorption
-Communication hydrocephalus:
56
----------------------
- is the dilation of the ventricles due to an excess of cerebrospinal fluid (CSF).
Causes
- blockage of CSF circulation; commonly obstruction of cerebral aqueduct of sylvius يتجمع
- overproduction of CSF or impaired absorption.
- Results in widening of the cranial sutures مساحه كافيه للتمدد
Hydrocephalus
57
Mesencephalon
In Basal plate there is collect of cell bodies in CNS 2 groups
---------------
---------------- supply gland to secrete , this nucli follow oculomoter nerve
So that explain why oculomoter has different functions due to different nucli
So groos oculomoter nerve come from this nucli
Marginal layer 3 parts
just is fibers mainly descending
Mesencephalon
Somatic efferent
General visceral efferent
58
Mid brain ----- and ----
Pons ------ and ------ and -----and--------
MO ------------,-------,---------,--------
3-4
5-6-7-8
9-10-11-12
59
Types of Hydrocephalus
---------------:Results from obstruction within the ventricle system (e.g., aqueductal occlusion).
The infant has an enlarged head, prominent brow, downwardlooking
eyes, and distended scalp veins
-Non-communicating hydrocephalus
| cerebral aqueduct of Sylvi
60
Superior salivary nucleus in ---------
pons
61
dorsal nucleus of --------- in M.O
vagus
62
NUCLI OF TRIGMENAL IN ALL------
BRAIN STEM
63
nuclei in alar plate change its position from medial to lateral due to ------------
pontine flexure
