Nervous System Flashcards
0
Q
When does the process of neurolation occur?
A
~day 22
1
Q
What is neuralation?
A
formation of neural plate and neural tube
2
Q
What induces the formation of the neural plate?
A
notochord and paraxial mesoderm
3
Q
Where does neural tube closure begin near?
A
somite pair 4
4
Q
When does the cranial neuropore close?
A
day 25
5
Q
When does the caudal neuropore close? And what does this establish?
A
day 27, establishment of neural tube vasculature
6
Q
What will the neural canal form?
A
- ventricles of the brain
- central canal of SC
7
Q
Where does the development of the spinal cord occur?
A
caudal to somite 4
8
Q
What initially lines the neural tube?
A
pseudostratified columnar neuroepithelium
9
Q
What does the ventricular zone refer to?
A
refers to the original neuroepithelium
10
Q
What does the ventricular zone give rise to?
A
gives rise to spinal cord neurons, spinal cord astrocytes, oligodendrocytes and ependymal cells
11
Q
How does the intermediate zone form?
A
forms by proliferation in the original ventricular zone
12
Q
What does the intermediate zone form?
A
neuroblasts
- differentiate into spinal cord neurons
13
Q
Where does the marginal zone form? what does it become?
A
- peripheral to the original ventricular zone
- becomes white matter as neuronal processes grow into it from spinal cord and brain
14
Q
Where do glioblasts reside?
A
populate ventricular, intermediate, and marginal zones
15
Q
What do glioblasts become?
A
- astroblasts => astrocytes
- oligodendroblasts => oligodendrocytes
16
Q
What do ependymal cells persist as? what zone where they associated with?
A
- ependyma lining the central canal
- ventricular zone
17
Q
What are microglial cells differentiated from?
A
mesenchyme
18
Q
Where do microglial cels originate from?
A
bone marrow
19
Q
What happens to the spinal cord as the neuroepithelial cells proliferate and differentiate?
A
spinal cord walls become think and roof and floor become thin
20
Q
What is the sulcus limitans?
A
shallow longitudinal groove on either side of central canal lumen
21
Q
What is the alar plate?
A
dorsal longitudinal bulge in the intermediate zone
22
Q
What will the alar plate become?
A
dorsal columns in the grey matter
23
Q
What are located in the dorsal columns of thee grey matter?
A
afferent neurons
24
When does the dorsal median septum form?
as alar plate enlarge bilaterally
25
What is the basal plate?
ventral longitudinal bulge in the intermediate zone
26
What will the basal plate become?
the ventral and lateral columns in the gray matter
27
What is located within the lateral columns in the gray matter?
efferent neurons
28
When does the ventral median fissure form?
as basal plates enlarge bilaterally
29
Where are pseudounipolar neurons derived from?
neural crest cells
30
What passes through the DRG to enter the spinal cord?
central processes
31
Primordial meninx is a membrane that develops from what?
mesenchyme surrounding the neural tube
32
What is dura mater?
thickened external layer (mesenchyme origin) or primordial meninx
33
What are leptomeninges?
Internal layer (neural crest origin) of the primordial meninx
34
What is subarachnoid space?
- separates leptomeninges into arachnoid and pia mater
| - production begins week 5
35
What is the position of the SC in embryo?
SC extends entire length of vertebral canal
| - spinal nn. exit intervertebral foramina opposite their level of origin
36
What is the position of the SC in a 6mo fetus?
SC conus medullaris extends to S1 vertebra
37
What is the position of the SC in a newborn infant?
SC conus medullaris extends L2 or L3 vertebra
38
What is the position of the SC in an adult?
- SC conus medullaris extends to inferior border of L1
- cauda equina
- dura and arachnoid end at S2 (filum terminale externum)
- pia extends as filum terminale internum to Cx1
39
CNS myelin is produced by what?
oligodendrocytes
40
Myelination of neuronal processes occurs when?
in late fetal period and continues through year 1 postnatally
41
Which are myelinated first, motor or sensory fibers?
motor
42
What does a spinal dermal sinus indicate?
Indicated site of closure of caudal neuropore
| - last site of separation of surface ectoderm from neuroectoderm
43
What is spinal dermal sinus?
posterior median skin dimple in sacral region
44
What causes spina bifida occulta?
due to failure of embryonic halves of vertebral arch to grow and fuse in midlinw
45
Where does spina bifida occulta occur?
L5-S1 in ~10% of people
46
Does spina bifida occulta usually show clinical symptoms?
No
47
What evidence if any does spina bifida occulta show?
small dimple with a tuft of hair
48
What does spina bifida cystica involve?
protrusion of spinal cord and/or meninges through vertebral arch defect
49
What is present with spina bifida cystica?
a cyst-like sac
50
What is the occurrence/frequency of sspina bifida cystica?
1/1000
51
What neurological deficits accompany spina bifida cystica?
- dermatomal sensory loss
- complete or partial skeletal muscle paralysis
- lumbosacral defects => sphincter paralysis
52
What can be done to detect spina bifida cystica?
- amniocentesis to confirm Alpha Fetoprotein levels (will be high if cystica present) in amniotic fluid
- ultrasound can detect cyst 10-12weeks
53
What are 2 subtypes of spina bifida cystica? their occurence?
- spina bifida with meningocele (10%)
| - spina bifida with meningomyelocele (90%)
54
What is present in cyst-like sac in spina bifida with meningocele?
meninges and CSF
55
What is in the cyst-like sac in spina bifida with meningomyelocele?
spinal cord and/or spinal roots
56
Is surgery and option with spina bifida with meningomyelocele?
surgery is possible but no functional restoration occurs
57
What is myeloschisis?
most severe type of spina bifida
| - spinal cord is open caudal neuropore failed to close
58
What is the importance of Folic Acid supplements?
reduce the chance of neural tube deficits
59
Where does the brain develop?
cranial to somite pair 4
60
What are the 3 primary brain vesicles?
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
61
What primary brain vesicles give rise to secondary brain vesicles in the 5th week?
prosencephalon and rhombencephalon
62
What 2 secondary brain vesicles does the prosencephalon form?
- Telencephalon
| - Diencephalon
63
What 2 secondary brain vesicles does the rhombencephalon form?
- Metencephalon
| - Myelencephalon
64
What primary brain vesicle doesnt dived?
mesencephalon
65
What are the 3 flexures?
- midbrain flexure
- cervical flexure
- pontine flexure
66
Where is the midbrain flexure?
- ventral fold in the midbrain region
67
Where is the cervical flexure?
ventral fold at the junction of the hindbrain and the spinal cord
68
Where is the pontine flexure located?
dorsal fold between the midbrain and the cervical flexures
69
What is the function of the pontine flexure?
divides the brain into its 2 respective parts
- metencephalon (rostrally)=> pons & cerebellum
- myelencephalon (caudally)=> medulla oblongata
70
The pontine flexure produces a cavity which becomes what?
the IV ventricle
71
What does the caudal region of the developing myelencephalon resemble?
resembles the developing spinal cord
| - closed part of the medulla
72
What nuclei are present in the myelencephalon?
- gracile nuclei
| - cuneate nuclei
73
What white tract is present in the myelencephalon?
pyramids
74
What will the walls of the metencephalon form?
cerebellum and pons
75
What spreads the lateral walls of the metencephalon?
pontine flexure
| - spreads gray matter in the floor of the IV ventricle
76
What is the pons and where is it located in the developing brain?
It is a bridge of large tracts connecting cerebral cortex and cerebellar cortex and it is located within the metencephalon
77
What is choroid plexus and where is it developed?
- developed in roof of IV, III ventricle and medial walls of the lateral ventricles
- produces CSF
78
What are the outpouchings from the IV ventricle called?
median and lateral aperatures
79
Does the mesencephalon undergo a lot of change?
comparatively little change
80
What happens to the neural canal in the mesencephalon?
narrows to become the cerebral aqueduct
81
What are the three swellings in the diencephalon?
- epithalamus
- thalamus
- hypothalamus
82
Where is the pineal gland?
median growth of caudal part of diencephalon roof associated with the epithalamus
83
What is melatonin and from what is it secreted from?
regulates circadian rhythm and is secreted from the pineal gland
84
How often do the thalamus sides fuse in midline?
70% of brains
85
What is the function of the thalamus?
relay station for afferent information heading to cerebral cortex
86
What is the function of thee hypothalamus?
coordinates many endocrine activities in the body
87
What does the hypothalamus regulate?
autonomic nervous system
| - BP, body temp, fluid/ion balance, body weight, appetite, etc.
88
What does the pituitary gland work with?
works with the hypothalamus as a major controller of the endocrine system
89
The Neurohypophysial diverticulum is a downgrowth of what?
diencephalon
90
What does the neurohypophysial diverticulum form?
The posterior lobe (nervous part)
91
What is the name of the posterior lobe of the pituitary?
neurohypophysis
92
What does the connection of the pituitary to the diencephalon persist as?
infundibulum
93
What do neurosecretory cells secrete?
oxytocin & ADH
94
What is the upgrowth from the roof of the stomodeum?
hypophysial diverticulum
95
What does the hypophysial diverticulum form?
anterior lobe (glandular part)
96
What is the name of the anterior lobe of the pituitary?
adenohypophysis
97
What does the adenohypophysis secrete?
TSH, ACTH, FSH, LH, PRL, GH
98
Cavities in the primordial cerebral hemispheres become what?
lateral ventricles
99
What do the lateral ventricles interact with? and how?
III ventricle and through the interventricular foramen
100
Where is the choroid plexus located in the lateral ventricles?
the medial walls
101
What grows more rapidly in the cerebral hemispheres?
the walls and roof grow more rapidly than the floor
102
Trapped mesenchyme in the midline becomes what?
falx cerebri
103
How does the temporal lobe form?
caudal end of cerebral hemispheres turn ventrally and rostrally
104
Which commissure forms first?
anterior commissure
105
The cortical surface is smooth or bumpy initialy?
smooth
106
What happens to the surface area of the brain as the cortex grows? what causes this?
Increases surface area due to gyri and sulci
107
What is the medullary center?
large volume of myelinated processes in the "core" of the brain
108
What bony landmarks are usually associated with cranium bifidum?
squamous occipital bone and/or posterior foramen magnum
109
What is cranial meningocele?
small defect with only meninges herniated
110
What is cranial meningoencephalocele?
large defect with brain and meninges herniated
111
What is cranial meningohydroeencephalocele?
large defect with brain, ventricular components and meninges herniated
112
What is meroencephaly?
severe anomaly due to failure of rostral neuropore to close
| - brain and calvarium (acrania) don't develop normally
113
What is exencephaly?
brain is exposed or extruding from cranium
114
What is anencephaly?
misnomer for rostral neuropore closure defects
115
What is microcephaly?
brain and calvarium are small; face is normal
116
What is hydrocephaly?
imbalances between CSF production and absorption => accumulation in ventricular system
117
Congenital aqueductal stenosis is a common form of what?
Hydrocephalus
118
What is congenital aqueductal stenosis?
narrowing and blockage primarily of lateral and III ventricles
- genetic and environmental causes
119
What happen to cranial bones when ventricular fluid accumulates in the cranium?
expand and thin
120
What is Arnold-Chiari malformation?
Inferior displacement of vermis of cerebellum through foramen magnum
121
What are sensory neurons derived from?
neural crest cells
122
In the regions of the DRG sensory neurons start out as what? and become what later?
bipolar neurons => unipolar
123
Where does the peripheral process terminate?
sensory endings
124
What aspect of a sensory neuron terminates in the SC or extends up to the brain?
central process
125
What are satellite cells?
ganglion support cells derived from neural crest cells
| - modified schwann cells
126
What emerges from the ventrolateral aspect of SC as ventral root?
motor neurons
127
What do dorsal primary ramus supply?
skin, muscles etc on back
128
What do ventral primary ramus supply?
skin, muscles etc in limbs and ventrolateral body wall
129
What are Schwann cells?
neural crest cells that migrate into position to myelinate sensory and motor neurons
