Chapter 1: Nervous System Organization and Development Flashcards
What week does neurulation take place?
in the 3rd week
Alar plate is sensory or motor?
sensory
Basal plate is sensory or motor?
motor
What are the alar and basal plate separated by?
sulcus limitans
Is AFP high or low in gastrochschisis?
high
Is AFP high or low in omphalocele?
high
AFP is high or low in pregnancy of Down Syndrome?
it is low
The rostral neuropore closes at what day?
Day 25
The caudal neuropore closes at what day?
Day 27
Levels of what major products are elevated when there are rostral or caudal neuropore inability to close?
Increase in AChE (amniotic fluid acetylcholinesterase) Because of failure of neuropore closure.
Increase in AFP because of any body wall closure defect.
Failure of the rostral neuropore to close results in what condition?
anencephaly causing polyhydramnios (swallowing centers not created yet and thats the only way to rid body of amniotic fluid)
Failure of the caudal neuropore to close results in what condition?
spina bifida with myeloschisis
T/F. AFP and AChE are increased in failure of the rostral and caudal neuropore to close?
true
Adult derivatives of secondary brain vesicles.
What structures form from the telencephalon?
cerebral hemispheres, most of basal ganglia
What structures form from the diencephalon?
thalamus, hypothalamus, subthalamus, epithalamus (pineal gland), retina and optic nerve
What structures form from mesencephalon?
midbrain
What structures form from metencephalon?
pons, cerebellum
What structures form from myelencephalon?
medulla
spinal cord
Neural canal remnant from telencephalon?
lateral ventricles
Neural canal remnant from the diencephalon?
third ventricle
Neural canal remnant of the mesencephalon?
cerebral aqueduct
Neural canal remnant from the metencephalon?
fourth ventricle
Neural canal remnant from the myelencephalon?
central canal
possibly some overlap with 4th ventricle
What is the pathology behind anencephaly?
failure of anterior neuropore to close
What are some signs and symptoms of anencephaly? Some lab values?
- brain does not develop
- incompatible with life
- increased AFP during pregnancy and AChE
Spina bifida occulta cause?
- failure to induce bone growth around the spinal cord
- vertebrae fail to form around the spinal cord
Is there an increase in AFP in cases of spina bifida occulta?
no
Signs and symptoms of spina bifida occulta?
asymptomatic; tuft of hair over defect
Spina bifida with meningocele cause? Relative AFP levels? Relative AChE levels?
- meninges protrude through vertebral defect
- increase in AFP; no increase is AChE
Spina bifida with meningomyelocele characteristics?
meninges and spinal cord protrude through vertebral defect
What is a condition that Spina bifida with meningomyelocele is seen with?
Arnold-Chiari type II
Is there an increase in AFP with spina bifida with meningomyelocele?
increase in AFP
What is the most severe form of spina bifida?
spina bifida with myeloschisis
Can spina bifida with myeloschisis be seen externally?
yes
What lab values are increased in spina bifida with myeloschisis?
increase in AFP and AChE
Signs and symptoms of Arnold Chiari Type I?
- mostly asymptomatic
- downward displacement of cerebellar tonsils through foramen magnum
There is an association of Arnold- Chiari Type I malformation with what condition?
syringomyelia
What are the signs and symptoms of Arnold Chiari Type II? What is it?
- more often symptomatic
- downward displacement of cerebellar vermis
- compression of IV ventricle > obstructive hydrocephaly
- frequent lumbar meningomyelocele
What is Dandy-Walker malformation caused by?
- failure of foramina of Luschka and Magendie to open > dilation of IV ventricle
- agenesis of cerebellar vermis and splenium of the corpus callosum
What is hydrocephalus most often caused by?
stenosis of cerebral aqueduct
CSF accumulates in ventricles and subarachnoid space
Signs and symptoms of hydrocephalus?
increased head circumfrence
What is holoprosencephaly? Major characteristics?
- incomplete separation of cerebral hemispheres (right and left cerebral hemispheres)
- one ventricle in telencephalon
What chromosomal abnormality is often present in infants presenting with holoprosencephaly?
trisomy 13 (Patau)
