Congenital Pathology Flashcards
What structure gives rise to the fourth ventricle?
The rhombencephalon
What structure gives rise to the third ventricle?
The diencephalon
What structure gives rise to the three germinal layers?
The primitive streak
Neurenteric canals arise from ____________.
persistent canal between amniotic sac and yolk sac
Secondary neurulation occurs in a structure called the ___________.
caudal cell mass
The completed neural tube sends out nerves that split the ______________ and connect to myotomes.
somites
Failure of the neural tube to close is called _____________.
neuroschisis
Describe holoprosencephaly.
A disorder in which the telencephalon fails to develop into two hemispheres
Cranioraschisis totalis results from ____________.
absolute failure of the neural tube to close
Eyes are outpouchings of _____________.
the diencephalon
The prosencephalon gives rise to the __________.
telencephalon and diencephalon
Encephaloceles can contain _____________.
subarachnoid layer (in which the contents would be CSF) or subdural (in which the contents would be brain tissue)
Myelomeningoceles are ____________.
failures of the posterior neural tube to close
Prognosis of myelomeningoceles depends on ____________.
level of the failure; higher levels decrease the likelihood of future ambulation
Fatty filum terminale leads to _____________.
tethering of the spinal cord, which prevents its normal ascension in relation to the vertebral column
Bladder problems are common in those with ___________.
tethering of the spinal cord
Which Chiari malformation is the most mild?
Chiari I
What characterizes Chiari II (aka Arnold-Chiari)?
Meningomyelocele (failure of the neural tube) leading to bulging of the cerebellar vermis into the foramen magnum (thought to arise from the failure of the fluid support of the neural tube) and subsequent hydrocephalus (from the occlusion of the cerebral aqueduct)
The ____________ protrude into the foramen magnum in Chiari I malformation.
cerebellar tonsils
Some of the pain tracts that pass the midline come from ______________.
above and below that spinal level
Symptomatic Chiari I can be treated with _____________.
surgical decompression
When do most neural tube defects occur?
During neural tube closure, during the fourth week of development
Importantly, those with holoprosencephaly have normal ______________.
midbrain and hindbrain
Describe Dandy-Walker malformation.
A large cyst develops where the cerebellum lies, thereby preventing its growth
What Alzheimer’s protein is found on chromosome 21?
Amyloid precursor protein –(“two Ps and 1 A”)
Which kind of Chiari is not a neural tube defect?
Type I – it is “a size 5 brain in a size 4 skull”
Purely genetic CNS malformations are ___________.
rare (only 8%)
The primitive cerebral hemispheres develop by which week of gestation?
7
What are the average weights of the newborn brain and adult brain?
400 grams and 1,200 grams
Spina bifida occulta is most often a _____________ finding.
incidental, benign
What are meningoceles?
Skin-covered, CSF-filled masses continuous with the CSF of the spinal cord; synonymous with encephalocele
__________ are like less severe forms of myelomeningoceles.
Dorsal sinus tracts
What is spina bifida occulta?
Failure of the vertebral arch to fully close
Describe syringomyelia.
A condition in which a fluid-filled sac develops in the spinal cord due to obstruction of normal flow within the central canal
Agenesis of the cerebellar vermis and cystic occlusion of the fourth ventricle are characteristic of ___________.
Dandy-Walker malformations
Describe the differences between porencephaly, schizencephaly, and hydranencephaly.
All relate to cerebrovascular events that lead to clean destruction of brain tissue: porencephaly is a large, unilateral hole; schizencephaly is bilateral holes; and hydranencephaly is near complete destruction of one hemisphere.
What causes cranioraschisis totalis?
Complete failure of the neural tube to close
What cells give rise to sacrococcygeal teratomas?
The pluripotent cells of the primitive streak
Rather than arising from a defect in the neural tube, Chiari I malformations are thought to stem from _______________.
mesodermal defects (the mesoderm that produces the skull base)
What is the peak developmental period for prosencephalon development?
2-3 months
Ulegyria results from ______________.
perinatal watershed strokes
