Unit 2

Question 1

Anencephaly

Answer 1

defect in the anterior fusion of the neural tube causing malformation of the cranial vault and cerebral hemispheres to the extent that they may be nonexistent all together.

about 1 in 1000 occurrence

the optic nerve does not form, so eyes may be formed and present, but they are functionally useless

Question 2

Cranium Bifidum/Spina Bifida

Answer 2

when the bone has not fused in the posterior midline of either the cranium or vertebral column, so a portion of the brain protrudes from the cranium at the posterior midline of the skull.

neural tube has not fully fused in different areas during embryonic development

Arnold-Chiari malformation is characterized by cerebellar tissue being displaced through the foramen magnum, where we should otherwise only see continuation of the brainstem into the spinal cord

Question 3

Hydrocephalus

Answer 3

enlarged ventricles due to excessive CSF production and/or obstruction of CSF drainage pathways

often associated with Arnold-Chiari malformation

results in a high-pressure state within the skull that may or may not result in intellectual disabilities, deficits in motor sensory function, or deficits in cognitive function… Individuals can also have no clear indicators/be asymptomatic.

Question 4

Microcephaly

Answer 4

brain, clavaria, and faces are significantly smaller than average, often leading to intellectual disabilities

can be caused by environmental disturbances or genetic conditions affecting proper development of the CNS.

Zika virus is a recent prominent cause of this, so we have seen an increase in cases in affected regions