Defects in the Development of the Central Nervous System (Easy to Understand)

Abnormalities in the development of the central nervous system explained very briefly.

For a thorough understanding, and if you have the time, I highly recommend you watch this video on the development of the central nervous system:    • Embryology of the CNS (Easy to Understand)  

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Easy Embryology is a book that is dedicated to the simplification of embryology. It is available at https://drminass.com/product/easyembr.... Contact Dr. Minass for more information.

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SUMMARY OF THE VIDEO FOR YOUR NOTES:
Anencephaly
failure of anterior neuropore to close resulting in failure of brain and
Holoprosencephaly
failure of prosencephalon to divide and form cerebral hemispheres
Associated with the following syndromes:
1. Patau syndrome (trisomy 13)
2. Edwards syndrome (trisomy 18)
3. Severe foetal alcohol syndrome
4. Cleft lip/palate
Posterior Fossa Abnormalities
Dandy-Walker syndrome
Arnold Chiari I: cerebellar tonsil herniation through foramen magnum
Arnold Chiari II: results in aqueductal stenosis and hydrocephaly and
can present with syringomelia
symptoms present from compression of medulla oblongata and CN IX, X, and XI

A quick overview of the development of the brain:
1. The notochord induces the overlying ectoderm to differentiate into neuroectoderm and form the neural plate.
2. The neural plate folds and pinches, becoming the neural tube which is open at both ends.
3. As the neural plate folds, some cells differentiate into neural crest cells and form a column of cells along both sides of the neural tube (later becomes the peripheral nervous system - PNS).
4. The rostal part of the neural tube becomes the adult brain.
5. The caudal part of the neural tube becomes the spinal cord.
6. The lumen of the neural tube gives rise to the ventricular system of the brain and central canal of the spinal cord.