Flashcards in Neuro Embryology EC Deck (18):
Describe the development of the neural tube
Notochord induces overlying ectoderm to differentiate into neuroectoderm and form the neural plate
Neural plate gives rise to the neural tube and neural crest cells
Notochord becomes nucleus pulposus of the intervertebral disc in adults
What are the Alar and Basal plates?
What are the three primary vesicles of the developing brain?
To what structures does the prosencephalon give rise?
Telencephalon --> Cerebral hemispheres/Lateral ventricles
Diencephalon --> Thalamus/Third ventricle
To what structures does the mesencephalon give rise?
Mesencephalon--> Midbrain/Cerebral aqueduct
To what structures does the rhombencephalon give rise?
Metencephalon--> Pons and Cerebellum/upper 4th ventricle
Myelencephalon--> Medulla/lower 4th ventricle
What is the mechanism of neural tube defects?
Neuropores fail to fuse (4th week) --> persistent connection between amniotic cavity and spinal canal.
Failure of bony spinal canal to close but no structural herniation. Seen at lower vertebral levels. Dura intact and tuft of hair or skin dimple observed at level of bony defect.
Spina bifida occulta
Meninges (but not spinal cord) herniate through spinal canal defect
Meninges and spinal cord herniate through spinal canal defect
Malformation of anterior neural tube resulting in no forebrain, open calvarium (frog-like appearance). Clinical findings: Increased AFP, polyhydramnios,
Associated with maternal diabetes
Maternal folate supplementation decreases risk
Failure of left and right hemispheres to separate; usually occurs during weeks 5-6. Complex multifactorial etiology that may be related to Shh pathway. Moderate form has cleft lip/palate, most severe form results in cyclopia.
Significant cerebellar tonsillar and vermian herniation through foramen magnum with aqueductal stenosis and hydrocephalus. Often presents with thoraco-lumbar myelomeningocele and paralysis below defect.
Chiari II malformation
Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle. Associated with hydrocephalus and spina bifida
Cystic enlargement of central canal of spinal cord. Results in "cape-like" bilateral loss of P/T in upper extremities (fine touch preserved).
Associated with Chiari I
Taste and sensation in anterior 2/3 of tongue
Taste and sensation in posterior 1/3 of tongue