2) Development of the Nervous System Flashcards
When is the nervous system most susceptible to insult?
Pre-natal development
Where does the fusion of the neural tube begin?
Future cervical region and proceeds in both cranial and caudal directions
What are the last parts of the neural tube to close?
Anterior (day 25) and posterior (day 28) neuropores
What is anencephaly?
Cranial neural tube defect leading to absence of cranial structures, including the brain
What is is rachischisis?
Failure of neural fold elevation so no neural tube
Give an example of a caudal neural tube defect:
Spina bifida
Where does spina bifida occur must often?
Lumbosacral region
Why do neurological deficits occur in spina bifida?
Impairments of normal development of spinal cord and nerves
How can neural tube defects be diagnosed?
Raised maternal serum alpha-fetoprotein (open defect)
USS
Hoe can neural tube defects be prevented?
Folic acid pre-conceptually (3 months) and for first trimester
What condition almost always occurs with spina bifida?
Hydrocephalus which can lead to cognitive delay
What is the cauda equina and its relevance to lumbar puncture?
Bundle of spinal roots and nerves at L2/3
Do lumbar puncture at L3/4 or L4/5 after spinal cord has terminated
What are the 3 primary brain vesicles?
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
What are the 5 secondary brain vesicles (and their derivatives)?
Telencephalon and diencephalon (from forebrain)
Mesencephalon (midbrain)
Metencepahlon and myelencephalon (hindbrain)
What is the mature derivative of the diencephalon?
Thalamus
What is the mature derivative of the mesencephalon?
Midbrain
What are the mature derivatives of the metencepahlon?
Pons and cerebellum
What is the mature derivative of the myelencephalon?
Medulla oblongata
What are the two flexures and where do they form?
Cervical flexure - spinal cord-hindbrain junction
Cepahlic flexure - midbrain
How does the ventricular system form?
Tubular structure of neural tube persists to form interconnected reservoirs
How can hydrocephalus be treated?
Shunting CSF into jugular venous system or peritoneum
What is the function of the roof and floor plates in the neural tube?
Regulate dorsal-ventral patterning
Describe the roof plate of the neural tube:
Alar plate and is sensory
Describe the floor plate of the neural tube:
Basal plate and is motor
Where do the neural crest cells originate from and travel to?
Lateral border of the neuroectoderm tube and become displaced and enter mesoderm
What are some nervous system neural crest cell derivatives?
Cranial nerve ganglia, dorsal root ganglia, symp and parasymp ganglia, Schwann cells, leptomeninges
What are some head and neck neural crest cell derivatives?
CT and bones of skull and face, odontoblasts, dermis, C cells of thyroid
What are some other neural crest cell derivatives?
Melanocytes and adrenal medulla
How can defects of migration affect neural crest cells?
Can affect single component or multiple
Vulnerable to environmental insult (alcohol) and genetic
Give an example of a condition caused by defects of neural crest migration affecting one structure:
Hirschsprung’s disease - aganglionic megacolon
Give an example of a condition caused by defects of neural crest migration affecting multiple structures:
DiGeorge syndrome
