1.3 Development of CNS and PNS Flashcards
Define gyrus…
Raised bit of the fold of the cerebrum
Define sulcus…
Dip of the fold of part of the cerebrum
Which part of the cortex is in the post central sulcus?
Sensory
Which part of the cortex is in the pre central sulcus?
Motor
What is the cortex?
Thin layer of grey mater in the cerebrum
At which week does CNS development occur?
Week 3
Which part of the embryo forms the NEURAL PLATE?
It is formed by the ectoderm in the mid dorsal region.
What other cells do the neural crest cells form?
Parafollicular cells of thyroid Dorsal root ganglion Melanocytes Odontoblasts - teeth Adrenal medulla Autonomic ganglia Trocheal cartilage Schwann cells
What forms the ventricles?
Neural tube lumen
Where does fusion of the neural tube begin?
Cervical region
How does the cavity of the tube remain in communication with the amniotic cavity?
Cephalic and caudal neuropores
Which neuropore closes first and at which day?
Cephalic - day 25
Caudal - day 27
Which conditions can occur if the neuropores don’t close correctly?
Cephalic - anencephaly
Caudal - spina bifida
What can prevent the incorrect closing of these neuropores?
Folic acid - 400micrograms
How can a fusion deficit be detected?
Ultrasound scan and mother’s raised levels of alpha-fetoprotein
Explain; meningocele, myelomeningocele and spina bifida occulta
Meningocele - Protrusion of meninges through a gap in the spine
Myelomeningocele - Spinal cord and meninges protrude; spinal cord not formed properly
Spina bifida occulta - causes a cleft which is covered by the skin
What are the three primary brain vesicles that form by the fourth week
Prosencephalon, Mesencephalon and Rhombocephalon
By what week do the 5 secondary brain vesicles form?
5th week
Name the 5 secondary brain vesicles and what they form
Prosencephalon - Telencephalon (cortex), Diencephalon(thalamus and hypothalamus)
Mesencephalon - Midbrain
Rhombocephalon - Metencephalon(pons and cerebellum), Myelencephalon(medulla)
Which ventricles supply each of the 5 brain vesicles?
Telencephalon - lateral centricles
Diencephalon - third ventricle
Metencephalon - fourth ventricle
When does the surface of the brain fold?
15 weeks, major sulci formed by 28 weeks
By which week do all the neurons form?
12 weeks
What makes the brain grow after that time?
Synaptic connections - glial growth
How can you form new connections?
New ones can only be made by reorganisation
