Development of the Brain Flashcards
When does the brain develop?
During the 3rd week
What does the brain develop from?
From the neural tube, cranial to 4th pair of somites
How do the primary brain vesicles form?
Fusion of neural folds in cranial region and closure of rostral/cranial neuropore
What are the primary brain vesicles?
Forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon)
What secondary vesicles does the prosencephalon give rise to?
Telencephalon and diencephalon
What secondary vesicles does the mesencephalon give rise to?
Mesencephalon
What secondary vesicles does the rhombencephalon give rise to?
Metencephalon and myelencephalon
What does the telencephalon give rise to?
Cerebral hemispheres and lateral ventricles
What does the diencephalon give rise to?
Thalami (hypothalamus, epithalamus, thalamus) and 3rd ventricle
What does the mesencephalon give rise to?
Midbrain and aqueduct
What does the metencephalon give rise to?
Pons and cerebellum and upper part of 4th ventricle
What does the myelencephalon give rise to?
Medulla and lower part of 4th ventricle
What causes brain folding/flexures?
Unequal proliferation in different brain vesicles
What is the first flexure to fold?
Midbrain flexure (mesencephalic flexure). Flattening/face down forward motion of telencephalon and diencephalon at junction with mesencephalon
What is the second flexure to fold?
Cervical flexure. Forward bending at hindbrain/spinal cord junction creates positioning of brainstem underneath brain
What is the third flexure?
Pontine flexure. Folds backward at metencephalon/myelencephalon junction. Positions cerebellum over/posterior to pons
What forms in the caudal myelencephalon?
Nuclei gracilus and cuneatus (from alar plate)
Pyramids (basal plate)
What forms in the rostral myelencephalon?
Alar plates (sensory/afferent inputs) and basal plates (motor/efferent outputs)
How does the pontine flexure move the alar and basal plates?
Alar plate moves lateral to basal plate
Neuroblasts in the basal plate develop into what?
Efferent neurons
Neuroblasts in the alar plate develop into what?
Afferent neurons
How are the olivary nuclei formed?
Alar neurons migrate anteriorly
How does the cerebellum develop?
From the dorsal parts of alar plates. Cerebellar swellings arise which fuse over the median plate, overgrowing the posterior side of the 4th ventricle