Development of CNS
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What are the primary brain vesicles?
What are the secondary brain vesicles?
What is the derivative of the telencephalon?
What are the derivatives of the diencephalon?
- Neural portion of the pituitary gland
What is the derivative of the mesencephalon?
What are the derivatives of the metencephalon?
What is the derivative of the myelencephalon?
What are the brain flexures during development?
- Midbrain (only one to persist)
Name the components of the ventricular system.
- Fourth ventricle
- Third ventricle
- Lateral (1&2) ventricles
- Cerebral acqueduct
- Interventricular foramina
- Lateral apertures (foramina of Luschka)
- Median aperture (foramen of Magendie)
Where is the 4th ventricle?
surrounded by myencephalon (medulla obongata) and metencephalon (pons and cerebrum)
Where is the 3rd ventricle?
surrounded by diencephalon
Where is the cerebral aqueduct?
surrounded by mesencephalon; connects 3rd and 4th ventricles, behind pons
Where are the lateral ventricles?
surrounded by telencephaloic hemispheres; between cerebral hemispheres
What do the lateral apertures and median aperture do?
openings in the region of fourth ventricle which allows CSF to flow from ventricular system to subarachnoid space
What is internal hydrocephalus?
(noncommunicating) enlgmt of all or part of ventricular system due to obstruction of brain; most likely due to obstruction of the brain
What is external hydrocephalus?
(communicating) due to obliteration of subarachnoid cisterns or malfunction of subarachnoid granulations
Pyramids of medulla
part of medulla oblongata; arise from myelencephalon; develop in marginal zone
Relationship btw mesencephalon and basal/alar plates
- Alar: lie dorsal to basal. Most likely arrangement in spinal cord.
- -give rise to paired superior colliculi (visual reflexes) and paired inferior colliculi (relay of auditory info)
Crus cerebri and mesencephalon relationship
crus cerebri are important tracts which form in the marginal layer
hypothalamic sulcus: not actually a sulcus bc does not separate alar from basal
forms neural portion of pituitary gland (other portion formed from Rathke's pouch-surface ectoderm of stomodeum)
cerebral vesicles "overlap" diencephalon, mesencephalon, and part of rhombencephalon
derivatives develop into a "C" shape
cerebral cortex: consists of 3 layers of neural tube, int zone cells migrate to marginal zone cells and give rise to cortical layers so that gray matter is on outside
Spina bifida occulta
defect in vertebral arch only and assoc w/ no neurological defects; occurs in L5 or S1 in 10% population
Spina bifida cystica
- defect in vertebral arches through which protrudes meninges and/or neural tube
- 1. SB w/ meningocele
- 2. SB w/ meningomyelocele
- 3. SB w/ myeloschisis
improper closure of rostral (anterior) neural pore and therefore abnormal dev of forebrain primordium; defective calvaria dev and nervous tissue undergoes degeneration
assoc w/ excess of amniotic fluid-fetus lacks swallowing control
defect in cranium through which protrudes meninges containing CSF
defect in cranium w/ herniation of meninges and part of brain
most common; herniation of parts of medulla and cerebellum through foramen magnum into vertebral canal....communicating hydrocephalus
sm posterior cranial fossa
When does the neural plate develop? Where is it? What does it give rise to? What was it induced BY?
Embryonic ectoderm anterior to primitive knot
neural tube and neural crest
underlying notochord (nucleous pulposa) and paraxial mesoderm (somites)
When does the neural tube form? Where does it begin? What does it become?
End of 3rd and beginning of 4th wks
begins at cervical region of embryo and proceeds cranially AND caudally
ultimately becomes brain and spinal cord (sets up basic structure of wall and lumen)
*note: think "gumby" stage from lec
When does the anterior neuropore close?
*note: persists in adult as lamina teminalis
When does the posterior neuropore close?
*note: INITIALLY both posterior and anterior ends of tube are open...sig? amniotic cavity INITIALLY open to neural tube
Neural crest derivatives
- Dorsal root ganglia
- Cranial sensory ganglia
- Sympathetic chain ganglia
- Prevertebral sympathetic ganglia
- Parasympathetic autonomic ganglia
- Schwann cells of PNS
- Capsule cells on cell bodies of spinal ganglia
- Chromaffin cells (adrenal medulla)
- Skeletal struct from pharyngeal arches
- Portion of teeth
- Cells of pia and arachnoid
What are the three zones of the neural tube?
- 1. Ventricular
- 2. Intermediate (mantle): gray
- 3. Marginal: white (bc myelinated!!!)
What can glioblasts become?
- 1. Oligodendrocytes: myelination of axons in CNS (hence NOT from neural crest)
- 2. Astrocytes: transport nutrients (hence long processes)
- 3. Ependymal cells: last to dev
Alar plates (about)
assoc w/ sensory func
Balar plates (about)
assoc w/ motor func
State the changes of the spinal cord vs vertebral column.
- 6 mos fetus: S1
- baby: L3
- Adult: btw L1 and L2
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