Developmental Flashcards
Notocord does
Induces overlying ectoderm to differentiate into neuroectoderm and form the neural plate by day 21
And notochord becomes nucleus pulposus of the intervetebral discs
Neural plate gives rise to
The neural tube and neural crest cells
Alar plate
Dorsal neural tube: give rise to sensory
Basal plate
Ventral neutral tube: motor
Regional specificiation
Forebrain: prosencephalon
Midbrain: mesencephalon
Hindbrain: rhomboencephalon
Prosencephalon becomes
1) telecephalon; cerebral hemishere and lateral bentricle
2) diencephalon: thalamus and third ventricle
Mesencephalon becomes
Midbrain and aqueduct
Rhombencephalon
1) Metencephalon: pons cerebellum and upper part of 4th ventricle
2) myelencephalon: medulla and lower part of the 4th ventricle
When and what to find in neural tube defect
Fail to fuse by 4th week
Increased AFP in aminionic flud and maternal serum
Also increased AChE in aminiotic fluid.
Spina bifida occult
Failure of bony spinal canal to close, but no structural herniation+ tuft of hair or skin dimpling at the level of bony defect
Meningocele
Meninges but not the spinal cord herniate through the spinal canal defect
Meningomyelocele
Meninges and spinal cord herniate through spinal canal defect
Forebrain abnormalities: anencephaly
Malformation of anterior neural tube resulting in no brain, open calvariumm (frog like appearance)
Increased AFP, polyhydramniosis
Associated material diabetes,
Reduced risk with folate supplementation
Forebrain abnormalities: holoprosencephaly
Failure of left and right hemispheres to separate
Usually during wks 5-6
Complex multifactorial etiology that related to Shh
Moderate form has cleft lip/palate, most severe in cyclopia.
Posterior fossa: Chiari II
Arnold Chiari malformation
Cerebellar tonsillar and verminan herniation through foramen magnum with aqueductal stenosis and hydrocephalus
Often presents with thoraco-lumbar myelomeningocele and paralysis below the defect
Posterior fossa: Dandy Walker
Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills the enlarged posterior possa)
Associated with hydrocephalus and spina bifida.
Syringomyelia
Central cord syndrome
Cystic enlargement of central canal of spinal cord
Cross fibers of spinothalamic tracts typically damaged first
“capek like” bilateral loss of pain and temp sensation in upper extremities (fine touch sensationreserved)
Associated with Chiari I malformation (>3-5 mm crebellar tonsiler ectopia)
Most common atC8-T1
Tongue development
Anterior 2/3: 1st branchial arch, sensation via CN5 mandible 3, taste via CN 7.
Poster 1/3: 3rd and 4th arches. sensation and taste mainly via CN 9, and extreme posterior via CN 10
Motor innervation via CN 12, muscles of tones derived from occipital myotomes, except for palatoglossus by CN10
