notochord
induces the overlying ectoderm to differentiate into neuroectoderm and form the neural plate
the notochord eventually becomes the nucleus purposes of the intervertebral disc in adults
neural plate
gives rise to the neural tube and neural crest cells
rostral part of neural tube
caudal part
becomes the adult brain
spinal chord
surface ectoderm
adenopypophysis (rathke pouch), lens of the eye, epithelial linings of the oral cavity, sensory organs of the dear and olfactor epithelium
epidermus, anal canal below the pectinate line
parotid, sweat and mammary glands
neuroectoderm (which gives rise to the neural plate –> neural tube and neural crest cells)
Think CNS
Brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina and optic nerve, spinal chord (caudal neural tube)
Neural crest derivatives
PNS!!!
-dorsal root ganglia, cranial nerves (not optic), celiac ganglion, schwann cells, ANS).
funny ones:
melanocytes, chromaffin cells of adrenal medulla, parafollicular C cells of thyroid, pia and arachnoid, bones of the skull, odontoblasts and
dont forget - aorticopulmonary septum
Forebrain (prosencephalon) –>
telencephalon –> cerebral hemispheres (walls) and lateral ventricles (cavities)
diancephalon –> thalamus and third ventricle
Midbrain (mesencephalon) –>
Mesencephalon (secondary vessicle) –> midbrain and aqueduct
Hindbrain (rhombencephalon) –>
Metencephalon –> pons and upper fourth ventricle
and the cerebellum
myelencephalon –> medulla and lower part of the fourth ventricle
neuro related mesoderm derivative
microglia (like macrophages originate from the mesoderm)
neural tube defects general
- neuroporse fail to fuse at week 4
- assoc. with low folate
- elevated a-fetoprotein (AFP) in amniotic fluid and maternal serum.
- increased acetylcholinesterase in amniotic fluid because fetal ACeE in CSF transudates across defect into the amniotic fluid)
spina bifida occulta
- failure of the BONY spinal canal to close, but no herniation
- usually lower vertebral
- dura is intact
- assoc with tuft of hair or skin dimple
meningocele
meninges (but not the spinal cord) herniate through the spinal canal defect, normal AFP
meningomyelocele
meninges and the spinal cord herniate through the spinal canal defect
anecephaly
- forebrain anomaly
- malformation of anterior neural tube results in no forebrain
- open calvarium
- increased AFP, polyhydramnios (no swallowing center in brain)
- assoc with DM 1
- give folate to reduce risk
polyhydraminos
excess amniotic fluid in sac…. rememeber baby swallows amniotic fluid
holoprosencephaly
failure of the L and R hemispheres to separate
-week 5-6
complex etiology but most likely mutations in sonic hedgehog signalling pathway
clinical: cleft lip/palate
most severe: cyclopia
Chiari II (anold-chiari malformation)
- herniation of cerebellar tonsils and vermis through foremen magnum
- with aqueductal stenosis and hydrocephalus.
- myelomeningocele may be present and paralysis below the defect
Dandy-walker
agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills the enlarged posterior fossa). Assoc with hydrocephalus and spina bifida
syringomyelia
- cystic cavity within the spinal chord (neck)
- crossing anterior spinal commissural fibers are typically damaged first.
- cape like bilateral loss of pain and temperature in upper extremities
- fine touch is preserved
- C8-T1
- assoc with Chiari I
Chiari 1
> 3-5 mm cerebellar tonsillar ectopia
- congenital
- usually asymptotic in childhood
- manifests with headaches and cerebellar symptoms
Tongue muscles are derived from?
occipital myotomes
Motor innervation of tongue?
CNXII
Taste of tongue CN?
CN VII anterior 2/3
IX posterior 1/3
and X (solitary) very back back
