Neurology And Special Senses Flashcards
Notochord induces overlying ectoderm to differentiate into ———
And form ———.
1. Neuroectoderm
2. Neural plate
Notochord becomes ——— in adults.
Nucleus pulposus of intervertebral disc
Neural plate gives rise to:
Neural tube and neural crest cells
Lateral walls of neural tube are divided into:
Alar and basal plates
What are the functions and locations of the alar and basal plates, and what are they induced by?
Alar plate (dorsal): sensory; induced by bone morphogenetic proteins (BMPs)
Basal plate (ventral): motor; induced by sonic hedgehog (SHH)
(Same orientation as spinal cord)
Three primary vesicles of neural tube:
1. Forebrain (prosencephalon)
2. Midbrain (mesencephalon)
3. Hindbrain (rhombencephalon)
Five secondary vesicles of neural tube (and primary vesicles they come from):
Forebrain (prosencephalon):
1. Telencephalon
2. Diencephalon
Midbrain (mesencephalon) :
3. Mesencephalon
Hindbrain (rhombencephalon):
4. Metencephalon
5. Myelencephalon
Walls that are adult derivatives of neural tube (and primary/secondary vesicles they come from):
Forebrain (prosencephalon)/ Telencephalon:
1. Cerebral hemispheres
2. Basal ganglia
Forebrain (prosencephalon)/ Diencephalon:
3. Thalamus
4. Hypothalamus
5. Retina
Midbrain (mesencephalon)/ Mesencephalon
6. Midbrain
Hindbrain (rhombencephalon)/ Metencephalon:
7. Pons
8. Cerebellum
Hindbrain (rhombencephalon)/ Myelencephalon:
9. Medulla
Cavities that are adult derivatives of neural tube (and primary vesicles they come from):
Forebrain (prosencephalon):
1. Lateral ventricle
2. Third ventricle
Midbrain (mesencephalon) :
3. Cerebral aqueduct
Hindbrain (rhombencephalon):
4. Fourth ventricle
Neuroepithelia in neural tube origins for:
CNS neurons and CNS glial cells (astrocytes, oligodendrocytes, ependymal cells)
Neural crest origins for:
PNS neurons (dorsal root ganglia, autonomic ganglia [sympathetic, parasympathetic, enteric]), PNS glial cells (Schwann cells, satellite cells), and adrenal medulla
Mesoderm origin for what CNS glial cell?
Microglia (like macrophages).
Definition for neural tube defects:
Failure of neural tube to close completely by week 4 of development
Neural tube defects associated with ——— during pregnancy
Maternal folate deficiency
Neural tube defects diagnosed by:
Ultrasound,
Maternal serum alpha-fetoprotein (AFP) (increased in open NTDs)
List major open and closed neural tube defects:
Closed NTDs:
Spina bifida occulta
Open NTDs:
Meningocele
Myelomeningocele
Myeloschisis
Anencephaly
Spina bifida occulta characterization, location, and associated symptoms:
Characterization:
- Failure of caudal neural tube to close, but no herniation
- Dura is intact
Location:
- Usually seen at lower vertebral levels
Associated Symptoms:
- Tuft of hair or skin dimple at level of bony defect
Meningocele characterization:
- Meninges (but no neural tissue) herniate through bony defect
- Skin defect/thinning
Myelomeningocele characterization:
- Meninges and neural tissue (eg, cauda equina) herniate through bony defect
- Skin thin or absent
Myeloschisis characterization:
Exposed, unfused neural tissue without skin/meningeal covering
Anencephaly characterization and presentation:
Characterization:
- Failure of rostral neuropore to close
- No forebrain, open calvarium
Presentation:
- Polyhydramnios (decreased fetal swallowing due to lack of neural control)
Holoprosencephaly characterization, occurrence time, associated mutation, associated conditions, and presentation:
Characterization:
- Failure of forebrain (prosencephalon) to divide into 2 cerebral hemispheres
Occurrence Time:
- Developmental field defect usually occurring at weeks 3–4 of development
Associated Mutation:
- SHH mutation
Associated Conditions:
- Patau syndrome (trisomy 13)
- Fetal alcohol syndrome
Presentation: (Midline defects)
- Monoventricle
- Fused basal ganglia
- Cleft lip/palate
- Hypotelorism
- Cyclopia
- Proboscis
- Risk for pituitary dysfunction (eg, diabetes insipidus)
Lissencephaly characterization and presentation:
Characterization:
- Failure of neuronal migration
- Smooth brain surface that lacks sulci and gyri
Presentation:
- Dysphagia
- Seizures
- Microcephaly
- Facial anomalies
Do neurons divide in adulthood?
No
Permanent cells—do not divide in adulthood
What part of neurons receives input and what part sends output?
Dendrites receive input and axons send output
What does Nissl staining stain, and which part of neurons visible on Nissl stain?
Nissl staining stains RER
Cell bodies and dendrites can be seen on Nissl staining (RER is not present in the axon)
Neuron markers:
neurofilament protein and synaptophysin
Largest and most abundant glial cell in CNS?
Astrocytes
Astrocytes derived from:
Neuroectoderm
Astrocyte marker:
GFAP
6 functions of Astrocytes:
- Physical support
- Repair
- Removal of excess neurotransmitter
- Component of blood-brain barrier
- Glycogen fuel reserve buffer
- Reactive gliosis in response to neural injury
——— fuse to form multinucleated giant cells in CNS in ———
- HIV-infected microglia
- HIV-associated dementia
Microglia are———— with activation in response to———, leading to release of———
- Phagocytic scavenger cells of CNS
- Tissue damage
- Inflammatory mediators (eg, nitric oxide, glutamate)
Microglia apperence on Nissl stain:
Not readily discernible
Describe appearance and location of Ependymal cells:
Appearance:
- Ciliated simple columnar glial cells
Location:
- Lining ventricles and central canal of spinal cord
Apical surfaces of ependymal cells are covered with ——— (which ———) and ——— (which help with ———)
- Cilia (which circulate CSF)
- Microvilli (which help with CSF absorption)
Specialized ependymal cells (location:———) produce ———
- Choroid plexus
- CSF
Ependymal cells derived from:
Neuroectoderm
Function of myelin:
Increases conduction velocity of signals transmitted down axons