3. Development of the Nervous System

• From what structure does the nervous system develop?

  The nervous system develops from the neural tube.
• What are the three layers of the embryo and their functions?

  • Endoderm: Innermost layer, forms many organs.
  • Mesoderm: Middle layer, forms muscle and skeleton.
  • Ectoderm: Outer layer, forms nervous system and skin.
• At what point in development does the neural tube form?

  The neural tube develops at about 22 days post gestation.
• What happens to the ectoderm layer during neural tube development?

  The ectoderm thickens into the neural plate, which then folds to create a groove.
• What does the groove formed during neural tube development become?

  The groove closes and becomes the epidermis.
• What does the neural tube form in the nervous system?

  The neural tube forms the central nervous system.
• What does the neural crest form?

  The neural crest forms the peripheral nervous system.
• What is a neural tube defect?

  A neural tube defect occurs when the neural tube does not close properly.
• What is one of the most common neural tube defects?

  Spina Bifida is one of the most common neural tube defects.
• What are the three main types of Spina Bifida and their characteristics?

  • Occulta: Mildest type, 1 or 2 vertebrae affected, often asymptomatic.
  • Meningocele: Meninges protrude, spinal cord develops normally, surgery usually safe.
  • Myelomeningocele: Most severe, several vertebrae affected, spinal cord and meninges protrude.
• What are the symptoms of Spina Bifida?

  • Movement Issues: Weakness or paralysis in lower limbs, movement problems.
  • Bladder & Bowel Problems: Urinary incontinence, UTI, kidney problems.
  • Cognitive Issues: Hydrocephalus, short attention span, difficulty in problem-solving.
• What is a risk factor according to the World Health Organisation?

  A risk factor is any attribute that increases the likelihood of developing a disease or injury.
• What are some risk factors for Spina Bifida?

  Risk factors include being white, female, having uncontrolled diabetes, maternal obesity, and folate deficiency.
• What occurs during the primary differentiation of the neural tube?

  The neural tube curls and forms three bulbous regions:

  • Prosencephalon (Forebrain)
  • Mesencephalon (Midbrain)
  • Rhombencephalon (Hindbrain)
• What happens during the secondary differentiation of the neural tube?

  Prosencephalon (Forebrain) divides into:

  • Telencephalon
  • Diencephalon

  Mesencephalon (Midbrain) remains

  Rhombencephalon (Hindbrain) divides into:

  • Metencephalon
  • Myelencephalon
• What structures are formed from the telencephalon and diencephalon?

  • Telencephalon: Forms the cerebrum.
  • Diencephalon: Forms the eye cup, thalamus, hypothalamus, and epithalamus.
• What structures are formed from the metencephalon and myelencephalon?

  • Metencephalon: Forms the pons and cerebellum.
  • Myelencephalon: Forms the medulla oblongata.
• How does the spinal cord develop from the neural tube?

  • The spinal cord divides into:
  • Alar plate (dorsal horns)
  • Basal plate (ventral horns)