Pathology 🩺 Flashcards
what does CNS develop from?
neuroectoderm
steps of development of the CNS
The neural plate (thickening of the ectodermal layer) → neural folds with a neural groove in between → neural tube → ventricular system, brain and spinal cord.
anatomy of the CNS
The central nervous system (CNS) includes:
- The brain and the spinal cord with their meningeal coverings (meninges).
- The rain is Protected by the cranium (Skull)
- The spinal cord is protected by the vertebral column
what are the meninges?
3 membranous layers
1. Dura mater
2. arachinoid mater
3. Pia mater
histology and origin of Dura Mater
Thick connective tissue [C.T.], mesenchyme-derived
histology and origin of arachinoid matter
Delicate C.T., have arachnoid granulations, neural crest-derived
anatomy and origin of pia matter
Adherent to the brain surface, richly vascularized, neural crest-derived
histology of the CNS
Neurons
Glial cells (neuroglia): (4 types)
1. Ependymal cells
2. Microglia
3. Oligodendrocytes
4. Astrocytes
what are the main functions of CNS cells?
Etiology of congenital CNS malformations
- Unknown
- Genetic factors
- Environmental factors: Teratogens (e.g., chemicals, infectious
- Maternal conditions: Folic acid deficiency early in pregnancy, alcoholism.
categories of congenital CNS malformations
I. Neural tube defects
II. Forebrain malformations
III. Posterior fossa malformations
IV. Spinal cord malformation
what is a neural tube defect?
- Failure of a part of the neural tube to close →malformations involving: neural tissue, meninges, and overlying bone or soft tissues.
types of neural tube defects
It may be Spinal (more common) or Cranial.
incidence of neural tube defects
Most frequent CNS malformation.
risk factors of neural tube defects
Maternal folic acid deficiency or defective enzymes involved in folic acid metabolism.
recurrence rate of neural tube defects
about 4% to 5% in subsequent pregnancies.
what is used to screen neural tube defects?
Maternal serum level of alpha-fetoprotein (MSAFP) is used to screen neural tube defects (elevated).
what region is Affected in spinal neural tube defects?
Affects the lumbo-sacral region (mostly S1 to S2).
what are the types of spinal neural tube defects?
- Spina bifida occulta
- Meningocele
- Myelomeningocele
characters of spina bifida occulta
- A bone gap of the vertebral spine
- other layers are normal
- no opening on the back.
- Associated with moles, angioma, lipoma, and a hair patch over the affected area.
what is the least severe type of spinal neural tube defects?
Spina bifida occulta
symptoms of spina bifida occulta
Very few cases have symptoms as bowel or bladder dysfunction, back pain, leg weakness or scoliosis.
characters of meningocele
- The meninges are protruded through the bone opening forming a CSF-filled sac.
- In most cases, the spinal cord and the nerves are normal or not severely affected.
what is the most rare type of spinal neural tube defects?
Meningocele