Neuroembryology ppt 8 Flashcards
How is the neural tube formed?
Formed as the neural folds fuse in the midline and separate from the surface ectoderm
What does the neural tube give rise to?
the CNS
- The cranial part becomes the brain. brainstem
- The caudal part becomes the spinal cord.
What forms from the cavity of the neural tube?
the central canal of the spinal cord and the ventricles in the brain
When do the opening in the neural tube close?
- Anterior neuropore: closes in the fourth week (day 25) and becomes the lamina terminalis.
- Posterior neuropore: closes in the fourth week (day 27).
What does the basal plate become?
Ventral Horn MOTOR neurons
ventral gray columns, nut of CN XI
What does the the alar plate become?
Sensory dorsal horn
dorsal gray columns
What are the neural crest cells?
- Derived from ectodermal cells.
- migrate and give rise to multiple adult derivatives
What are the primary vesicles of the brain?
Forebrain (prosencephalon)
Midbrain (Mesencephalon)
Hindbrain (rhombencephalon)
What secondary vesicles derive from the Prosencephalon?
Telencephalon
Diencephalon
What adult derivative comes from the telencephalon
Tissue- Cerebral hemispheres
Cavity- Lateral ventricles
What are the adult derivatives of the diencephalon?
Tissue- Thalamus and hypothalamus
Cavity- most of the 3rd ventricle
What are the secondary vesicles of the mesencephalon?
What are the adult derivatives?
Mesencephalon
Tissue- Midbrain
Cavity- Aqueduct
What are the secondary vesicles of the rhombencephalon?
Metencephalon
Myelencephalon
What are the adult derivatives of the metencephalon?
Tissue- Pons and Cerebellum
Cavity- 4th ventricle
What are the adult derivatives of the myelencephalon?
Tissue- Medulla
Cavity- 4th ventricle
What divides the basal and alar plates?
Sulcus Limitants
When does myelination occur?
wk 28- end of adolescence
Failure of Rostral neuropore to close leads to
anencephaly
Failure of caudal neuropore to close leads to
spina bifida
Failure of the neural folds to form leads to
rachischisis
Failure of the neural tube to close at the cranial end, with lack of brain formation is
cranioschisis
What is a marker for neural tube defects?
Elevated maternal serum alpha-fetoprotein (MSFAP)
What does a decreases MSAFP indicate?
Down syndrome
What are the 4 types of spina bifida?
- Occulta
- Meningocele
- Meningomyelocele
- Myeloschisis
What is characteristic of Spina bifida occulta
A defect in the vertebral arche. no herniation. tuff of hair
What is characteristic of Spina bifida meningocele?
vertebral defect forming a sac filled with CSF.
NO metal retardation
What is characteristic of Spina bifida meningomyelocele?
meninges and spinal cord project through a vertebral defect
usually present in arnold–chiari malformation.
What is characteristic of Spina bifida myeloschisis?
The most severe, Results in an open neural tube that lies on the surface of the back.
What is anencephaly?
consists of partial or complete absence of the brain. severe failure of the anterior neuropore to close at about day 25 of gestation.
elevated AFP, Polyhydraminos, associated with maternal type 1 diabetes.
NOT compatible with life.
What is en encephalocele?
- sac-like protrusions of the brain through openings in the skull. which constitutes a failure of portions of the anterior neuropore to close.
- mental retardation and corticospinal tract dysfunction
What most likely causes enecephalocele?
Teratogens
Failure of midline cleavage of the forebrain is
holoprosencephaly
What are the main associations with holoprosencephaly?
- severe fetal alcohol syndrome
- Patau’s syndroine (trisomy 13)
- Cleft palet
- Cyclopia
What is microcephaly?
congenital malformation resulting in smaller than normal head size
occipitofrontal circumference less than the third percentile, based onstandard growth charts for sex, age, and gestational age at birth.
What risk factors for microcephaly?
Infection
Alcohol
Zika
What is Arnold-Chiari syndrome?
Herniation of the cerebellum through the foramen magnum.
Type I malformation- the most common. Often diagnosed in adulthood. Asymptomatic childhood.
Type II malformation-More severe. lumbar myelomenigocele. symptomatic in infancy or early childhood.
Type III malformation-incompatible with life.
What are the clinical symptoms of AC type II?
- Difficulty swallowing
- Loss of pain/temperature sensation along the back of the neck and shoulders.
- Mental retardation
- **Hydrocephalus due to occlusion of CSF flow- at the foramen Magnum.
What is SYRINGO(HYDRO)MYELIA?
Development of a fluid-filled cyst (syrinx) filled with CSF in the region of the central canal, which damages the crossing fibers of the spinothalamic tract, the net effect of which is to cause segmental loss of pain and temperature.
SHAWL*
What is Dandy Walker Syndrome?
Dandy can’t Walk.
No or small cerebellar vermis.
Dilated fourth ventricle, Water on the brain, Small vermis
What are causes of Dandy Walker?
What are clinical features?
- caused by viruses, posterior fossa trauma, or vitamin B2 deficiency.
- Clinical features :Severe mental retardation and ataxia.
What are risks for congenital anomalies?
Malnutrition (folic acid)
SYPHILIS
RUBELLA
Where is the choroid plexus derived from?
Roof plate
