embryology Flashcards
caudal part of the forebrain between the telencephalon and midbrain.
diencephalon
It consists of the hypothalamus, thalamus, epithalamus, and the subthalamus.
DIENCEPHALON
motor planning coordination
cerebellum
brainstem
vital automatic functions, such as breathing, circulation, sleeping, digestion, and swallowing - involuntary processes controlled by the ANS
The Nervous System begins formation during week ___ of ___ period
week 3 of embryonic period
formation of the early nervous system structures.
Neurulation
ectoderm creates
epidermis, nervous system, tooth enamel
mesoderm paraxial
forms somites = body segments
intermediate mesoderm
genitourinary
lateral mesoderm creates
anterolateral body wall smooth muscle and connective tissue of viscera, heart and blood vessels.
endoderm creates
epithelium of GI, Respir.; liver and pancreas
Neurons ependymal cells ( line the ventricles and make CSF) oligodendroglia and astrocytes are formed from this germ layer
neuroectoderm
PNS neurons and Schwann cells come from this germ layer
neural crest cells
the microglial is formed by this germ layer
mesoderm
_______ is the process of folding of the neural plate into the neural tube that week three during development and continues through week _____
neurulation week 4
Neural crest forms part of the ________
PNS : ganglia (sensory and ANS)
The neural tube WALL is composed of
neuroepithelium
The neural tube LUMEN will become the ____ and ____
ventricles (brain) and centra canal (spinal cord)
3 layers of the neural tube lumen
- ventricular - ependyma - glial cell lining of ventricles -intermediate - gray matter (neuron cell bodies) -marginal - white matter (axon clusters)
what does the embryonic midbrain become in development?
mesencephalon and then the midbrain/part of the brain stem
the pons develops from what
metencephalon
the cerebellum is derived from what embryonic brain region
metecephalon
medulla oblongata is derived from the embryonic
myelencephalon
3 layers/zones of neuroepethlium that develops from the neural tube:
ventricular, intermediate, marginal
the neural tube intermediate zone subdivides into ____ and ____ plates and becomes the ____ mater
alar basal gray matter
the alar plate becomes the __________ cranial nerve nuclei
sensory/afferent
the basal plate becomes the _______ cranial nerve nuclei
motor/efferent
Spina bifida, The BONY defect involves the ________________
dorsal vertebral arch
SB occulta presentation
tuft of hair, dimple)
SB cystica presentation
herniating cyst
Tubular cavitation of the spinal cord
syringomyelia
presentation of syringomyelia
-Wasting and weakness of the hand and forearm muscles -Loss of arm reflexes
age of consent of syringomyelia
2nd or 3rd decade of life
syringomyelia is frequently associated with ______ in patients with idiopathic disease
Chiari type I
Syringomyelia may also develop secondary to ________
tumor, trauma, meningitis, or hemorrhage
The basic abnormality of NTD is a defect in the overlying _____.
bone (not a defect in the neural tissues)
risk factors for neural tube defect
Maternal folic acid (B9) deficiency
screening for neural tube defects
increase in α fetoprotein (maternal blood
functional impairments of SB occulta
No functional impairments.
functional impairments of SB cystica meningocele
Paralysis below the lesion. Bowel and urinary dysfunction +/- hydrocephalus
types of SB cystica
Meningocele, Myelomeningocele, Rachischisis
Most common site for SB cystic is ______
lumbosacral
most common type of SB cystica
Myelomeningocele
Rachischsis often develops with _______.
anencephaly
Cranial Neural Tube Defects (NTD) are called
Cranium bifidum
the bony defect of cranium bifidum involves the _______
occipital bone
if the defect is large in cranium bifidum, the ________ in the brain may herniate
meninges
Most severe form of cranial NTD
Anencephaly = Meroanencephaly
in anencephaly, the_______ does NOT fuse/close in Week 4.
Cranial neuropore No neural tube forms in cranial region. No cerebrum forms. No skull forms. No skin forms.
All infants with_____ are stillborn or die soon after birth.
anencephaly
gene affected in Holoprosencephaly
HPE2: Six3 homeobox gene HPE3: SHH gene HPE5: ZIC2 gene
______ presents with midline facial defects that range from hypotelorism to cyclopia
Holoprosencephaly
As a rule of thumb, the_____ predicts the brain.
face
failure of separation of the forebrain into two cerebral hemispheres
holoprosencephaly
__________ may develop in a child if she/he is exposed to high levels of alcohol in utero.
Fetal alcohol syndrome
If exposed during weeks when the brain is forming, _________ may develop in fetal alcohol syndrome
intellectual disability
describe fetal alcohol syndrome
smooth philltrum, epicanthal folds, small eyes, flat face, thin upper lip
Herniation of a peg of cerebellar tonsil through the foramen magnum in the absence of an intracranial mass lesion or preceding hydrocephalus
chiari malformation I
chiari malformation I is strongly associated with
syringomyelia
•Combines herniation of cerebellar vermis with malformation and downward displacement of brain stem
chiari formation II
Syringomyelia
Tubular cavitation of the spinal cord
Almost always associated with lumbosacral myelomeningocele
chiari malformation II
Accompanied by hydrocephalus at birth in >80% of cases
chiari malformation II
dandy walker syndrome
- Vermal agenesis
- Cystically dilated fourth ventricle
- Enlarged posterior fossa
- Hydrocephalus
the spinal cord ends in this region
L1-L2 region
3.What other condition in present in >80% of cases with Chiari II?
hydrocephalus
