Week 1:2 Flashcards
3 stages of development in utero
- pre-embryonic
- embryonic
- fetal
pre-embryonic stage
conception to day 14
embryonic stage
day 15 to end of week 8
fetal stage
week 8 to birth
ectoderm becomes
- neurons and skin
- gives rise to nervous system
endoderm becomes
some internal systems and linings of tracts
When must the neural tube close?
between days 14 and 28
What is taken to prevent spina bifida?
folic acid
When does the neural plate form?
day 16
When does the neural tube form?
day 18
What happens on day 21?
- neural tube almost closed
- development of neural crest
How does the neural tube form?
top down
Where do the neural folds fuse?
at the cervical spinal cord
Day 24 significance
- top closes
- development of primary vesicles
Day 28 significance
bottom closes
What do primary vesicles give rise to?
parts of the nervous system
- prosencephalon
- mesencephalon
- rhombencephalon
What does the prosencephalon give rise to by week 6?
- telencephalon
- diencephalon
What does the telencephalon eventually become?
- cerebral hemispheres
- lateral ventricles
What does the diencephalon eventually become?
- thalamus
- hypothalamus
- retina
- third ventricle
What does the mesencephalon become?
- midbrain
- cerebral aqueduct (aka fourth ventricle)
What is the midbrain part of?
brainstem
What does the rhombencephalon become by week 6?
- metencephalon
- myelencephalon
What does the metencephalon become?
- pons
- cerebellum
What does the myelencephalon become?
medulla
What do the metencephalon and the myelencephalon help to form?
fourth ventricle
What occurs with failure of the neural tube to close?
morphogenesis
failure of closure of ANTERIOR (rostral) neuropore
anencephaly
anencephaly
- large portions of scalp, cranial bones, and cerebral hemispheres are absent
- most die in utero, virtually all by first postnatal week, very few survive
failure of closure of POSTERIOR (caudal) neuropore
spina bifida
two types of spina bifida
- oculta
- cystica
spina bifida oculta
- virtually no clinical signs
- tuft of hair on lumbar region
spina bifida cystica
herniation through the vertebral area
2 forms of spina bifida cystica
- spina bifida with meningocele
- spina bifida with myelomeningocele
spina bifida with meningocele
- herniation of the meninges, but no neural structures through the vertebral defect
- may be without symptoms
spina bifida with myelomeningocele
protrusion of both the spinal cord and meninges
symptoms of spina bifida with myelomeningocele
- saddle anaesthesia
- paralysis of bladder and bowel sphincters
- paralysis of lower limbs
When is the CNS the most susceptible to major malformations?
between day 14 and week 20
implications of developmental disorders
- growth and remodeling continue, but later insults can cause functional disturbances and/or minor malformation
hydrocephalus
- excessive buildup of CSF
- compression of brain and expansion of skull due to increased intracranial pressure
What might cause excessive buildup of CSF?
- blockage of foramen
- primary condition or secondary to other disease
treatment of hydrocephalus
drained by surgically implanted shunts
cerebral palsy
non-progressive motor disorder of prenatal, during childbirth, or shortly after birth
What are more cases of cerebral palsy due to?
stroke or anoxia from complications of pregnancy (infection, poor nutrition, late pregnancy, prematurity)
How is cerebral palsy classified?
by motor dysfunction (even if with problems of sensation, cognition, or language
types of cerebral palsy
- spastic
- dyskinetic
- ataxic
part of brain involved: spastic
cerebral cortex
part of brain involved: dyskinetic
basal ganglia
part of brain involved: ataxic
cerebellum
How is spastic CP classified?
by the extent of impairment
types of spastic CP
- hemiplegic
- diplegic
- quadriplegic
hemiplegic spastic CP
one side affected
diplegic spastic CP
both LE affected
quadriplegic spastic CP
all limbs affected
focus of treatment for CP
- improving functional abilities
- reducing impairments
PT: stretching to improve ROM, prevent contractures, developing WB
MD: reducing spasticity with drugs or surgery
What does the notochord do?
helps form the vertebral column
What do somites form?
most of the skull, spinal column, and supporting structures (surrounding skeletal muscles, segmentation of spinal cord)
spina bifida correction
correctible with surgery, but spina bifida with myelomeningocele may have motor delays
What does cerebral palsy largely affect?
motor cortex
spasticity
continued contraction of muscles
dyskinetic
problems with voluntary movement and motor planning
What are contractures caused by in people with cerebral palsy?
spasticity
