Normal Feeding and Swallowing Development Embryological Flashcards
neuroembryology: crucial development of…
communication, cognition, and swallowing functions
neuroembryology: errors in development can lead to…
PFD, dysphagia, and multiple etiologies that result in developmental and/or feeding problems
prenatal development, embryonic period
- by 3rd week, 3 germ layers develop, CNS and cardiovascular system begin to form
- all major organ systems are formed during the 4th to 8th week of development
prenatal development, fetal period: by 24 weeks
- lungs produce surfactant 24-26 weeks: surface active lipid that maintains the opening of the developing alveoli in the lungs
- respiratory system is still very immature (usually cannot sustain life independently): surfactant therapy has helped extreme preterm infants survive in addition to other medical interventions
- period of “variability” typically discussed in preterm infants is discussed in this period of development
prenatal development, fetal period: 26-29 weeks
- lungs are capable of air exchange, but they have difficulty
- CNS is maturing
- rhythmic breathing movements are possible but not present in all infants
- beginnings of temperature control of the body
- eyes are open at the beginning of this period
prenatal development, fetal period: 30-34 weeks
- pupil response to light reflex can be elicited
- by 34 weeks white fat (nutritional reserves) make up 8% of the fetus’s body weight
- body temperature regulation is more stable by 34-35 weeks
prenatal development, fetal period: 35-40 weeks
- by 36 weeks, head circumference and abdomen are about equal (after 36 weeks abdomen circumference may be > head
- 16% of body weight is white body fat
neural tube development
- dorsal induction then occurs when the neural tube is formed and then closes (also known as primary neurulation)
- the neural plate bends upwards by the end of the 3rd week of development
- neural crest begins formation of neural tube
- complete closure of the neural tube happens by the end of the 4th week
- neural tube eventually develops the entire CNS
while it closes, it leaves neural crest cells
- are the precursors to dorsal root (sensory) ganglia for spinal and sensory cranial nerves
- precursors for Schwann cells that create myelin and the automatic nervous system
- eventually develop into the PNS
CNS development
all neurons in the spinal cord and brain are present by the 25th week of gestation
cortex develops after birth
- more dendrites more neural connections grow after birth
- results in developmental norm acquisition in the first year of life
if the neural tube doesn’t develop or close completely during these first 4 weeks of gestation the following may occur
defects of the brain, spinal vertebrae, and spinal cord
types of neural tube defects
- anencephaly
- spina bifida
- closed neural tube defects
anencephaly
- lack of development of cerebral hemispheres
- absent frontal, parietal, and occipital bones
- has anomalies in the cerebellum, brainstem, and spinal cord
anencephaly happens if the upper part of the neural tube does not close entirely
- stunts the development of the upper portion of the brain including the forebrain
- survival is typically only a few weeks
spina bifida
- can be mild to severe
- occurs in about 3 to 4 babies per 10,000 live births
mildest form of spina bifida
spina bifida occulta –> usually does not cause health problems
more severe types of spina bifida include…
- myelomeningoceles
- meningoceles
- lipomyelomeningoceles
- and other less common lesions
meningoceles
occurs when the spinal cord and nerve tissue do not protrude into the sac. lesion is usually covered by skin
myelocmeningcele
- type of “open spina bifida”
- most series form
- a portion of spinal cord and surrounding nerves protrude through an opening in the spine into an exposed, flat disc or sac that is visible on the back
- exposes the baby’s spinal cord to the amniotic fluid
- can be harmful to the baby’s fetal development
myelocmeningcele: can experience serious health problems
- hydrocephalus
- paralysis: severity of paralysis depends on where the opening occurs in the spine
hydrocephalus
an excessive accumulation of fluid in the brain
closed neural tube defects
- can be located at brain or spinal levels, but usually just the spine
- abnormality along the spine: tuft of hair growing out of a dimple of the spine
- pigmented mole
- or a lumbosacral vascular anomaly (hemangioma, port wine stain)
- lipoma
- dimple in lumbosacral region
lipoma
dome of skin with a mass of fatty tissue under it