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
pharyngeal arches/branchial arches
- human embryos have 5 pairs (numbered in craniocaudal sequence): give rise to face, jaw, ears, and neck
- numbered 1-6, without 5
- errors here result in craniofacial development errors
pharyngeal arches/branchial arches: numbered 1-6, without 5
5 is a short-lived, rudimentary form or may not develop at all in human embryological development
pharyngeal arches
series of externally visible anterior tissue bands that give rise to the early structures of the head and neck
pharyngeal arch 1: artery
maxillary artery
pharyngeal arch 1: nerve
trigeminal (CN V)
pharyngeal arch 1: muscles
muscles of mastication: anterior belly of the digastric muscle, tensor tympani, tensor veli palatini
pharyngeal arch 1: skeletal structures
mandible, maxilla, malleus, incus, zygomatic and temporal bones
