Fetal Development Flashcards
Importance of Neuroembryological Development
crucial for development of comunication, cognition, and swallowing functions
Errors in Neuroembryological Development lead to..
- Pediatric feeding disorders
- dysphagia
Factors that Interrupt Development
- Teratogens (substances causing harm), like viruses and toxins
- Adverse events, like premature birth, trauma, chronic illness, environmental factors
Physical Impacts of Interrupted Development
inadequate growth (failure to thrive)
swallowing dysfunctions leading to aspiration or malnutrition
Cognitive Impacts of Interrupted Development
delayed speech and language acquisition
impaired problem-solving and social skills
Psychological Impacts of Interrupted Development
feeding aversions and behavioral challenges
increased caregiver stress and family burden
Pre Embryonic Development
lasts from fertilization to two weeks
includes fertilization of sperm to form zygote
zygote undergoes rapid mitotic divisions, forming blastocyst
blastocyst imbeds in uterus
formation of basic structures
Significance of Pre-Embryonic Development
establishes foundation for development of all body systems
Embryonic Development Time Frame
week 3 to week 8
Embryonic Development Key Events
- gastrulation: formation of three germ layers (ectoderm, mesoderm, endoderm)
- Organogenesis: development of major organs and systems, including neural tube, heart, and limb buds and basic facial features
Ectoderm
forms nervous system, skin, and sensory organs
Mesoderm
Develops into muscles, bones, circulatory system, and other internal structures
Endoderm
forms digestive and respiratory systems
Vulnerability of Embryonic Development
high sensitivity to teratogens
Significance of Embryonic Development
critical for establishing structural foundation of body
Neural Tube Development (neurulation)
Around day 18, ectoderm begins to thicken to create neural plate between cranial portion and primitive node. Day 19 buckles at midline to create neural groove with neural folds on the sides. The folds fuse together around day 21. They form the neural tube. Should fuse from cranial to caudial ends. Cranial and Caudial Neuropores (the ends) fuse last (cranial day 24 and caudial day 26). Neural crest cells are at the peaks of the neural folds and they form a layer over the neural tube. They make up most of the Peripheral Nervous System. Neural Tube makes up Central Nervous System
Neural Tube Timeline
Neural Plate bends upward by end of 3rd week
Completed by end of 4th week
Dorsal induction occurs when neural tube is formed and closed
Neural Crest Cells
are the precursers to dorsal root (sensory) ganglia and sensory cranial nerves
Precursers for Schwann Cells that create myelin and autonomic nervous system
eventually develop into PNS
CNS Development
All neurons in brain and spinal cord are present by 25wks gestation
Cortex continues to develop after birth (more dendrites more neural connections grow after birth) results in acquisition norm for 1st year of life
Errors in Neural Tube Development
if doesn’t close fully by 4 wks, may see
1. deficits of the brain
2. deficits of spinal cord
3. deficits of spinal vertabrae
Anencephaly
a neural tube defect
lack of development of cerebral hemispheres, absent frontal, parietal, and occipital bones
anomalies in cerebellum, brainstem, spinal cord
occurs if upper part of tube doesn’t close
stunts development of the upper portion of the brain
Spina Bifida
caused from a spot that doesn’t fuse on neural tube
can be mild to severe
Pharyngeal Arches/branchial arches
embryos have 5 pairs that give rise to face, jaw, ear, and neck
numbered 1-6 (cause 5 is not always present/doesn’t do anything)
errors here result in craniofacial development errors
Pharyngeal Arch Development Week 4
they appear around week 4 of development
neural crest cells migrate into the arches
Pharyngeal Arch Development Week 5-6
pharyngeal arches become more defined and basic structures start to form
arches 1,2,3 are clearly visible and begin developing arteries, muscles, and cartilage
1st arch forms maxilla, manible, and muscles of mastication start to differentiate
Pharyngeal Arch Development Week 6-7
2nd arch forms the stapes and parts of hyoid bone
muscles of facial expression and other structures associated with 2nd arch start forming
3rd arch begins forming greater horn of hyoid bone and muscles involved in swallowing
Pharygneal Arch Development Week 7-8
The fourth arch develops and forms laryngeal cartilages and muscles in larynx
5th arch regresses but forms laryngeal muscles
6th arch continues to contribute to laryngeal structures and muscles
Pharyngeal Arch Development by Week 8
major cartilages, muscles, and nerves of pharyngeal arches are established
primary strucutres of head and neck start to take shape
Pharyngeal Arch Development Importance to Feeding and Swallowing
proper development ensures that the muscles and cranial nerves required for oral feeding are functional. Vital for infant feeding and later for solid food introduction and speech
disruptions can lead to feeding difficulties (problems chewing, swallowing, airway protection)
can result in craniofacial anomalies which affect feeding
affect cranial nerves involved in swallowing or diffictulies in oral-motor skills
Pharyngeal Arch 1 Develops….
1) maxillary artery
2) trigeminal nerve
3) muscles of mastication: mylohyoid, anterior belly of digastric, tensory tympani, tensory veli tympani
4) mandible, maxilla, malleus, incus, zygomatic and temporal bones
