Embryology Of The Head, Face & Oral Cavity Flashcards
Embryology
Study of the development of tissues
Oral embryology
The study of development of oral tissues
Embryogenesis
Process of embryological development, forming of tissues and organs.
Embryonic origins
3 tissue layers of tri-laminar embryonic disk that give rise to all tissues in the body.
(Ectoderm
Mesoderm
Endoderm)
Derivatives
Structures that the origins/tissue layers form
3 embryonic origins
Ectoderm
Mesoderm
Endoderm
3 key phases of embryogenesis and development
Early embryogenesis (weeks 1-4)
Embryogenesis (weeks 5-8)
Fetal development (week 9-birth)
Where does the connective tissue in head, face and oral cavity derivatate from
Ectoderm - neuroectoderm - neural crest cells - ectomesenchyme
Key stages of early embryogenesis
Fertilisation
Cleavage
Proliferation
Migration
Differentiation
What forms in 2-3 weeks of early embryogenesis, when the embryoblast within the blastocyst proliferations and changes
Blaminar embryonic disc
Ectoderm
Endoderm
Trophoblast
Cell lining the blastocyst
Blastocoel
Primary fluid filled space within blastocyst
Embryoblast
Cluster of cells within blastocyst
What does the bilaminar embryonic disc change into as it grows
Trilaminar embryonic disc
Ectoderm - outside
Mesoderm - middle
Endoderm - inside
What do the fold form in week 4 of early embryogenesis
Embryo starts to take shape through folds forming:
Stomodeum (primitive mouth)
Bucco-pharyngeal membrane
Primitive gut
Building blocks to the structures of the face and oral cavity
Pharyngeal arches (branchial arches)
When do the pharyngeal arches devleop
Week 4 early embryogenesis
1st pharyngeal arch
Nerve and muscles
Trigeminal nerve
Muscles of mastication
2nd pharyngeal arch
Nerves and muscles
Facial nerve
Muscles of facial expression
3rd pharyngeal arch
Nerves and muscles
Glossopharyngeal nerve
Stylopharyngeal muscle (swallowing)
4th pharyngeal arch
Nerves and muscles
Superior branch of vagus nerve
Laryngeal muscles
When does the development of head, face and oral cavity cavity occur
Embryogenesis weeks 5-8
Prominences that fuse together to form the face
1x frontonssal prominence
2x maxillary prominence
2x mandibular prominence
Embryogenesis weeks 4-6
When does the development of the primary palate occur and how
Weeks 6-7 embryogenesis
Frontonasal prominence and medial nasal prominences fuse together.
When does the development of the secondary palate occur and how
Weeks 7-8 embryogenesis.
After primary palate.
Palatine shelves grow from either side and fuse at midline and with primary palate and nasal septum.
Incisive foramen forms.
When does the development of the tongue occur and how
Week 4-7 embryogenesis.
1st, 2nd and 4th pharyngeal arches.
Development of anterior 2/3rds of tongue
Form from
2x lateral lingual swellings 1st pharyngeal arch.
Tuberculum impar 2nd pharyngeal arch.
Development of posterior 1/3rd of tongue
Forms form
Copula eminence 4th pharyngeal arch.
What has to occur to allow the tongue to separate from floor of mouth
Cellular apoptosis
Leaves frenum behind as anchor
When and how does the development of the alveolar bone occur
Week 7 embryogenesis
Maxilla and mandible jaws undergo ossification starting from maxilla and mandibular prominences.
What does each jaw develop
Neural and alveolar portion - Support the development of teeth.
Secondary cartilages - Support growth of bone throughout life.
Where do the skull bones derive from
Neural crest cells and mesoderm
3 sections of skull development
Cranial vault (brain case)
Cranial bones
Facial bones
At what age do the cranial bones fully fuse and why?
6-7 years old
Allow for brain growth and development
When does the fetal development phase occur
After the first 8 weeks
Week 9 - birth
What is the focus of fetal development
Growth of fetus.
Continuation of development and maturation of structures that have formed.
Aetiology of anomalies in embryology
- Genetic
- Environmental/congenital (infections, radiation, hormones, nutritional deficiencies, medications)
What type of abnormality is cleft lip and/or palate
Congenital anomalies.
Happens due to local cause or disruption in process.
How common is cleft lip palate
1 in 700 live births
Cleft lip
Failure of fusion of 2 medial nasal processes
and/or
Maxillary and mesial nasal processes.
Unilateral or bilateral.
Cleft palate
Failure of fusion of palatine shelves together
and/or
the nasal septum.
What do cleft lip and palate patients remain at higher risk for
Oral disease.
Impact on development of teeth.
