IBSSD Orofacial Development PDF

L25: Orofacial Development IBSSD 1525/1513 Dr. Samuel Gutherz  Outline Briefly review pharyngeal apparatus development Explore evolutionary history of head & neck embryology Discuss the development of various head structures Face Nose & nasal cavit...

L25: Orofacial Development IBSSD 1525/1513 Dr. Samuel Gutherz  Outline Briefly review pharyngeal apparatus development Explore evolutionary history of head & neck embryology Discuss the development of various head structures Face Nose & nasal cavity Tongue Thyroid gland Palate Teeth Pharyngeal Apparatus Review Arches 1 Maxillary & mandibular structures; malleus & incus CN V Muscles of mastication 2 Muscles of facial expression Stapes, styloid process, part of hyoid Branches of ECA CN VII 3 Part of hyoid CN IX, stylopharyngeus Parts of ICA & CCA 4&6 Laryngeal cartilages CN X Pharyngeal & laryngeal muscles Pharyngeal Spaces Clefts External, ectoderm 4 pairs between arches Pouches Internal, endoderm 4 between arches 1: ear cavity, pharyngotympanic tube, tympanic membrane (with 1st pharyngeal cleft) 2: palatine fossa, palatine tonsils 3: inferior parathyroid glands, thymus 4: superior parathyroid glands, part of thyroid gland Evolutionary Origins Arches 1st appear as filter feeding apparatus Anterior arches → jaws Introduction of NCC & mesoderm Skeleton & muscles Evolutionary Origins Arches 1st appear as filter feeding apparatus Anterior arches → jaws Introduction of NCC & mesoderm Skeleton & muscles Predatory lifestyle Respiratory role of arches Reduce # of arches Evolutionary Origins Pt. 2 Movement to land (tetrapods) Evolutionary Origins Pt. 2 Movement to land (tetrapods) Closing of posterior end of pharynx (no gills) Reduce posterior arches Evolution of parathyroid gland (Ca TIME regulation) Creation of air chamber for ear Sound conduction Evolution of Mammalian Ear: Ossicles Tetrapod jaw joint – quadrate:articular Evolution of Mammalian Ear: Ossicles Mammal jaw joint – dentary: squamosal Mandible:temporal in humans Articular → Malleus Quadrate → Incus Evolution of Mammalian Ear: Ossicles Mammal jaw joint – dentary: squamosal Mandible:temporal in humans Articular → Malleus Quadrate → Incus Viscerocranium X Pharyngeal arch 1 Mandibular process – mandible, malleus, incus 1st PA: Muscles Palate Tensor veli palatini Tensor tympani Face Facial Primordia Begins at week 4 Stomodeum – mouth precursor 5 prominences Frontonasal prominence 2 maxillary prominences 2 mandibular prominences Placodes Thickened ectoderm that form sensory structures Lens - eyes Otic - ears Nasal - Nose  Week 4 Nasal Development Placode flattens, then depresses Forms horseshoe Nasal pit – nasal cavity Lateral nasal prominence – ala, nasolacrimal duct Medial nasal prominence – part of nose, philtrum, upper lip, part of palate Week 6 Nasal Cavity Week 5 Nasal pits → nasal sac Oronasal membrane Week 7 Developing palate separates nasal & oral cavities Paranasal sinuses Week 12 Late fetal development or postbirth Nasal Cavity Nasal pits → nasal sac Oronasal membrane Developing palate separates nasal & oral cavities Paranasal sinuses Late fetal development or postbirth Forehead & Nose Frontonasal prominence Medial nasal prominence Lateral nasal prominence Forehead & Nose Nasolacrimal duct Lateral nasal prominence Nasolacrimal duct Lips Upper lip Medial nasal prominences Maxillary prominences Medial nasal Cheeks prominence Lower Lip Mandibular prominences Finalizing Facial Development Paranasal sinuses Accommodation of teeth Brain enlargement Tongue Tongue Swellings Starts ~ week 4 1st pharyngeal arch 2 lateral swellings Tuberculum impar – medial swelling Hypobranchial eminence (copula) 2nd median swelling 2nd, 3rd, & 4th pharyngeal arches Epiglottal swelling 4th pharyngeal arch  Lateral swellings overgrow tuberculum impar Anterior 2/3 of tongue Posterior tongue 3rd arch tissue overgrows 2nd arch Terminal sulcus  CN XII & Muscles Hypoglossal Nerve (CNXII) Occipital Somites (OS)  2 34 1 Tongue Nerves Somatic Sensory Body – CN V Root – CN IX (little bit of CN X) Special Sensory Body – CN VII Root – CN IX Motor – hypoglossal (CN XII) Thyroid Gland Tongue Beginnings 1st endocrine gland Thickening in developmental tongue Between tuberculum impar and copula Foramen cecum  Descent Begins descent Thyroglossal duct  Descent Begins descent Thyroglossal duct Fuses with ultimopharyngeal body 4th pharyngeal pouch  Descent Finishes descent ~ week 7  Descent Begins descent Thyroglossal duct Fuses with ultimopharyngeal body 4th pharyngeal pouch Finishes descent ~ week 7 Palate Overview Palate – roof of mouth, separates oral & nasal cavities Primary palate Anterior (incisive foramina) Medial nasal prominence Secondary palate Anterior 2/3 of bony palate and soft palate Maxillary prominences Primary Palate Medial nasal prominence Merging of 2 medial nasal prominences Primary Palate Medial nasal prominence Merging of 2 medial nasal prominences Intermaxillary segment Premaxillary part of maxilla 4 incisors Separates nasal and oral cavities early in development Incisive foramina Incisive foramina Secondary Palate Palatine shelves Maxillary prominences ~Week 6 Project below tongue Secondary Palate Palatine shelves Maxillary prominences ~Week 6 Project below tongue Pull tongue into mouth Secondary Palate Palatine shelves Maxillary prominences ~Week 6 Project below tongue Pull tongue into mouth Horizontal ~week 7–8 Teeth  Bud Stage (Week 6) Primary Dentition (Placode) Deciduous teeth Oral ectoderm + mesenchyme + neural crest cells Buds or placodes form in dental lamina 10 / jaw Cap Stage (Week 9–10) Deep surface of bud invaginates Forms inner & outer dental epithelia Enamel knot Enamel Enamel organ Stellate reticulum  Stellate Cap Stage Dental papilla Neural crest cells Dentin & pulp Dental sac Periodontium Beginning of permanent teeth Bell Stage (Week 11–12) Cell differentiation Stellate Ameloblasts Enamel Odontoblasts Dentin Crown begins final shape Tooth Root Formation Epithelial root sheath Into mesenchyme Narrowing of pulp cavity into root canal Neurovascular passage Dental sac Cementoblasts Cement over dentin to neck of tooth Periodontal ligament