1. Head and Neck Development: Skull & Face Audrone Biknevicius 2005-CPC2

2. CRANIOFACIAL ANOMALIES One-third of all congenital defects Etiology: Multifactorial inheritance Teratogens: alcohol, retinoic acid, toluene, smoking, radiation, hyperthermia Genetics

3. 4 Week Embryo – Sagittal Section From Carlson, l999 Primordial tissues Stomodeum Frontonasal prominence

4. 4 Week Embryo - Lateral View From Carlson, l999

5. 4-8 Week Embryo – Frontal View From Carlson, 1999

6. Pharyngeal Arches Cranial nerve Aortic arch (from mesoderm) Muscle component (from mesoderm) Cartilaginous rod (from neural crest cells)

7. Skull Neurocranium (brain case) Viscerocranium (face)

8. Intramembranous ossification Endochondral ossification Development of Skull

9. PRIMARY DETERMINANT OF GROWTH & DEVELOPMENT MembranousCartilagenous Neurocraniumintracranial pressure genetics Viscerocraniumadjacent soft tissues genetics (tongue, eye)

10. Neurocranium Primarily derived from neural crest cells Cartilaginous neurocranium (chondrocranium) – skull base Membranous neurocranium – cranial vault

11. Cartilaginous Neurocranium – Skull Base Sphenooccipital synchondrosis site of AP cranial base growth until ~ 20 yo From Larsen, 1997

12. Achondroplasia Premature closure of primary growth plates Sphenooccipital synchondrosis - AP short cranial base, moon-shaped profile Autosomal dominant; most common form of dwarfism (1/26,000 live births) www.jrn.columbia.edu/cns/ 2002-02-22/syndication/

13. www.bio.psu.edu/faculty/strauss/ anatomy/skel/fetal.htm Cartilaginous Neurocranium – Stylomastoid Foramen Undeveloped mastoid process Ring-shaped external auditory meatus Superficial position of stylomastoid foramen

14. Forceps-Assisted Delivery www.millermedart.com/ pages/s_ob5.html To protect facial nerve: Avoid placing forceps immediately behind ear

15. From Larsen, 1997 Membranous Neurocranium – Skull Vault Flat bones of the skull Sutures and fontanelles

16. Gardner, Gray & O’Rahilly Anatomy Childbirth – yielding without cracking Growth - expansion of cranial vault with growth of brain Sutures and Fontanelles

17. www.bio.psu.edu/faculty/strauss/ anatomy/skel/fetal.htm Anterior Fontanelle Palpable during 1 st year If small – premature fusion If bulged – increased intracranial pressure If depressed – dehydration Venipuncture

18. Hydrocephaly

19. From Carlson, 1999 From Larsen, 1997 Craniosynostosis (premature fusion) ScaphocephalyAcrocephalyCrouzon syndrome Sagittal suture Most common (>50%) Coronal suture Aperts syndrome >2 sutures (coronal, sagittal) Face, teeth, ear

20. Viscerocranium Primarily derived from neural crest cells Membranous viscerocranium – face (below orbits) – derived from PA 1 (forehead = membranous neurocranium) Cartilaginous viscerocranium – middle ear bones, hyoid bone, laryngeal cart.

21. Face Formation 4-8 Week Embryo – Frontal View From Carlson, 1999

22. Development of Face BONE EMBRYOLOGY FACE Forehead Cheek, upper jaw, lateral upper lip Philtrum, medial upper lip Lower jaw, lower lip, chin Frontal Maxilla Premaxilla Mandible Frontonasal prominence Maxillary process Intermax. seg. Mandibular prominence

23. From Carlson, 1999 Initial sites of development: Optic vesicles - laterally Auditory vesicles – inferiorly Nasal pits – frontal but widely separated Eyes, Ears and Nose

24. Frontonasal Prominence Defect: Excessive Tissue - Frontonasal dysplasia From Carlson, 1999 Broad nasal bridge & hypertelorism Can be associated with other defects (e.g., tetralogy of Fallot)

25. Defects of the Frontonasal Prominence: Deficient Tissue - Holoprosencephaly Defective formation of prosencephalon (forebrain) Common olfactory abnormalities Most severe – cylcopia (fusion of op[tic primordia) Etiology: week 3 alcohol consumption, autosomal recessive, excessive retinoic acid, multifactorial From Larsen, 1997

26. Palate Formation From Carlson, 1999

27. Development of Palate Primary Intermaxillary palate segment Hard Palate Maxilla Palatine Lateral palatine processes/ shelves Soft Palate BONE* EMBRYOLOGY PALATE *Primary palate: premaxillary part of maxilla (houses incisors) Secondary palate: maxilla and palatine

28. Palate & Nasal Septum Formation From Carlson, 1999

29. Face Formation, Facial Clefting From Carlson, 1999

30. Distinct malformations Both are multifactorial, genetic, teratogens Cleft Lip Hypoplasia of maxillary process Failure of fusion of maxillary and nasomedial processes Most common congential malformation of H&N Cleft Palate Failure of fusion of palatal shelves or palatal shelf with primary palate Cleft Lip and Cleft Palate

31. Cleft Palate

32. Cleft lip repair www.nypchildren.org/about/ craniofacial.html

33. Why are babies so cute? Somatic tissues Neural tissues AGE SIZE Adult size GROWTH PATTERNS ~2 yo ~16 yo

34. www.liv.ac.uk/HumanAnatomy/ phd/mbchb/stroke/stk1.html Development of Paranasal Sinuses Form as invaginations of nasal epithelium into diploe of cranial bone

35. www.bio.psu.edu/faculty/strauss/ anatomy/skel/fetal.htm Paranasal sinuses Maxillary & ethmoid sinuses begun to develop in the fetus but are small at birth Sphenoid & frontal sinuses develop postnatally

36. www.iadmfr.org/oradlistimages/ image.htm Dental Development Permanent teeth dental formula I,C,P,M/I,C,P,M 2,1,2,3/2,1,2,3 (panoramic radiograph ) Deciduous (milk) teeth dental formula I,C,M/I,C,M 2,1,2/2,1,2 (lateral radiograph ) sumerdoc.blogspot.com