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DEVELOPMENT OF FACE/ Development of face, palate and jaw

• Introduction, General embryology○ Fertilization ○ Formation of germ layers ○ Development of face – •Pharyngeal arches, pouch & clefts ○ Development of nose. development of maxilla & mandible, development of eyes,development of lips & checks Development of head • Development of skull • Development of face.....

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DEVELOPMENT OF FACE/ Development of face, palate and jaw

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  2. 2. DEVELOPMENT OF FACE Dr. DISHIKA BHAGWANI PG 1 DEPARTMENT OF PEDODONTICS & PREVENTIVE DENTISTRY 2
  3. 3. CONTENT PART 1:- • Fertilization, cleavage • Formation of morula, blastocyst • Formation of germ layers • Formation of procordal plate , primitive streak & intraembryonic mesoderm • Formation of notochord • Sub-division of intraembryonic mesoderm • Embryonic folding • Stomodeum • Formation of pharyngeal arches, pouches & clefts • Derivatives of pharyngeal arches, pouches & clefts 3
  4. 4.  PART 2:- DEVELOPMENT OF -  MAXILLA  NOSE  LIP  CHEEK  PALATE  TONGUE  MANDIBLE  TOOTH  EYE  EAR  CONGENITAL ABNORMALITIES  REFERENCES 4
  5. 5. INTRODUCTION  The face and neck development of the human embryo refers to the development of the structures from the third to eighth week that give rise to the future head and neck.  This is due to germ layers:-  Etcoderm – outer layer  Mesoderm – middle layer  Endoderm – inner most layer 5
  6. 6. FERTILIZATION  Fertilization of the ovum occurs in the ampulla of the uterine tube.  The nucleus of the ovum- Female Pronucleus. The head of the spermatozoon -Male Pronucleus – zygote  The 23 chromosomes of both the pronuclei get mixed up- form 46 chromosomes. These undergo typical mitotic divisions to form an embryo having two cells (2nd Day) 6
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  8. 8. FORMATION OF MORULA & BLASTOCYST  Pre Implantation period -The period of one week from fertilization to implantation of fertilized egg  The fertilized ovum undergoes cleavage as it moves towards the uterine cavity  By 3rd day when zygote reaches uterus, it is a many celled mass called as MORULA which is 16 cell stage. 8
  9. 9.  On cross section, morula consists of inner cell mass surrounded by an outer cell layer.  Outer cell layer-later forms Trophoblast- provide nutrition to the growing embryo  Inner cell layer, is embryo proper- Embryoblast 9
  10. 10.  4th – 5th day, 32 – 64 cells  In the uterine cavity, some fluid passes into the morula thus separating the inner cell mass from trophoblast moving it to one side  Inner cell mass attaches to inner side of the trophoblast on one side only.  Hence, Morula Blastocyst  Cavity of the blastocyst is called as Blastocoel.  Blastocele seperates the cell into 2 parts – Trophoblast (outer cell layer) Embryoblast (inner cell mass) 10
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  12. 12. IMPLANTATION : 6TH DAY  Trophoblast attaches to the sticky endometrial surface on the posterior wall of the body of uterus  Surface of cells of trophoblast produces enzymes that digest the uterine endometrial cells which allows a deeper penetration of the cell mass 12
  13. 13. FORMATION OF GERM LAYERS 13
  14. 14.  Some cells of inner cell mass become flattened & come to line free surface- hypoblast/endoderm  Remaining, become columnar- epiblast/ectoderm  Bilaminar germ disc.  Space between epiblast and trophoblast- Amniotic Cavity filled with amniotic fluid.  Roof - amniogenic cells, floor - epiblast  Flattened cells from hypoblast spread inside blastocystic cavity, forming Heuser’s Membrane  Hence, the cavity now is lined by cells from all sides- Primary Yolk Sac 14
  15. 15.  The cells of trophoblast give rise to mass of cells- Extra Embryonic Mesoderm (Primary Mesoderm)- does not give rise to any tissues of the embryo.  Small cavities appear here and these ultimately join together to form a large cavity, the Extra Embryonic Coelom (Chorionic Cavity).  With the formation of extra embryonic coelom, the extra embryonic mesoderm is split – Parietal/somatopleuric extraembryonic mesoderm: Lines inside of trophoblast and outside of amniotic cavity Visceral/splanchnopleuric extraembryonic mesoderm: Lines outside the yolk sac 15
  16. 16. FORMATION OF PROCORDAL PLATE , PRIMITIVE STREAK & INTRAEMBRYONIC MESODERM  Day 13 – Prochordal plate – one circular end of disc – cubical cells of endoderm become columnar  Now, central axis is determined enabling us to distinguish the future head and tail ends.  Few columnar cells of epiblast at tail end begin to proliferate to form an elevation that bulges into the amniotic cavity- PRIMITIVE STREAK (day 15), appears on dorsal aspect of ectoderm of embryonic disc 16
  17. 17.  Cells that proliferate in primitive streak pass sideways between epiblast and hypoblast forming the Intra embryonic mesoderm (Secondary Mesoderm)- 16th day of IUL  By the end of third week, mesoderm migrates in lateral direction between ectoderm & endoderm, except at region of prochordal plate & area caudal to primitive streak, where ectoderm and endoderm remain in contact.  These regions remain thin & form buccopharyngeal membrane at prochordal plate & cloacal membrane caudal to primitive streak 17
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  19. 19. FORMATION OF NOTOCHORD  By day 16, a primitive knot of cells, the Henson’s node, appears at the cephalic end of the primitive streak  This knot gives rise to cells that forms the notochordal process 19
  20. 20. FORMATION OF NOTOCHORD  Between cranial end of Primitive streak & Caudal end of Prochordal plate  Cranial end of primitive streak thickens Primitive Knot/primitiv node/Henson’s node  Blastopore appears which is a depression in the knot  Cells in the primitive knot multiply, pass along the caudal end of prochordal plate, between endoderm and ectoderm forming solid cord known as Notochordal process/head process  Cells undergo rearrangement forming a solid rod called as NOTOCHORD 20
  21. 21. Notochordal process Notochord Neural Tube Brain Spinal cord 21
  22. 22. SUBDIVISION OF INTRAEMBRYONIC MESODERM  Paraxial Mesoderm  Lateral plate Mesoderm  Intermidate Mesoderm 22
  23. 23. Paraxial mesoderm Somitomeres (form bone in muscles in head region) Somites Sclerotome Dermatome Myotome Vertebral column Ribs Dermis Sub cutaneous tissue Striated muscle Occipital Somites- Muscle of tongue 23
  24. 24. LATERAL INTRAEMBRYONIC MESODERM  Spaces appear in this layer which later on join and form intraembryonic coelom.  At exterimities it join with etraembryonic coelom  Coronal section – lateral plate mesoderm closer with etcoderm is somatopleuric intraembryonic mesoderm  lateral plate mesoderm closer with endoderm is splanchopleuric intraembryonic mesoderm  Give rise to 3 cavities – pericardial cavity, pleural cavity & peritoneal cavity  Cephalic to coelom in lateral intraembryonic mesoderm – cavity does not pass from there i.e somatopleuric layer & splanchopleuric layer does not get separated – Septum Transversum – future diaphram 24
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  26. 26. EMBRYONIC FOLDING  With the embryonic disc becomes folded on itself at the head and tail ends.  The head fold is critical to the formation of the primitive stomatodaeum  Ectoderm comes through this fold to line the stomatodaeum  Stomatodaeum is separated from the gut by buccopharyngeal membrane. HEAD FOLD LATERAL FOLD TAIL FOLD 26
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  29. 29. EMBRYONIC DISC BEFORE HEAD AND TAIL FOLDS 29
  30. 30. AFTER FORMATION OF HEAD AND TAIL FOLDS 30
  31. 31. STOMODEUM  Stomodeum is a depression bounded cranially by a bulging produced by the brain & caudally by the bulging produced by pericardial cavity  An ectoderm lined depression  Seperated from the primitive pharynx by the buccopharyngeal (oropharyngeal) membrane  The membrane later breaks down & stomodeum open into pharynx  Forms the vestibule of oral cavity 31
  32. 32. FORMATION OF PHARYNGEAL POUCHES  Begin to develop at the 4th week of development  These are mesodermal thickening in the cranial most part of the foregut.  The mesoderm is arranged in six bars that run in the side wall of foregut.  Mesoderm of arches – paraxial & lateral plate mesoderm  Each of these bars fuse with the corresponding ones to form Pharyngeal arches.  A total of 6 arches are formed out of which 5 remain as the fifth arch soon degenerates. 32
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  34. 34. FORMATION OF PHARYNGEAL ARCHES 34
  35. 35. BRANCHIALARCHES (PHARYNGEALARCHES)  Paired structures  Develop from cephalic (head) portion of the neural crest  Appears as outpouching of mesoderm on both sides of developing pharynx (foregut)  Grow on either side of future head & neck of developing embryo & fuse at centre line  6 pairs  5th arch rudimentary 35
  36. 36.  In interval between 2 adjoining arches, the endoderm extends outward in the form of a pouch called endodermal/ pharyngeal pouches  This try to meet ectoderm – dips into this intervals as ectodemal cleft 36
  37. 37. Structures seen in Pharyngeal Arch • Skeletal element (Cartilage) • Striated Muscle • Nerve • Aortic arch 37
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  40. 40. DERIVATIVES OF FIRST PHARYNGEAL ARCH  2 portions  Dorsal - Maxillary process giving rise to premaxilla, maxilla, zygomatic bone & the part of temporal bone  Ventral – Mandibular process, which contains the MECKEL’s CARTILAGE During further development, Meckel’s cartilage disappears except for two small portions at its dorsal end that persist & form the incus & malleus 40
  41. 41. MECKEL’S CARTILAGE  Cartilage of first arch  Dorsal end – Incus & Malleus(of middle ear)  Ventral end – surrounded by developing mandible  Cartilage from middle ear to mandible disappears, but its  Sheath (perichondrium) forms:1)Anterior ligament of malleus 2)Sphenomandibular ligament  Mesenchyme – bones of face i.e maxilla, mandible, zygomatic bone, palatine bone, part of temporal bone 41
  42. 42. DERIVATIVES OF SECOND ARCH (HYOID ARCH) Cartilage of Second Arch (reichert’s cartilage) forms: Dorsal end of cartilage:- Stapes Styloid process Ventral part of cartilage:- Smaller (lesser) cornu of hyoid bone Superior part of body of hyoid bone  Part between dorsal and ventral parts disappears, but its Perichondrium(sheath):- Stylohyoid ligament 42
  43. 43. DERIVATIVES OF THIRD ARCH The cartilage of third arch forms: Ventral part of cartilage:- Greater cornu of hyoid bone Lower part of the body of hyoid bone  Dorsal part disappears 43
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  45. 45. DERIVATIVES OF FOURTH AND SIXTH ARCHES: The cartilages of Larynx are derived from fourth and sixth arches:- Thyroid cartilage Cricoid cartilage Corniculate cartilage Cuneiform cartilage Arytenoid cartilage Thyroid ligament 45
  46. 46. PHARYNGEAL POUCHES  Formed on endodermal side  Between pharyngeal arches  5 pairs  Last one of these is atypical & is considered as a part of 4th 46
  47. 47. Fifth pharyngeal pouch Last one to develop & is considered a part of 4th pouch Leads to development of Ultimobranchial body which in future leads to development of Thyroid gland Third pharyngeal pouch • Dorsal- proliferates to form Inferior parathyroid gland • Ventral- forms Thymus Fourth pharyngeal pouch Dorsal-Epithelium of this pouch forms the Superior parathyroid gland First pharyngeal pouch Dorsal-stalk like diverticulum Tubo tympanic recess 1)proximal part-Auditory tube 2)distal part-Middle ear cavity Ventral - Tongue Second pharyngeal pouch Dorsal- Tubo tympanic recess Ventral-The epithelial lining forms the primordium of the palatine tonsil 47
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  49. 49. PHARYNGEAL GROOVES(CLEFTS) • Form lateral ectodermal surface of neck region that separate arches • 5 week embryo;4 pharyngeal clefts of which only one contribute to the development of the definitive structure of embryo • Dorsal part -1st pharyngeal groove forms the External auditory meatus which is the only invagination on the side of the head • The 2nd, 3rd, 4th pharyngeal grooves merge together-the Cervical sinus which with further development disappears 49
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  54. 54. DEVELOPMENT OF FACE Dr. DISHIKA BHAGWANI PG 1 DEPARTMENT OF PEDODONTICS & PREVENTIVE DENTISTRY 54
  55. 55. CONTENT PART 1:- • Fertilization, cleavage • Formation of morula, blastocyst • Formation of germ layers • Formation of procordal plate , primitive streak & intraembryonic mesoderm • Formation of notochord • Sub-division of intraembryonic mesoderm • Embryonic folding • Stomodeum • Formation of pharyngeal arches, pouches & clefts • Derivatives of pharyngeal arches, pouches & clefts 55
  56. 56. PART 2:- • MAXILLA • MANDIBLE • PALATE • NOSE • LIP • CHEEK • TONGUE • TOOTH • EYE • EAR • CONGENITAL ABNORMALITIES • REFERENCES 56
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  58. 58. DEVELOPMENT OF FACE  Between 4-8 weeks I.U  Mandible is the first to form (4th week)  The facial proportions develop during the fetal period (9th week to birth)  During infancy & childhood, following development of teeth & paransal sinuses, facial skeleton increases in size & contribute to the definitive shape of face 58
  59. 59. DEVELOPMENT OF FACE  4th week, 2 prominent bulgings appear, separated by stomatodeum. (head bulge & pericardium bulge)  Each side of stomatodeum bounded by 1st arch  Mesenchyme covering developing forebrain proliferates & form downward projection called frontonasal process that overlaps upper part of stomatodeum  1st arch dorsal end gives rise to maxillary process (paired)  1st arch vental end give rise to mandibular process (paired) 59
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  61. 61.  Early in the 4th week  5 primordial swellings 1. One frontonasal process 2. Right & left maxillary process 3. Right & left mandibular process Prenatal growth of maxilla 61
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  63. 63. DEVELOPMENT OF NOSE 63
  64. 64. DEVELOPMENT OF NOSE  By the end of 4th week, bilateral oval shaped ectodermal thickenings called ‘Nasal Placodes’ appear on each side of the lower part of frontonasal prominence  Proliferation & migration of ectomesenchyme for formation of primitive nasal cavities  Nasal placodes are primordia of nose & nasal cavities 64
  65. 65.  At 28 days, localised thickenings develop within ectoderm of frontal process above to opening of stomodeum – Olfactory placodes/ nasal placodes  The placodes soon sink below the surface and continue with stomatodeum below. This is now called nasal pits. This are horse-shoe shaped swellings  Olfactory placodes  Nasal pits 65
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  67. 67. Edge of each pit is raised above the surface Horse shoe swelling  Lateral aspect – Lateral nasal process  Medial aspect - Medial nasal process Fronto Nasal process  Region of frontal prominence  Becomes narrower  Deeper part forms Nasal Septum  Mesoderm heaped up – prominence of nose 67
  68. 68.  The placodes now lie in the floor of the depression called ‘nasal pits’ • By the end of 6th week, nasal pits deepen & form nasal sacs • Nasal cavities - formed by extension of nasal pits • Each nasal sac grows dorsocaudally, ventral to the developing brain 68
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  71. 71.  Initially nasal sacs are separated from oral cavity by oronasal membrane  The oronasal membrane ruptures by 7th week, communicating the primitive nasal cavities with oral cavity  These communications are called primitive choncae & are located posterior to primary palate  After development of secondary palate, choncae change their position & become located at the junction of nasal cavity & the pharynx 71
  72. 72.  The superior, middle, inferior choncae develop on lateral wall of each nasal cavity  The ectodermal epithelium in the roof of each nasal cavity becomes specialized as the olfactory epithelium 72
  73. 73. DEVELOPMENT OF LIP 73
  74. 74. • Medial growth of maxillary process pushes median nasal process toward the midline & finally fuses with anatomic counterpart from opposite side. • The upper lip is formed from maxillary process of each side & the frontonasal process. DEVELOPMENT OF UPPER LIP 74
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  76. 76. • Mesoderm of lateral part of lip is - maxillary process. • Mesoderm of median part of lip is - frontonasal process • Overlying skin - ectoderm of same process • The mesenchyme from the 1st & 2nd pairs of pharyngeal arches invade the facial prominences & give rise to the muscles of mastication & muscles of facial expression respectively 76
  77. 77. DEVELOPMENT OF LOWER LIP  The mandibular process of two sides grow towards each other & fuse in midline 77
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  79. 79. DEVELOPMENT OF CHEEK • After formation of upper lip & lower lips the stomodeum becomes broader • Maxillary prominence continue to increase in size & laterally merge with mandibular prominences to form the CHEEK 79
  80. 80. INTER MAXILLARY SEGMENT  Gives rise to 1)Philtrum of lip 2)Premaxillary part of the maxilla, that bears the upper 4 incisors & the associated gums 3)Primary palate (region of hard palate just posterior to upper incisors) During 6th week the medial nasal process enlarge, grow medially & merge with each other in the midline to form the inter maxillary segment 80
  81. 81. DEVELOPMENT OF PALATE (PALATOGENESIS)  Begins at the end of 5th week  Gets completed by end of 12th week  Most critical period for development of palate is from end of 6th week to the beginning of 9th week Palate develops from – 1. 2 palatal process 2. Primitive palate 81
  82. 82. IMAGE 82
  83. 83. Definitive palate formed by fusion of Palatal process + posterior part of primitive palate 2 palatal process fuses Medial edges of palatal process + nasal septum 83
  84. 84.  Fusion with nasal septum begins anteriorly during 9th week, extends posteriorly & is completed by 12th week  Mesoderm in palate undergoes Intramembranous ossification  Only in anterior part - hard palate  Posterior part - soft palate  Frontonasal process - premaxilla 84
  85. 85. PALATE FORMATION • Maxillary components of 1st pharyngeal arch • Frontonasal process Primary palate • Hard palate • Soft palate Secondary palate 85
  86. 86. DEVELOPMENT OF TONGUE 86
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  89. 89. DEVELOPMENT OF TONGUE  4 weeks  Medial most part of 1st arch proliferates & form 2 lateral lingual swelling  One medial swelling – TUBERCULUM IMPAR  Behind Tuberculum impar -epithelium proliferates form a downgrowth from (thyroglossal duct) from which thyroid develops.  Foramen Caecum 89
  90. 90.  Hypobranchial eminence – midline swelling in medial ends of 2nd 3rd 4th arch.  Cranial part - Copula (2nd 3rd )  Caudal part (4th) - Epiglottis  Anterior 2/3rd by 2 lingual swellings and tuberculum impar  Porterior 1/3rd by cranial part of hypobranchial eminence 90
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  92. 92. POSTNATAL GROWTH OF MAXILLA Displacement Primary Secondary Growth at suture Frontonasal suture Fronto maxillary suture Zygomatic temporal suture Zygomatic maxillary suture Pterygopalatine suture Surface remodelling Orbital rim Maxillary tuberosity Lateral wall of nose Floor of nasal cavity Zygomatic bone Alveolar margins Maxillary tuberosity grows posterioly Maxilla moves forward 92
  93. 93. POSTNATAL GROWTH OF MAXILLA Displacement Primary Secondary Growth at suture Frontonasal suture Fronto maxillary suture Zygomatic temporal suture Zygomatic maxillary suture Pterygopalatine suture Surface remodelling Orbital rim Lateral wall of nose Floor of nasal cavity Palate Zygomatic bone Maxillary tuberosity 93
  94. 94. Prenatal growth of Mandible  4th week  MECKEL’s CARTILAGE 41st – 45th day  Major portion disappears  Remaining part develops into:- 1. Mental ossicles 2. Incus malleus 3. Spine of sphenoid 4. Anterior ligament of malleus 5. Spheno mandibular ligament 94
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  96. 96.  Single ossification centre for each half of mandible  Bifurcation of inferior alveolar nerve  At 7th week Intramembranous ossification  Rapid spread of ossification dorsally & ventrally forms body & ramus of mandible.  Ossification stops – later Lingula 96
  97. 97. Endochondral Bone Formation 10th -14th week, secondary accessory cartilages form 1. Condylar process 2. Coronoid process 3. Mental region 97
  98. 98. CONDYLAR PROCESS  Cone shape cartilage seen at 10th week  Starts osification at 14th week  Later migrates inferiorly to fuse with ramus by about 4 months  Most of cartilage is replaced by bone by middle of fetal life, but upper end persists into adulthood that acts as both growth as well as articular cartilage 98
  99. 99. CORONOID PROCESS  Cartilage seen in 10-14th week IU  Gets incorporated into expanding intramembranous bone of ramus and disappears before birth  Cartialge on either side of symphysis ossify in 7th month IU MENTALREGION 99
  100. 100. POSTNATAL GROWTH OF MANDIBLE Bone deposition & resorption 1. Ramus 2. Body of mandible 3. Chin 4. Lingual tuberosity 5. Angle of mandible 6. Alveolar process 7. Condyle 8. Coronoid process 100
  101. 101. Angle of mandible Mental foramen Alveolar ridge 101
  102. 102. DEVELOPMENT OF EYE 102
  103. 103. Optic vesicle • Neural plate • Optic sulcus • Optic vesicle • Optic stalk Lens vesicle • Surface ectoderm • Lens placode • Lens vesicle Optic cup • Optic vesicle • Optic cup DEVELOPMENT OF EYE 103
  104. 104. Optic vesicle • Neural plate • Optic sulcus • Optic vesicle • Optic stalk Lens vesicle • Surface ectoderm • Lens placode • Lens vesicle Optic cup • Optic vesicle • Optic cup DEVELOPMENT OF EYE 104
  105. 105.  5th week 3 sources: 1. Neuro ectoderm of forebrain – retina, optic nerve 2. Surface ectoderm of head – lens 3. Mesoderm between these layers – eye muscle & vascular tissues First appearance of eye – Lens placode Lens placode Sinks below surface Eyeball produces buldging105
  106. 106. DEVELOPMENT OF EAR 106
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  108. 108. EXTERNAL EAR External acoustic meatus:- Develops by deepening of dorsal end of 1st pharyngeal cleft Pinna or Auricle:- Six mesenchymal hillocks- Auricular hillocks develop from 1st & 2nd pharyngeal arch Tympanic membrane - eardrum DEVELOPMENT OF EAR 108
  109. 109. MIDDLE EAR Develops from tubo tympanic recess derived from 1st pharyngeal pouch Ossicles – Malleus Incus Stapes Eustachian tube – middle ear to back of nose INTERNAL EAR Otic placode 1. Cochlea 2. Vestibule 3. Semicircular canal 109
  110. 110. PARANASAL SINUSES  During late fetal life the remainder develops after birth  They form as outgrowths or diverticula of walls of nasal cavities & become air filled extensions of nasal cavities in the adjacent bone 1. Frontal 3-4 months I.U 2. Ethmoidal 4 months I.U 3. Maxillary Develops at 10 weeks of I.U 4. Sphenoidal 4 months of I.U 110
  111. 111. DERIVATIVES OF FACIAL COMPONENTS FRONTONASAL PROMINENCE forms- 1. Forehead & the bridge of nose 2. Frontal & nasal bones MAXILLARY PROMINENCES forms- 1.Upper cheek regions & most of the upper lip 2.Maxilla, zygomatic bone, secondary palate111
  112. 112. Mandibular prominence fuses- 1. Chin, lower lip, & lower cheek regions 2. Mandible Lateral nasal prominence forms- Alae of nose Medial nasal prominences form- Intermaxillary segment112
  113. 113. MUSCULAR DEVELOPMENT  During 5th week, myoblast proliferate within the mandibular arch  By the 7th week, cells migrate & differentiate into 4 MOM 1. Lateral pterygoid 2. Medial pterygoid 3. Masseter 4. Temporalis  The muscle cells within the hyoid arch & in the occipital myotomes undergo proliferation & migrate anteriorly toward the floor of the mouth to form muscles of the tongue Muscle cells of the 3rd & 4th arch form the pharyngeal muscles 1. Stylopharyngeus 2. Cricothyroid 3. Levator palatini 4. Constrictor muscle of pharynx 113
  114. 114. CONGENITALANOMALIES Craniofacial Defects Crouzan syndrome Treacher Collin syndromeRobin sequenceDi George anomaly Hemifacial Microsomia 114
  115. 115. Developmental defects of TONGUE Microglossia Macroglossia Ankyloglosia Fissured tongue Median rhomboid glossitis Benign migratory glossitis Bifid tongue 115
  116. 116. Abnormalities in LIP & PALATE Cleft lip – Unilateral Bilateral Cleft palate 116
  117. 117. Developmental defects of JAW • Micrognathia • Agnathia • Macrognathia • Facial hemihypertrophy • Facial hemiatrophy Developmental defects of NOSE • Bifid nose • Proboscis 117
  118. 118. Defects in development of EAR Preauricular pits & appendages Malleus/incus fixation Absence of long process of incus Congenital fixation of stapes Failure of annular ligament development Congenital preauricular sinus 118
  119. 119. Defects in development of EYE  Cyclopia  Absence of eye i.e anopthalmia  Colobomas of eyelids  Congenital ptosis  Fusion of eyelids – cryptophtalmos  Epicanthal fold  Corneal dermoids  Congenital glaucoma  Fraser’s syndrome  Stromal dystrophy 119
  120. 120. REFERENCES  Orbans, textbook of hiostology  I B Singh, textbook of embryology  Balaji, textbook of orthodontics 120
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