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Branchial pharyngeal arches_concise

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Branchial pharyngeal arches_concise

  1. 1. Head and Neck Embryology R. Dale Reynolds University of Texas at Houston Plastic and Reconstructive Surgery
  2. 2. Branchial and Pharyngeal Arches <ul><li>Fourth week </li></ul><ul><li>Neural crest cells </li></ul><ul><ul><li>Most skeletal and connective tissue in H&N </li></ul></ul><ul><li>Numbered cranial  caudal </li></ul><ul><li>Four well-defined pairs visible externally </li></ul><ul><li>Fifth and sixth rudimentary </li></ul><ul><li>Separated by grooves </li></ul>
  3. 3. Branchial and Pharyngeal Arches <ul><li>First = Mandibular </li></ul><ul><ul><li>Mandibular Prominence  jaw </li></ul></ul><ul><ul><li>Maxillary Prominence  maxilla/zyg/temp </li></ul></ul><ul><li>Second = Hyoid </li></ul>
  4. 5. Branchial and Pharyngeal Arches <ul><li>Fate </li></ul><ul><ul><li>Typical arch contains </li></ul></ul><ul><ul><ul><li>Aortic arch </li></ul></ul></ul><ul><ul><ul><li>Cartilaginous rod (skeleton of arch) </li></ul></ul></ul><ul><ul><ul><li>Muscular component </li></ul></ul></ul><ul><ul><ul><li>Nerve </li></ul></ul></ul>
  5. 6. Branchial and Pharyngeal Arches
  6. 7. Pharyngeal Pouches <ul><li>First </li></ul><ul><ul><li>Tubotympanic recess  tympanic membrane </li></ul></ul><ul><ul><li>Connects with pharynx  eustachian tube </li></ul></ul><ul><li>Second </li></ul><ul><ul><li>Palatine tonsil, tonsillar fossa </li></ul></ul><ul><li>Third </li></ul><ul><ul><li>Inferior parathyroid gland </li></ul></ul><ul><ul><li>Thymus </li></ul></ul>
  7. 8. Pharyngeal Pouches <ul><li>Fourth </li></ul><ul><ul><li>Superior parathyroid gland </li></ul></ul><ul><ul><li>Ultimobranchial body fuses with thyroid </li></ul></ul><ul><ul><li>Parafollicular C cells  calcitonin </li></ul></ul><ul><li>Fifth </li></ul><ul><ul><li>Rudimentary </li></ul></ul>
  8. 10. Pharyngeal Pouches
  9. 11. Branchial or Pharyngeal Grooves <ul><li>Four on each side </li></ul><ul><li>Separate branchial or pharyngeal arches </li></ul><ul><li>First  External acoustic meatus </li></ul><ul><li>Others lie in depression (cervical sinus) which obliterates </li></ul>
  10. 12. Branchial or Pharyngeal Grooves
  11. 13. Branchial or Pharyngeal Membranes <ul><li>Only one pair contribute to adult structures </li></ul><ul><li>First  tympanic membrane </li></ul>
  12. 14. Branchial and Pharyngeal Anomalies <ul><li>Congenital Auricular Sinuses and Cysts </li></ul><ul><ul><li>Small sinuses (pits) and cysts commonly found in a triangular area of skin anterior to the ear </li></ul></ul><ul><ul><li>May be remnant of branchial or pharyngeal groove </li></ul></ul>
  13. 15. Branchial and Pharyngeal Anomalies <ul><li>Branchial Sinuses </li></ul><ul><ul><li>Lateral cervical: Uncommon, open externally (neck), failure of second groove or cervical sinus to obliterate </li></ul></ul><ul><ul><li>External branchial sinuses: Mucous d/c from infant’s neck, bilateral in 10% </li></ul></ul><ul><ul><li>Internal branchial sinuses: Rare, persistent second pouch, open into intratonsillar cleft </li></ul></ul>
  14. 16. Branchial and Pharyngeal Anomalies <ul><li>Branchial Fistula </li></ul><ul><ul><li>Connection between intratonsillar cleft and neck </li></ul></ul><ul><ul><li>Runs between internal and external carotids </li></ul></ul><ul><ul><li>Persistent second groove and second pouch </li></ul></ul>
  15. 17. Branchial and Pharyngeal Anomalies <ul><li>Branchial Cysts </li></ul><ul><ul><li>Develop along anterior border of sternocleidomastoid </li></ul></ul><ul><ul><li>Most inferior to angle of mandible </li></ul></ul><ul><ul><li>Often present in adulthood </li></ul></ul><ul><ul><li>Remnants of cervical sinus and/or second groove </li></ul></ul>
  16. 18. Branchial and Pharyngeal Anomalies <ul><li>Branchial Vestiges </li></ul><ul><ul><li>Cartilaginous or bony remnants </li></ul></ul><ul><ul><li>Usually anterior to inferior third of sternocleidomastoid </li></ul></ul>
  17. 19. Branchial and Pharyngeal Anomalies <ul><li>First Arch Syndrome </li></ul><ul><li>First branchial or pharyngeal arch </li></ul><ul><ul><li>Treacher Collins syndrome </li></ul></ul><ul><ul><ul><li>Malar hypoplasia, down-slanting of palpebral fissures, lower eyelid colobomas, ear deformations </li></ul></ul></ul><ul><ul><li>Pierre Robin syndrome </li></ul></ul><ul><ul><ul><li>Hypoplasia of the mandible, cleft palate, and defects of the eye and ear </li></ul></ul></ul>
  18. 20. Branchial and Pharyngeal Anomalies <ul><li>DiGeorge Syndrome (Congenital Thymic and Parathyroid Aplasia) </li></ul><ul><ul><li>Failure of third and fourth pouches to differentiate into thymus and parathyroid glands </li></ul></ul><ul><ul><li>Hypoparathyroidism </li></ul></ul><ul><ul><li>Increased incidence of infections </li></ul></ul><ul><ul><li>Shortened philtrum </li></ul></ul><ul><ul><li>Low-set notched ears </li></ul></ul><ul><ul><li>Nasal clefts </li></ul></ul><ul><ul><li>Thyroid hypoplasia </li></ul></ul><ul><ul><li>Cardiac anomalies </li></ul></ul>
  19. 21. Branchial and Pharyngeal Anomalies <ul><li>Accessory Thymic Tissue </li></ul><ul><ul><li>Isolated portion of thymic tissue may persist </li></ul></ul><ul><ul><li>Often in close association with inferior parathyroid gland </li></ul></ul>
  20. 22. Branchial and Pharyngeal Anomalies <ul><li>Ectopic Parathyroid Gland </li></ul><ul><ul><li>Variable in number (2-6) and location </li></ul></ul><ul><ul><li>Superior more constant than inferior </li></ul></ul><ul><ul><li>Thyroid to thorax </li></ul></ul><ul><li>Absence of Parathroid Gland </li></ul>
  21. 23. Thyroid Gland <ul><li>Begins as thickening in the floor of the pharynx </li></ul><ul><li>Forms an outpouching (thyroid diverticulum) </li></ul><ul><li>Descends into neck passing ventral to hyoid bone and laryngeal cartilages </li></ul><ul><li>Connected to tongue by thryoglossal duct at foramen cecum </li></ul>
  22. 24. Thyroid Gland <ul><li>Isthmus connects right and left lobes </li></ul><ul><li>Thyroglossal duct degenerates </li></ul><ul><li>Blind pit marks the foramen cecum </li></ul><ul><li>Pyramidal lobe extends superiorly from the isthmus in fifty per cent </li></ul>
  23. 25. Thyroid Anomalies <ul><li>Thyroglossal Duct Cysts and Sinuses </li></ul><ul><ul><li>May form anywhere along the course followed by the thyroglossal duct </li></ul></ul><ul><ul><li>Most seen by 5 yo </li></ul></ul><ul><ul><li>Asymptomatic unless infected </li></ul></ul><ul><ul><li>Midline, painless, moveable neck mass </li></ul></ul><ul><ul><li>Sinuses are open, cysts are closed </li></ul></ul>
  24. 26. Thyroid Anomalies <ul><li>Ectopic Thyroid Gland </li></ul><ul><ul><li>Lingual thyroid </li></ul></ul><ul><ul><ul><li>Result of failure to descend </li></ul></ul></ul><ul><ul><ul><li>Often only thyroid tissue present </li></ul></ul></ul><ul><ul><li>Accessory thyroid tissue </li></ul></ul><ul><ul><ul><li>Tongue </li></ul></ul></ul><ul><ul><ul><li>Neck, superior or lateral to thyroid </li></ul></ul></ul>
  25. 27. Tongue <ul><li>General </li></ul><ul><ul><li>Merged distal tongue buds  anterior 2/3 </li></ul></ul><ul><ul><li>Copula and hypobranchial eminence  posterior 1/3 </li></ul></ul><ul><ul><li>Terminal sulcus divides anterior and posterior </li></ul></ul><ul><li>Taste buds </li></ul><ul><ul><li>Most are filiform papillae and are sensitive to touch </li></ul></ul><ul><li>Muscles </li></ul><ul><ul><li>Supplied by XII except for palatoglossus (X) </li></ul></ul>
  26. 28. Tongue <ul><li>Nerves </li></ul><ul><ul><li>Sensory for anterior 2/3 is from V 3 (lingual) </li></ul></ul><ul><ul><li>Chorda tympani (VII) taste buds for anterior 2/3 (except for vallate papillae supplied by IX) </li></ul></ul><ul><ul><li>IX supplies posterior 1/3 </li></ul></ul><ul><ul><li>X (Superior Laryngeal) supplies area around epiglottis </li></ul></ul>
  27. 29. Tongue <ul><li>Taste buds </li></ul><ul><ul><li>Most are filiform papillae and are sensitive to touch </li></ul></ul>
  28. 30. Tongue Anomalies <ul><li>Lingual cysts and Fistulas </li></ul><ul><ul><li>Persistence of thyroglossal duct open to foramen cecum </li></ul></ul><ul><li>Ankyloglosia (Tongue-Tie) </li></ul><ul><ul><li>Short frenulum to tip, stretches with time </li></ul></ul><ul><li>Macroglossia </li></ul><ul><ul><li>Usually from muscular hypertrophy or lymphangioma </li></ul></ul><ul><li>Microglossia </li></ul><ul><ul><li>Associate with micrognathia and limb defects (Hanhart’s syndrome) </li></ul></ul><ul><li>Bifid or Cleft Tongue (Glossochisis) </li></ul><ul><ul><li>Incomplete fusion of distal tongue buds  deep median sulcus </li></ul></ul>
  29. 31. Ear <ul><li>Three anterior hillocks of the first branchial arch form the tragus, helical crus, and superior helix </li></ul><ul><li>Three posterior hillocks of the second branchial arch form the antihelix, antitragus, and lobule </li></ul><ul><li>First branchial groove forms external auditory meatus </li></ul><ul><li>Microtia </li></ul><ul><ul><li>1:6000-8000 births </li></ul></ul><ul><ul><li>Associated with hemifacial microsomia </li></ul></ul><ul><li>Nerves </li></ul><ul><ul><li>Great auricular (C2, C3)  lower lateral/lower cranial </li></ul></ul><ul><ul><li>Auriculotemporal (V 3 )  superolateral/ anterior and superior external auditory canal </li></ul></ul><ul><ul><li>Lesser occipital  superior cranial </li></ul></ul><ul><ul><li>Arnold’s (X)  concha / posterior auditory canal (referred oropharyngeal pain) </li></ul></ul>
  30. 32. Ear
  31. 33. Face <ul><li>Stomodeum is primitive mouth </li></ul><ul><li>Five facial primordia appear as prominences around stomodeum </li></ul><ul><ul><li>Single fronto(  forehead)nasal{  most of nose(except septum/alae)} prominence  optic vesicles  eyes </li></ul></ul><ul><ul><li>Paired maxillary prominences  lateral upper lip, most of maxilla, secondary palate </li></ul></ul><ul><ul><li>Paired mandibular prominences  chin, lower lip, lower cheek </li></ul></ul>
  32. 34. Face <ul><li>Mandible forms first </li></ul><ul><li>Nasal placodes  nasal pits </li></ul><ul><li>Six auricular hillocks  ear </li></ul><ul><li>Epithelial cord canalizes in nasolacrimal groove  nasolacrimal duct </li></ul><ul><ul><li>Atresia if canalization fails </li></ul></ul>
  33. 35. Face <ul><li>Lateral nasal prominence  nasal alae </li></ul><ul><li>Medial nasal prominences merge  intermaxillary segment  philtrum of lip, premaxilla (gum), primary palate, nasal septum </li></ul><ul><li>Second arch  muscles of facial expression (VII) </li></ul><ul><li>First arch  muscles of mastication (V) </li></ul>
  34. 36. Face <ul><li>Labiogingival lamina  lips and gingivae, lingual frenulum </li></ul><ul><li>Changes </li></ul><ul><ul><li>Early fetal period: Flat nose and underdeveloped mandible </li></ul></ul><ul><ul><li>Enlarging brain: Prominent forehead, medial movement of eyes and external ears rise </li></ul></ul>
  35. 37. Nasal Cavities <ul><li>Nasal placodes  nasal pits  deepening  nasal sacs </li></ul><ul><li>Oronasal membrane separates the oral cavity from the nasal sacs </li></ul><ul><li>Membrane ruptures  primitive chonae (opening b/w nasal cavity and nasopharynx) </li></ul>
  36. 38. Nasal Cavities <ul><li>Olfactory system </li></ul><ul><ul><li>Ectodermal epithelium in the roof of each nasal cavity  specialized  olfactory epithelium </li></ul></ul><ul><ul><li>Some epithelial cells  olfactory receptors (axons become olfactory nerve) and grow into bulbs of the brain </li></ul></ul>
  37. 39. Nasal Cavities <ul><li>Paranasal sinuses </li></ul><ul><ul><li>From outgrowths of nasal cavity walls  pneumatic (air-filled) extensions of the nasal cavities in adjacent bones </li></ul></ul><ul><ul><li>Original openings of the outgrowths persist as the orifices of the adult sinuses </li></ul></ul><ul><ul><li>Most are rudimentary in newborns </li></ul></ul><ul><ul><ul><li>Frontal sinuses are visible by seven </li></ul></ul></ul><ul><ul><ul><li>Sphenoidal sinuses usually evident by two </li></ul></ul></ul><ul><ul><li>Vomeronasal cartilage  narrow cartilage strips between the inferior edge of the cartilage of nasal septum and vomer </li></ul></ul>
  38. 40. Palate <ul><li>Palatogenesis from 5 th – 12 th week </li></ul><ul><li>Primary Palate </li></ul><ul><ul><li>Median palatine process begins to develop from deep intermaxillary segment of maxilla </li></ul></ul><ul><ul><li>Primary palate forms the premaxillary part of the maxilla </li></ul></ul><ul><ul><li>Represents a small part of the adult hard palate (anterior to the incisive foramen that lodges the incisor teeth) </li></ul></ul>
  39. 41. Palate <ul><li>Secondary Palate </li></ul><ul><ul><li>Primordium of hard and soft palates that extend posteriorly from the incisive foramen </li></ul></ul><ul><ul><li>Shelf-like structures called lateral palatine processes (palatine shelves) project inferiomedially on each side of the tongue </li></ul></ul>
  40. 42. Palate <ul><li>Secondary Palate </li></ul><ul><ul><li>Shelves elongate and ascend to a horizontal position superior to the tongue </li></ul></ul><ul><ul><li>Shelves fuse in a median plane with nasal septum and posterior primary palate </li></ul></ul><ul><ul><li>Elevation to the horizontal position is thought to be caused by the intrinsic shelf elevating force by hydration of hyaluronic acid in the shelves </li></ul></ul>
  41. 43. Palate <ul><li>Secondary Palate </li></ul><ul><ul><li>Nasal septum develops from downgrowths of merged medial nasal prominences </li></ul></ul><ul><ul><li>Fusion between nasal septum and palatine processes proceeds anteriorly to posteriorly </li></ul></ul>
  42. 44. Palate <ul><li>Secondary Palate </li></ul><ul><ul><li>Bone develops in primary palate forming the premaxillary part of the maxilla which lodges between the incisor teeth </li></ul></ul><ul><ul><li>Bone extends from the maxillae and palatine bones in to the lateral palatine processes to form the hard palate </li></ul></ul>
  43. 45. Palate <ul><li>Secondary Palate </li></ul><ul><ul><li>Posterior aspects do not ossify </li></ul></ul><ul><ul><li>Extend posteriorly beyond nasal septum and fuse to form the soft palate and uvula </li></ul></ul><ul><ul><li>Palatine raphe permanently indicates the line of fusion of the lateral palatine processes </li></ul></ul>
  44. 46. Palate <ul><li>Secondary Palate </li></ul><ul><ul><li>Small nasopalatine canal persists between premaxilla and palatine processes as incisive foramen (openings for incisive canals) </li></ul></ul>
  45. 47. Clefts <ul><ul><li>Lip and palate </li></ul></ul><ul><ul><ul><li>Upper lip and anterior maxilla with or without hard and soft palate </li></ul></ul></ul><ul><ul><ul><li>Hard and soft palate </li></ul></ul></ul><ul><ul><li>Complete posterior (to incisive foramen) palate </li></ul></ul><ul><ul><li>Anterior cleft anomalies </li></ul></ul><ul><ul><ul><li>Cleft lip, with or without a cleft of the alveolar part of the maxilla </li></ul></ul></ul><ul><ul><ul><li>Result from deficiency of mesenchyme in the maxillary prominences and intermaxillary segment </li></ul></ul></ul>
  46. 48. Clefts <ul><li>Posterior cleft anomalies </li></ul><ul><ul><li>Clefts of secondary or posterior palate that extend through the soft and hard palate to the incisive foramen </li></ul></ul><ul><ul><li>Caused by defective development of the secondary palate and result from the growth distortions of the lateral palatine processes (shelves) which prevent their medial migration and fusion </li></ul></ul>
  47. 49. Clefts <ul><ul><li>Lip </li></ul></ul><ul><ul><ul><li>1:1000 births, 70% male, </li></ul></ul></ul><ul><ul><ul><li>Caucasion>Asian>Hispanic>AA </li></ul></ul></ul><ul><ul><ul><li>Notches on vermilion border to alveolar maxilla </li></ul></ul></ul>
  48. 50. Clefts <ul><ul><li>Unilateral </li></ul></ul><ul><ul><ul><li>Failure of maxillary prominence on affected side to unite with merged medial nasal prominences </li></ul></ul></ul><ul><ul><ul><li>Consequence of failure of mesenchymal masses to merge and the mesenchyme to proliferate and smooth out the overlying epithelium </li></ul></ul></ul><ul><ul><ul><li>Results in persistent labial groove </li></ul></ul></ul><ul><ul><ul><li>Epithelium in the labial groove stretches and tissues of the floor breakdown </li></ul></ul></ul><ul><ul><ul><li>Lip is divided into medial and lateral parts </li></ul></ul></ul><ul><ul><ul><li>Bridge of tissue (Simonart’s band) joins parts of incomplete cleft lip </li></ul></ul></ul>
  49. 51. Unilateral cleft lip
  50. 52. Clefts <ul><ul><li>Bilateral </li></ul></ul><ul><ul><ul><li>Failure of mesenchymal masses in the maxillary prominences to met and unite with the merged medial nasal prominences </li></ul></ul></ul><ul><ul><ul><li>Epithelium in both labial grooves becomes stretched and breaks down </li></ul></ul></ul><ul><ul><ul><li>May have varying degrees of defects on each side </li></ul></ul></ul><ul><ul><ul><li>When there is a complete bilateral cleft of the lip and alveolar part of the maxilla, the intermaxillary segment hangs free and projects anteriorly </li></ul></ul></ul><ul><ul><ul><li>These defects are deforming because of loss of continuity with the orbicularis oris muscle which purses the lips </li></ul></ul></ul>
  51. 53. Clefts <ul><ul><li>Median (rare) </li></ul></ul><ul><ul><ul><li>Upper </li></ul></ul></ul><ul><ul><ul><ul><li>Mesenchymal deficiency causing partial or complete failure of medial nasal prominences to merge and form the intermaxillary segment </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Characteristic of the Mohr syndrome </li></ul></ul></ul></ul><ul><ul><ul><li>Lower </li></ul></ul></ul><ul><ul><ul><ul><li>Failure of mesenchymal masses in the mandibular prominences to merge completely and smooth out the embryonic cleft between them </li></ul></ul></ul></ul>
  52. 54. Clefts <ul><ul><li>Palate </li></ul></ul><ul><ul><ul><li>+/- lip in 1:2500 births, females </li></ul></ul></ul><ul><ul><ul><li>Uvula, soft/hard palate, lip, alveolar maxilla </li></ul></ul></ul><ul><ul><ul><li>Failure of mesenchymal masses in lateral palatine processes (shelves) to fuse with each other, the nasal septum and posterior margin of the median palatine process </li></ul></ul></ul>
  53. 55. Clefts <ul><ul><li>Palate (divided by incisive foramen) </li></ul></ul><ul><ul><ul><li>Anterior </li></ul></ul></ul><ul><ul><ul><ul><li>Failure of mesenchymal masses in lateral palatine masses to fuse with primary palate </li></ul></ul></ul></ul><ul><ul><ul><li>Posterior </li></ul></ul></ul><ul><ul><ul><ul><li>Failure of mesenchymal masses in lateral palatine masses to fuse with nasal septum </li></ul></ul></ul></ul><ul><ul><ul><li>Both </li></ul></ul></ul><ul><ul><ul><ul><li>Failure of mesenchymal masses in lateral palatine masses to fuse with each other, primary palate or nasal septum </li></ul></ul></ul></ul>
  54. 56. Craniofacial clefts <ul><li>1.4-5.1:100,000 </li></ul><ul><li>Numbered 0-14 (sum=14) </li></ul><ul><ul><li>0-7 are facial </li></ul></ul><ul><ul><li>8-14 are cranial </li></ul></ul><ul><li>Number 7 is least rare (1:5600) =hemifacial microsomia (hypoplasia of mandibular ramus, hypoplasia of midface, others) associated with Goldenhar syndrome </li></ul><ul><li>Bilateral 6,7,8 is complete form of Treacher-Collins </li></ul>
  55. 57. Others <ul><li>Facial clefts </li></ul><ul><li>Macrostomia </li></ul><ul><li>Microstomia </li></ul><ul><li>Nasal </li></ul><ul><li>Single nostril </li></ul><ul><li>Bifid nose </li></ul><ul><li>Absence </li></ul>
  56. 66. END

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