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Axial Skeleton - Skull

Axial Skeleton - Skull. Neurocranium Dermatocranium Splanchnocranium. Dermatocranium. Phylogeny – membrane bone which evolved from dermal armor Roofing bones Along side and above brain. Roofing Bones. Nasal Frontal Parietal Orbital Lacrimal Jugal = Infraorbital = Zygomatic Squamosal.

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Axial Skeleton - Skull

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  1. Axial Skeleton - Skull • Neurocranium • Dermatocranium • Splanchnocranium

  2. Dermatocranium • Phylogeny – membrane bone which evolved from dermal armor • Roofing bones • Along side and above brain

  3. Roofing Bones • Nasal • Frontal • Parietal • Orbital • Lacrimal • Jugal = Infraorbital = Zygomatic • Squamosal

  4. Look at the Skull & Lower Jaw components page. Examine the roofing bones.

  5. Upper jaw • Premaxilla • Maxilla

  6. Lower Jaw • Dentary - largest • Splenial – small, dorsomedial • Surangular - lateral • Angular – medial, becomes typanic bulla • Coronoid – medial • Prearticular – medial & caudal – becomes anterior malleus in mammals

  7. Key Points • Look at upper and lower jaw dermatocranium bones on Skull & Lower Jaw Components page • Give an example of homology. • What trend do you see in lower jaw evolution?

  8. Primary Palate Bones • Roof of oropharyngeal cavity in fish, amphibians • Roof of nasal cavity in amniotes

  9. Primary Palate • Vomer • Palatine • Pterygoid

  10. Primary Palate • Examine Skull & Lower Jaw Components page

  11. Dermatocranium • Operculum

  12. Key Point • Describe dermatocranium bones in the shark…

  13. Axial Skeleton - Skull • Neurocranium • Dermatocranium • Splanchnocranium – Visceral skeleton

  14. Splanchnocranium • Supports & allows movement of jaws, gill, tongue • Associated with hearing • Ancient in evolution • Replacement bone

  15. Splanchnocranium • Typically 6 gill slits between • Visceral arches • A typical visceral arch that is gill in function has five segments • Pharyngobranchial • Epibranchial • Ceratobranchial • Hypobranchial • Basibranchial

  16. Splanchnocranium • Mandibular arch = Visceral Arch I • Palatoquadrate • Mandibular = Meckel’s Cartilage

  17. Splanchnocranium • Hyoid arch = Visceral arch II • Hyomandibula • Ceratohyal • Basihyal

  18. Interrelationships • The neurocranium, dermatocranium and splanchnocranium eventually becomes intimately associated to form one single, firm skull

  19. Key Point Describe the origin of jaws from this picture

  20. Key Point • The three main components of the cranium are:

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