1. 1. Skeletal System: Skull Vhi Ann J Bajardo
2. 2. Cranial Skeleton is of three parts: Vhi Ann J Bajardo CRANIAL SKELETON Chondrocranium Splanchnocranium Dermatocranium
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4. 4. BLUE- Chondrocranium YELLOW- Splanchnocranium PINK- Dermatocranium Vhi Ann J Bajardo
5. 5. -elements found at the back of the vertebrae Nineteenth century morphologists propose that the vertebral column is the ancient ancestors of the chondrocranium. -neural crest cells and mesenchyme cells differentiate to form chondrocranium Vhi Ann J Bajardo
6. 6. cos + cos = 2 cos 1 2 + cos 1 2 Vhi Ann J Bajardo
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8. 8. neural crest cells contributions to the skull Vhi Ann J Bajardo
9. 9. -elements contribute to filter-feeding surfaces (Amphioxus), jaws and hyoid apparatus (Gnathostomes) -neural crest cells arise to form splanchnocranium Vhi Ann J Bajardo
10. 10. BLUE- Chondrocranium YELLOW- Splanchnocranium PINK- Dermatocranium Vhi Ann J Bajardo THE PARTS OF CRANIAL SKELETON shown in FIGURE 7.1
11. 11. Derivatives of Neural Crest Cells Protochordates NCC migrate to the body wall from the neural tube NCC differentiates into pigment cells Vertebrates NCC moves into the walls of pharynx NCC differentiates into jaws and gill arches Vhi Ann J Bajardo
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13. 13. a. ORIGIN OF JAWS -an anterior pair of gill arches gave rise to jaws -branchial arch musculature were transformed and modified into musculature of the jaws Divisions of mandibular arch of jawless fishes: Neurocranium (dorsal) Mandible (ventral) Vhi Ann J Bajardo
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15. 15. Embryology of Pharyngeal Arches Protochordates Pharyngeal arches rises from the mesoderm Most Vertebrates Pharyngeal arches rises from neural crest cells Vhi Ann J Bajardo
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17. 17. b. TYPES OF JAW ATTACHMENTS The points at which the jaws attach to the rest of the skull defines the type of jaw attachment Vhi Ann J Bajardo
18. 18. Jaw Attachment How Jaws are Attached Vertebrates Paleostyly no arches attach to the skull agnathans Euautostyly mandibular arch suspended from the skull acanthodians, placoderms Amphistyly jaws attached through ligament and hyomandibula extinct sharks, rhipistians, osteichthyans Hyostyly mandibular arch attached through hyomandibula modern bony fishes, extant sharks Metautostyly jaws attached directly to braincase through quadrate amphibians, reptiles, birds Craniostyly upper jaw incorporated to the braincase; lower jaw suspended through dermal squamosal bone mammals Vhi Ann J Bajardo
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20. 20. -consists of dermal bones contributing the skull -forms sides and roof of the skull -mesenchymal and ectomesenchymal tissues of the dermis Vhi Ann J Bajardo
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23. 23. Braincase- Jaws- Hyoid Apparatus- supports the tongue and the floor of the mouth Vhi Ann J Bajardo OVERVIEW
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25. 25. -movement between the upper jaw and the braincase about joints between them Cranial kinesis: movement between the upper jaw and braincase advantages: provides a way to change the size and configuration of the mouth rapidly optimize biting and rapid feeding. disadvantages: lose force, difficult to optimize apposition of occlusive surfaces. Vhi Ann J Bajardo CRANIAL KINESIS
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