Axial Skeleton Ribs

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Axial Skeleton - Ribs

• Function
• Protection
• Respiration
• Phylogeny - new
• Endochondral

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Ribs

• Dorsal ribs separate dorsal and ventral muscle
  mass
• Ventral ribs are in the body wall

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Ribs

• Monocipital (snakes monotremes)
• Bicipital
• Dorsal head tuberculum
• Ventral head capitulum

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Ribs

• Costal vertebral ribs
• Sternal costal cartilage

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Ribs - Fish

• Some have no ribs
• Some have dorsal ribs only (sharks)
• Some have ventral ribs
• Some have dorsal ventral ribs

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Ribs - Amphibians

• Short in anurans and urodeles
• Long in apodans

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Ribs - Reptiles

• Typically short in neck and long in trunk
• Turtles fused to carapace
• Snakes long and curved
• Crocodiles Gastralia are NOT ribs

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Turtle skeleton
Carapace
Fused vertebrae
Ribs
Plastron
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Ribs - Birds

• Costal Sternal Ribs
• Uncinate Processes for muscle attachment

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Ribs - Mammals

• Thoracic (12 in human, 13 in cat)
• True rib
• False rib
• Floating rib

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Sternum

• Needed for stronger more mobile forelimbs
• Tetrapod feature only
• Function protection, strengthens body wall,
  attaches muscles, rib attachment
• Endochondral bone

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Sternum - amphibians

• Frogs toads ossified, but poor
• Urodeles flimsy if present
• Caecilians - none

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Sternum - reptiles

• Lizards large
• Crocodiles large cartilaginous plate
• Snakes none
• Turtles none needed

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Sternum - birds

• Keel
• Carina
• For muscle attachment

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Sternum - Mammal

• Segments
• Xiphoid process is caudal-most segment

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