axial skeleton - ribs function – protection – respiration phylogeny - new endochondral

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Axial Skeleton - Ribs Function Protection Respiration Phylogeny - new Endochondral

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Axial Skeleton - Ribs

Function– Protection– Respiration

Phylogeny - newEndochondral

Ribs

Dorsal ribs separate dorsal and ventral muscle mass

Ventral ribs are in the body wall

Ribs

Monocipital (snakes & monotremes)Bicipital

– Dorsal head = tuberculum– Ventral head = capitulum

Ribs

Costal = vertebral ribsSternal = costal cartilage

Ribs - Fish

Some have no ribsSome have dorsal ribs only (sharks)Some have ventral ribsSome have dorsal & ventral ribs

Ribs - Amphibians

Short in anurans and urodelesLong in apodans

Ribs - Reptiles

Typically short in neck and long in trunkTurtles – fused to carapaceSnakes – long and curvedCrocodiles – Gastralia are NOT ribs

Turtle skeletonCarapaceCarapace

PlastronPlastron

Fused vertebraeFused vertebrae

RibsRibs

Ribs - Birds

Costal & Sternal RibsUncinate Processes for muscle attachment

Ribs - Mammals

Thoracic (12 in human, 13 in cat)True ribFalse ribFloating rib

Sternum

Needed for stronger & more mobile forelimbs

Tetrapod feature onlyFunction – protection, strengthens body

wall, attaches muscles, rib attachmentEndochondral bone

Sternum - amphibians

Frogs & toads – ossified, but poorUrodeles – flimsy if presentCaecilians - none

Sternum - reptiles

Lizards – largeCrocodiles – large cartilaginous plateSnakes – noneTurtles – none needed

Sternum - birds

KeelCarinaFor muscle attachment

Sternum - Mammal

SegmentsXiphoid process is caudal-most segment