Biology / Unit 13 Bio 3093 short lesson, about 20 seconds
Compact versus Spongy Bone
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The idea
Compact bone forms a dense outer layer resisting bending stress, while spongy bone forms a lighter, porous inner lattice that reduces weight without sacrificing strength.
In practice
A long bone's shaft is mostly compact bone, while its ends contain more spongy bone to absorb joint stress.
Where people slip
Spongy bone is not weak bone — its lattice geometry distributes stress efficiently at lower mass.
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