An external layer of compact Bone surrounds a central area of spongy Bone, except at the marrow cavity.

骨的外层为质密的骨皮质，包围着海绵状骨松质中心区（不算骨髓腔）。

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An external layer of compact Bone surrounds a central area of spongy Bone, except at the marrow cavity.

骨的外层为质密的骨皮质，包围着海绵状骨松质中心区（不算骨髓腔）。

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