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If we divide any of the long bones longitudinally, we find two kinds of structure, the hard or compact, and the alveolar or spongy. Indeed there is no bone that does not exhibit to some extend both of these structures; the compact forming its external, and the spongy its internal part. These two formations are clearly seen in the bones which compose the skull, as in the following cut, with the spongy or cancellated structure between them. This serves to illustrate the structure of all of the flat bones.

Bone Structure

If we divide any of the long bones longitudinally, we find two kinds of structure, the hard or compact,…

The humerus bisected lengthwise. Labels: a, marrow-cavity; b, hard bone; c, spongy bone; d, articular cartilage.

Bisection of the Humerus

The humerus bisected lengthwise. Labels: a, marrow-cavity; b, hard bone; c, spongy bone; d, articular…

Longitudinal section of humerus showing relation of compact and spongy bone.

Longitudinal Section of Humerus

Longitudinal section of humerus showing relation of compact and spongy bone.

The thigh bone cut through the middle. Labels: b, hard bone; h, d, spongy bone; ma, marrow.

Thigh Bone

The thigh bone cut through the middle. Labels: b, hard bone; h, d, spongy bone; ma, marrow.

The inner surface (A) and outer surface (B) of the right inferior turbinated bone.

Inferior Turbinated Bone

The inner surface (A) and outer surface (B) of the right inferior turbinated bone.