Identify the structure in the square.

Identify the structure in the square.

• A. Osteon of Compact Bone
• B. Osteon of Spongy Bone
• C. Trabeculae of Spongy Bone
• D. None of the Above

Answer: (A)

Recognize that compact bone’s basic functional unit is the osteon, a tightly organized cylinder oriented along the bone’s length. An osteon features concentric lamellae—thin calcified rings—that surround a central Haversian canal containing blood vessels and nerves. This arrangement gives compact bone its dense, uniform appearance. The image showing rings around a central canal is typical of an osteon. In contrast, spongy bone lacks these cylindrical units; it is made of trabeculae—needle-like or plate-like elements forming a porous network with spaces for marrow. Since the square image displays concentric rings around a central canal, the highlighted structure is an osteon of compact bone. If we were looking at spongy bone, we’d expect a lattice of trabeculae rather than a central hollow canal.

Recognize that compact bone’s basic functional unit is the osteon, a tightly organized cylinder oriented along the bone’s length. An osteon features concentric lamellae—thin calcified rings—that surround a central Haversian canal containing blood vessels and nerves. This arrangement gives compact bone its dense, uniform appearance. The image showing rings around a central canal is typical of an osteon. In contrast, spongy bone lacks these cylindrical units; it is made of trabeculae—needle-like or plate-like elements forming a porous network with spaces for marrow. Since the square image displays concentric rings around a central canal, the highlighted structure is an osteon of compact bone. If we were looking at spongy bone, we’d expect a lattice of trabeculae rather than a central hollow canal.