Which statements characterize the microscopic arrangement of spongy bone?
A. It contains no osteons. B. It contains concentric lamellae. C. It contains parallel lamellae. D. It contains many osteons.
The Correct Answer and Explanation is :
The correct statements that characterize the microscopic arrangement of spongy bone are:
A. It contains no osteons.
C. It contains parallel lamellae.
Explanation:
Spongy bone, also known as cancellous or trabecular bone, has a distinct structure compared to compact bone. One of its defining features is that it contains no osteons (option A). Osteons, also referred to as Haversian systems, are the fundamental functional units of compact bone and consist of a central canal surrounded by concentric layers of lamellae (the thin plates of bone matrix). In spongy bone, the structural arrangement is quite different; instead of osteons, it consists of a network of trabeculae, which are thin, rod-like or plate-like structures. This arrangement allows spongy bone to provide strength while being lightweight and facilitating the housing of bone marrow.
Additionally, spongy bone does contain parallel lamellae (option C), which are layers of bone matrix that run parallel to one another within the trabeculae. This lamellar structure contributes to the mechanical stability and strength of the bone while also allowing for spaces in between where bone marrow can be found. These spaces are critical as they provide a site for hematopoiesis, the production of blood cells.
On the other hand, B. It contains concentric lamellae is more characteristic of compact bone, where lamellae are arranged concentrically around a central canal, forming the osteons. D. It contains many osteons is also not true for spongy bone, as the trabecular network replaces the osteonal structure found in compact bone.
In summary, the unique arrangement of spongy bone, lacking osteons and featuring parallel lamellae, allows it to effectively fulfill its role in supporting the skeletal system while also providing essential functions related to blood cell production.