Which bones are classified as irregular bones?

Irregular bones are characterized by their complex shapes that do not fit into the categories of long, short, or flat bones. The vertebrae and certain facial bones exemplify this classification well.

The vertebrae, for instance, have unique structures that allow them to support the spinal column and protect the spinal cord while contributing to a flexible posture. Similarly, some facial bones, such as the maxilla or mandible, also possess irregular shapes that serve to accommodate various functions, including housing the teeth or forming the eye sockets.

In contrast, options involving the bones of the fingers and toes, upper and lower legs, or the wrist and ankle represent long and short bones, which possess more uniform shapes designed for specific movements and functions. Long bones, like those in the legs, primarily facilitate support and movement, while short bones assist with stability and support in confined spaces, such as the wrist and ankle. Therefore, the classification of vertebrae and some facial bones as irregular is based on their distinct, complex shapes, contrasting with the more standardized forms of the bones described in the other options.