What defines irregular bones?

Irregular bones are characterized by their complex and varied shapes that do not fit into the other categories of bone types, such as long or flat bones. This complexity often relates to their specific functions, which can include protection of internal organs and serving as attachment points for muscles. For instance, the vertebrae in the spine are considered irregular bones because they protect the spinal cord while allowing for a range of motion and flexibility. Similarly, the pelvic bones are irregular in shape and play a crucial role in protecting reproductive organs and supporting weight during movement.

The other options describe different types of bones. Uniformly shaped bones refer to long or flat bones, which have simpler structures and functions, such as facilitation of movement or providing surface areas for muscle attachment rather than the complex roles seen with irregular bones.