Which type of bone comprises the vertebrae and pelvic girdle?

The type of bone that comprises the vertebrae and pelvic girdle is classified as irregular bone. Irregular bones are characterized by their complex shapes that do not fit into the other categories of bone structure such as long, short, or flat bones. The vertebrae have a unique structure that supports the spine and protects the spinal cord, while the pelvic girdle connects the spine to the lower limbs and supports the weight of the upper body. These structures require a specific design to accommodate various functions, including weight-bearing, movement, and protection of internal organs.

In terms of anatomy, irregular bones often provide sites for muscle attachment and contribute to the overall framework of the body. Their diverse shapes and sizes allow for multiple functionalities, making them essential in the skeletal system. This definition and the functional requirements underscore why the vertebrae and pelvic girdle are classified as irregular bones.