The coxal bone, also known as the hip bone, is classified as an irregular bone. Irregular bones are bones that do not fit into the categories of long, short, flat, or sesamoid bones due to their complex shapes. The coxal bone is a large, irregularly shaped bone that forms part of the pelvic girdle. It is composed of three parts: the ilium, ischium, and pubis, which fuse together during development.
Irregular bones, like the coxal bone, often have a variety of functions, including providing structural support and protection for internal organs. In the case of the coxal bone, it plays a crucial role in supporting the weight of the upper body when sitting and standing, and it also protects the pelvic organs.