They contain a layer of spongy bone covered by a thin layer of compact bone. As the name suggests, they are mostly flat and curved, having a thin plate-like formation. The word sesamoid sounds kind of like sesame seed, and that’s because these seed-shaped bones get their name from a Greek word that means “resembling a sesame seed.” There are 4 sesamoid bones in the adult skeleton:Īdditional sesamoid bones can sometimes form on the tarsal, metatarsal, or incus bones, but this can vary per individual.įlat bones provide protection to vital organs. Sesamoid bones are a special subcategory of short bones that are embedded in tendons. There are 28 short bones in the adult skeleton, consisting of the tarsals and most of the carpals: They consist mostly of spongy bone that is covered by a thin layer of compact bone. Short bones have approximately the same length and width, which gives them a cube-like appearance. There are 90 long bones in the adult skeleton, consisting mostly of the bones of the upper and lower extremities, as well as the clavicle bones: These bones are going to have a shaft made primarily of compact bone, and two bulky ends, which often contain spongy bone. These bones can vary in length (short or long), but the key characteristic is that they are longer than they are wide.

We also have two minor categories of bones: sesamoid bones and sutural bones.įirst, I’ll talk about the long bones, which is the most common type of bone. We have four major categories: long bones, short bones, flat bones, irregular bones.

Is the sternum a flat bone