All sesamoid bones form directly from the connective tissue found in tendons and ligaments. By contrast, the hyoid bone forms from a cartilaginous precursor like most other bones in the body.

How are sesamoid bones formed?

Sesamoid bones form within tendons in regions that wrap around bony prominences. They are common in humans but variable in number. Sesamoid development is mediated epigenetically by local mechanical forces associated with skeletal geometry, posture, and muscular activity.

What are sesamoid bones made up of?

cartilages or partly ossified as sesamoid bones (small, flat bones developed in tendons that move over bony surfaces). Parts of the synovial layer project into the cavity to form fatty pads. In a few diarthroses the fibrous layer also projects inward to become intra-articular disks, or menisci.