Sesamoid Bones

Sesamoid bones are unique in that they are small bones that are embedded within tendons. They play a crucial role in directing forces away from other bones or muscles and tendons. The structure of these bones consists of a hard outer layer of compact bone and a spongy bone inner layer, providing them with the necessary strength and flexibility to perform their function.

For example, the kneecap, also known as the patella, is a sesamoid bone that guides the tendons over the gap between the femur and the tibia and fibula, thus preventing the tendons from getting caught when we bend and stretch our legs. This allows for more force to be applied by the leg muscles.

Figure 1: The patella is a sesamoid bone found in the knee.