Popliteus muscle assists in flexing the leg upon the thigh; when the leg is flexed, it will rotate the tibia inward. It is especially called into action at the beginning of the act of bending the knee, inasmuch as it produces the slight inward rotation of the tibia, which is essential in the early stage of this movement. When the knee is in full extension, the femur slightly medially rotates on the tibia to lock the knee joint in place. Popliteus is often referred to as the "Key" to unlocking the knee since it begins knee flexion by laterally rotating the femur
Fibrous joint joint, form the only non-sutured joints in the skull. Most sutures are named for the bones they articulate, but some have special names of their own. A syndesmosis is a slightly movable fibrous joint in which bones such as the tibia and fibula are joined together by connective tissue. Examples include the distal tibia fibular joint as well as the radioulnar joint. Injuries to the ankle syndesmosis are commonly known as a "high ankle sprain". Although the syndesmosis is a joint, in the literature the term syndesmotic injury is used to describe injury of the syndesmotic ligaments. It comes from