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
Tibia Clausa Tibia Clausa A Tibia Clausa is a type of pipe organ pipe. It is a large-scale, stopped wood flute pipe, usually with a leathered lip. The rank was invented by Robert Hope-Jones. Tibia Clausas provides the basic foundation tone of the organ with few overtones or harmonics. The Tibia Clausa is arguably the most important rank of pipes in a theatre pipe organ, with some organs having as many as 5. The stop shares similarities with the "Bourdon" and the "Gedackt" found in some church pipe organs. In the 18th and 19th centuries, Tibia Clausa was sometimes used as an