Tendon the Achilles tendon stretches as the ankle joint dorsiflexes. During the last portion of the stride, as the foot plantar-flexes (pointing the toes down), the stored elastic energy is released. Furthermore, because the tendon stretches, the muscle is able to function with less or even no change in length, allowing the muscle to generate greater force. The mechanical properties of the tendon are dependent on the collagen fiber diameter and orientation. The collagen fibrils are parallel to each other and closely packed, but show a wave-like appearance due to planar undulations, or crimps, on a scale of several micrometers. In
Quadriceps tendon Quadriceps tendon In human anatomy, the quadriceps tendon allows the quadriceps femoris muscles ("rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius") to converge on the superior aspects of the patella on the anterior of the thigh, which continues as the patellar ligament. A tendon connects muscle to bone, while a ligament connects bone to bone. The quadriceps tendon works with the quadriceps to extend the leg. Injuries are common to this tendon, with tears, either partial or complete, being the most common. If the quadriceps tendon is completely torn, surgery will be required to regain function of the knee.