Microvilli (singular: microvillus) are microscopic cellular membrane protrusions that increase the surface area of cells and minimize any increase in volume, and are involved in a wide variety of functions, including absorption, secretion, cellular adhesion, and mechanotransduction. 1 Locations.
Activities such as bending the knee, kicking or running can worsen the pain. The calf muscle, or gastrocnemius, aids in propelling you forward while walking or running. A strain at the upper end of the gastrocnemius causes pain in the back of the knee that worsens with knee bending or rising to your tiptoes. The popliteus muscle helps stabilize the knee joint during movement. Injury to this muscle can be challenging to diagnose.
Because the plantaris doesn't contribute much force in bending the knee, a tear in this muscle may not seriously affect your knee function. However, a severe plantaris strain can cause significant pain, usually at the back of your calf rather than near the knee. A plantaris strain can occur alone or accompany a gastrocnemius strain or a tear of the anterior cruciate ligament (ACL), a major, stabilizing ligament in the knee.