quadriceps femoris
The Gastrocnemius. There is another muscle involved in plantar flexion. The soleus and the tibialus posterior maintains the arch. The only one that does both actions, though, is the Gastrocnemius.
Posterior interosseus nerve, one of the two terminal branches of Radial and the Radial itself (it supply only one muscle)
The only knee flexor that originates superior to the acetablulum is the sartorius muscle
Extensor digitorum longus (lateral 4 toes), Extensor digitorum brevis (medial 4 toes) and extensor hallucis longus (big toe only)
The only muscle of the leg that is made up of three muscles are the hamstrings.
posterior posterior
When one muscle pulls, the other muscle relaxes.
extensor digitorum, extensor indicis, extensor digiti minimi, flexor digitorum superficialis, and the flexor digitorum profundus. There are also extrinsic muscles that work only in the thumb; these include the flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and adbuctor pollicis longus
There is nothing really called 'cardiac smooth muscle'. Cardiac muscle is striated like skeletal muscle but it is not under your control like skeletal muscle is. It acts more like smooth muscle because of this reason. But we only use the terms smooth muscle, striated (skeletal) muscle or cardiac muscle.
Structure of a muscle cell
Yes. An x-ray shows only bones; an MRI shows bones+tissues+muscle.
If you mean hyperadduction of the joint at the knee, it is stretching the muscle on the top of your thigh which is called the gastrocnemius.