Many of the symptoms you describe are vague and could be due to a number of things including Provera. Some of the common side effects of this medication include weight gain, weak bones, headaches, fatigue, swelling. These symptoms could also be caused by a number of things such as thyroid problems.
Myofibrils are assembled of repeated structures called sarcomeres â the smallest functional unit of muscle fiber. Each sarcomere is formed of actin (called thin) and myosin (called thick) filaments arranged in a precise order and of protein complexes which support the filament structures.
The functional units of skeletal muscle are not individual muscle fibers, but larger systems called motor units. The motor unit consists of a motor neuron and the group of skeletal muscle fibers which it innervates. A single skeletal muscle is composed of many thousands to millions of long, narrow contractile cells called muscle fibers (Fig-1). These fibers are clustered together in parallel bundles called fasciculi.