Which condition involves the loss of muscle control and strength due to the nervous system's impairment?

Myopathy is the correct choice as it specifically refers to a group of diseases that directly affect muscle tissue, leading to muscle weakness and impaired control. These conditions stem from intrinsic issues within the muscle fibers themselves rather than neurological pathways. The loss of strength and control in myopathy is due to damage or dysfunction of the muscles, which can occur from various causes, including genetic factors, inflammatory processes, or metabolic disorders.

While neuritis pertains to inflammation of the nerves, resulting in symptoms related to nerve function rather than direct muscle impairment, and neuropathy generally involves damage to the peripheral nerves, affecting sensation and leading to pain, weakness, or numbness, neither directly describes conditions that primarily result in muscle control and strength loss. Fibromyalgia encompasses widespread musculoskeletal pain and fatigue without identifiable inflammation or neuromuscular damage, focusing more on a syndrome of chronic pain rather than specific muscle dysfunction or neurological impairment. Therefore, myopathy is the condition that most accurately describes the impairment of muscle control and strength due to inherent muscle issues.