Which condition is commonly associated with pain and tenderness in a muscle due to inflammation?

The correct answer is tendinitis, which is characterized by the inflammation of a tendon, the fibrous tissue that connects muscle to bone. When tendinitis occurs, it often results in pain, tenderness, and swelling in the affected area, as the inflammation affects the tendon involved in the muscle movement. This typically occurs in areas where the tendon is overused or stressed, leading to discomfort during activities that require the use of the affected muscle.

While conditions such as ectopic calcification, fasciitis, and tenosynovitis also involve inflammatory processes, they pertain to different anatomical structures or specific areas of the body. Ectopic calcification involves the abnormal deposition of calcium salts in soft tissues, which can cause pain but is not specifically tied to muscle tenderness. Fasciitis refers to inflammation of the fascia, the connective tissue surrounding muscles, which can result in pain but is distinct from muscle and tendon inflammation. Tenosynovitis specifically affects the synovial sheath surrounding tendons, leading to inflammation and pain but is a more localized condition compared to the broader impact of tendinitis on muscle and tendon interactions.