What is a muscle contusion?

A muscle contusion, often referred to as a bruise, occurs due to a direct impact to the muscle, which results in damage to the muscle fibers and associated blood vessels. This impact leads to bleeding within the muscle tissue, disrupting circulation in the affected area and causing swelling, pain, and tenderness. The key aspect of a contusion is that it specifically arises from an acute trauma, causing localized damage and inflammation rather than tearing the fibers completely or resulting from chronic conditions.

The other options address different types of injuries or conditions. For example, a tear of the muscle fibers refers to a strain, which is distinct from a contusion as it involves a complete or partial rupture rather than just bruising. Chronic conditions affecting muscle flexibility and forms of degeneration due to age do not relate to the acute nature and impact mechanism of a muscle contusion, emphasizing why the choice of a muscle contusion being an injury caused by an impact is accurate.