muskelvevets

Muskelvævets, in Danish, refers to muscle tissue, the soft tissue responsible for producing force and movement in animals. It is highly organized for contraction and energy use, and it forms the bulk of muscles that move the skeleton, regulate organ systems, and support posture.

There are three main types of muscle tissue. Skeletal muscle is striated and under voluntary control; it attaches to bones and enables rapid, powerful movements. Smooth muscle is non-striated and involuntary, found in the walls of hollow organs and vessels, where it controls diameter and flow. Cardiac muscle is striated and involuntary, making up the heart; its cells are connected by intercalated discs that coordinate rhythmic contractions.

Muscle tissue is composed of muscle fibers (muscle cells) organized into larger bundles. Each fiber contains myofibrils, which are made of repeating sarcomeres—the basic contractile units. Sarcomeres contain actin and myosin filaments that slide past each other during contraction, powered by adenosine triphosphate (ATP) and regulated by calcium ions. Connective tissue layers (endomysium, perimysium, epimysium) surround fibers and fascicles, transmitting force to tendons and bones.

Development and regeneration rely on myogenesis from mesodermal precursor cells, with satellite cells playing a key role in repair. Skeletal muscle can grow in size (hypertrophy) in response to training, while regenerative capacity diminishes with age. Cardiac and smooth muscles have more limited regenerative abilities.

Clinical relevance includes conditions such as muscular dystrophy, inflammatory or metabolic myopathies, and age-related sarcopenia, all of which affect muscle structure or function. Proper physical activity and nutrition support muscle health and function across the lifespan.