Muscolo

Muscolo is the term used for the soft tissue in animals that contracts to generate force and movement. In humans, muscle tissue is categorized into skeletal muscle (voluntary, striated, attached to bones), smooth muscle (involuntary, found in walls of hollow organs and vessels), and cardiac muscle (found in the heart). Skeletal muscles make up a large part of body mass and enable voluntary movement, posture, and locomotion.

Muscle structure includes muscle fibers, which are long, multinucleated cells organized into fascicles and wrapped by connective tissue layers (endomysium, perimysium, and epimysium). Within fibers lie myofibrils containing sarcomeres, the contractile units built from actin and myosin. Contraction follows the sliding filament theory: calcium ions enable cross-bridge cycling between actin and myosin, shortening the sarcomeres and thereby the whole muscle.

Control and metabolism: Skeletal muscles are innervated by motor neurons and can respond to voluntary commands. Smooth and cardiac muscles are regulated mainly by the autonomic nervous system and hormonal signals. ATP provides the energy for contraction, with mitochondria supplying aerobic energy and other pathways supporting quick, short bursts. Muscles adapt with training (hypertrophy) and disuse (atrophy); satellite cells participate in repair and regeneration.

Function and health: Beyond moving the skeleton, muscles generate heat, support posture, and help regulate circulation and metabolism. Common clinical issues include strains or cramps, inflammatory myopathies, and genetic disorders such as muscular dystrophies. Aging is associated with sarcopenia, a decline in muscle mass and strength. The term muscolo derives from Latin musculus, meaning “little mouse,” a reference to the appearance of moving muscles.