csontvázizomokat

Csontvázizom (skeletal muscle) is a type of striated muscle tissue that is attached to the skeleton and enables voluntary movement. Muscles are composed of bundles of elongated fibers (myocytes), which contain myofibrils with alternating light and dark bands called sarcomeres. These sarcomeres shorten when stimulated by motor neurons, allowing the muscle to generate force.

There are two main types of skeletal muscle fibers: red (slow-twitch) fibers, rich in mitochondria and capillaries, which sustain prolonged activity, and white (fast-twitch) fibers, which generate powerful, rapid contractions but fatigue more quickly. The proportion of each fiber type varies among individuals and can be altered through training.

Skeletal muscles receive motor innervation from the somatic nervous system via alpha motor neurons that release acetylcholine at the neuromuscular junction. The excitation–contraction coupling process involves the release of calcium from the sarcoplasmic reticulum, leading to cross‑bridge cycling between actin and myosin filaments. Muscle contraction can be modulated by hormone regulation, such as adrenaline enhancing calcium release, or by the neuromuscular pump aiding blood return.

Common conditions affecting skeletal muscle include muscular dystrophy, myasthenia gravis, and inflammatory myopathies such as polymyositis. Nutrient deficiencies (e.g., vitamin D) and genetic mutations can also impair muscle function.

Skeletal muscle is essential for locomotion, posture maintenance, respiration (via the diaphragm), and metabolic regulation by consuming glucose during contraction. Regular exercise stimulates hypertrophy and improves neuromuscular efficiency, thereby supporting overall health and well‑being.