Muscletissue

Muscletissue is a specialized body tissue composed of contractile cells that enable movement, posture maintenance, and heat production. It comprises the majority of muscle mass in vertebrates and interacts closely with nerves, blood vessels, and connective tissue.

There are three main types: skeletal, cardiac, and smooth. Skeletal muscle consists of long, multinucleated fibers with striations and is mainly under voluntary control. Cardiac muscle, found in the heart, is striated but involuntary and features intercalated discs that synchronize contractions. Smooth muscle is non-striated and involuntary, lining hollow organs and vessels.

Muscle fibers contain myofibrils arranged into sarcomeres, the basic contractile units. Contraction uses actin and myosin filaments; calcium regulates activity through a process called excitation-contraction coupling, initiated by nervous input.

Developmentally, muscle tissue forms from mesodermal cells via myogenesis, with myoblasts fusing to form fibers. Satellite cells contribute to growth and repair, though regeneration is limited in adult muscle, and aging can lead to sarcopenia.

Connective tissue organizes muscle into units: the epimysium surrounds the whole muscle, the perimysium encases fascicles, and the endomysium envelops individual fibers. A rich vascular and neural supply supports metabolism and control.

Clinical relevance includes muscular dystrophies, inflammatory myopathies, cramps, and fibrosis after injury. Understanding muscle tissue supports studies in physiology, anatomy, sports medicine, and pathology.