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• Muscle tissue


  Composed of specialized cells containing contractile proteins that generate forces for cellular contraction and movement
• Muscle cells


  • Contain contractile proteins (actin and myosin) that slide past one another to produce contraction
  • Most muscle cells are of mesodermal origin
• Myocytes


  Cells that make up muscle tissue
• Muscle fibers


  • Elongated structure in one direction
• Functions of Muscular Tissue

  • Movement
  • Maintain posture
  • Heat generation
  • Stabilize joints
  • Move substances within the body
• Types of Muscle Tissues

  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
• Skeletal muscle


  • Found covering the skeleton and attached to bones
  • Muscle fibers are very long, cylindrical, striated, and multinucleated
  • Fibers are arranged parallel to each other
  • Have alternate dark and light bands (cross-striations)
• Myofibrils


  Contractile elements within muscle fibers
• Sarcomere


  Fundamental contractile unit of muscle
• Myofilaments


  Contain thick (myosin) and thin (actin) filaments
• Sarcolemma


  • Cell membrane surrounding muscle fibers
• Sarcoplasm


  • Cytoplasm of muscle fiber containing mitochondria, sarcoplasmic reticulum, Golgi body, but lacking centrioles
• Smooth muscle


  • Non-striated, forms walls of hollow organs and tubes
  • Cells are spindle-shaped with single, centrally located nuclei
  • Contains thick, thin, and intermediate filaments
• Cardiac muscle


  • Found only in the heart, resembles both skeletal and smooth muscle
  • Cells are short, branched, and striated
  • Cells are connected by intercalated discs which allow electrical activity to spread between cells
  • Cells contain numerous mitochondria for aerobic metabolism
  • Contractions are controlled by pacemaker cells
• Layers of the heart wall

  • Endocardium (inner lining)
  • Myocardium (middle layer)
  • Epicardium (outer layer)