Musculoskeletal Anatomy Key Term Review


Key Term



single muscle cell


myofiber contractile units


a single contractile unit

motor unit

one neuron and the muscle fibers it innervates

Type I

Slow-twitch; dominant fiber type for endurance/posture;

Type II

Fast-twitch; dominant fiber type for agility, quick actions


muscles that function to maintain motion within a target plane of motion


muscles that function to provide support a region while another area moves


loose, ubiquitous connective tissue


thick connective tissue that attaches muscle to bone. Myotendinous junction (where muscle connects to tendon) is the most common site of muscle strain


thick connective tissue that connects bones across joints; contributes to proprioception and pain perception

articular cartilage

avascular viscoelastic material that provide a smooth frictionless surface for joint motion


blend of fibrous and cartilaginous tissue that provides flexibility, toughness, and elasticity


  • Major contractile proteins in myofibrils are actin and myosin
  • Concentric muscle contraction (shortening) relies on ATP as its energy source to catalyze the myosin head bond to actin filaments.
  • Eccentric contraction involves the physical "breaking" of cross links between actin and myosin due to an applied load.
  • Hundreds of thousands of myofibrils use energy and interactions between actin and myosin to produce a shortening contraction resulting in isometric, single joint, or functional movement.
  • Muscle function and training will determine the efficiency and effectiveness of Type I and Type II fibers.


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