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Chapter 8
Muscular System
| Term | Definition |
|---|---|
| Skeletal Muscle | also called striated or voluntary muscle; has crosswise stripes or striations; contractions can be voluntarily controlled |
| Cardiac Muscle | composes bulk of heart; Cardiac fibers are branched; has dark bands called intercalated disks |
| Nonstriated muscle, or involuntary muscle | also called smooth or visceral muscle; lacks striations when seen under a microscope, appears smooth; Found in walls of hollow structures like the digestive tract, blood vessels, etc |
| Regions of a Skeletal Muscle | Origin, Insertion, Body |
| Bursae | small synovial-lined sacs containing a small amount of synovial fluid; located between some tendons and underlying bones |
| myosin | thick myofilaments |
| actin | thin myofilaments |
| sarcomeres | separated from each other by dark bands called Z lines |
| Prime Mover | mainly responsible for producing a given movement |
| Synergist | helps the prime mover produce a given movement |
| Antagonist | opposes the action of a prime mover in any given movement |
| Neuromuscular Junction (NMJ) | point of contact between a nerve ending and the muscle fiber |
| Motor Unit | combination of a motor neuron with the muscle fibers it controls |
| Threshold Stimulus | Minimal level of stimulation required to cause a muscle fiber to contract |
| "all of none" | Once stimulated by a threshold stimulus, a muscle fiber will contract completely |
| Flexion | Decreases an angle |
| Extension | Increases an angle |
| Abduction | Away from the midline |
| Adduction | Toward the midline |
| Rotation | Around an axis |
| Circumduction | Move distal end of a part in a circle |
| Supination & Pronation | Hand positions that result from twisting |
| Dorsiflexion & Plantar Flexion | Ankle movements (upward and downward foot movement) |
| Inversion & Eversion | Ankle movements (sideways) |