Skeletal Muscle Structure and Function

Skeletal Muscle Structure

• Skeletal muscle fibers are elongated and multinucleated, containing 100-300 nuclei.
• The nuclei are located peripherally.
• The fibers are arranged in a non-branched, parallel fashion.
• Connective tissue is present between the fibers.
• The sarcoplasm contains numerous myofibrils, giving the muscle a striated appearance.

Skeletal Muscle Fiber Types

• Type I:
  • Red in color due to the presence of myoglobin.
  • Slow twitch and slow fatiguing fibers.
  • Utilize oxidative metabolism for energy production.
  • Rich in mitochondria.
• Type II:
  • White in color.
  • Fast twitch and fast fatiguing fibers.
  • Utilize glycolysis for energy production.
  • Two subtypes exist.

Musculoskeletal Examination

• Skeletal muscle examination includes:
  • Assessing muscle color.
  • Evaluating muscle volume, comparing to the opposite side if bilateral.
  • Observing muscle texture and appearance.
  • Testing muscle response to stimuli.
  • Performing histopathology.

Skeletal Muscle Disease

• Two types of possible changes:
  • Neuropathic: Failure in nerve signal transmission.
  • Myopathic: Failure in the muscle cell itself.

Possible Clinical Signs of Skeletal Muscle Disease

• Atrophy
• Hypertrophy
• Swelling
• Weakness
• Pain
• Muscle spasms
• Abnormal gait

Disease Portal Entries for Skeletal Muscle Disease:

• Wounds
• Intramuscular injections
• Bone fractures causing trauma
• External pressure
• Blood pathogens, toxins, autoantibodies (diseases that affect the skeletal muscle)

Skeletal Muscle Disease: Inflammatory

This category is not described further in the provided text.

This quiz explores the anatomy and physiology of skeletal muscle, including the structure of muscle fibers and the different types of skeletal muscle. Questions will cover the unique properties of Type I and Type II fibers as well as techniques used during musculoskeletal examinations.