Page 117 - 84 human physiolofy part-1

The Muscular System

Muscle atrophy resulting from disease rather than disuse is generally one of two types, that
resulting from damage to the nerves that supply the muscles, and disease of the muscle itself. Examples
of diseases affecting the nerves that control muscles would be poliomyelitis, amyotrophic lateral
sclerosis (ALS or Lou Gehrig's disease), and Guillain-Barre syndrome. Examples of diseases affecting
primarily the muscles would include muscular dystrophy, myotonia congenita, and myotonic dystrophy
as well as other congenital, inflammatory or metabolic myopathies.

Even minor muscle atrophy usually results in some loss of mobility or power.

Common Causes

• some atrophy that occurs normally with aging
• cerebrovascular accident (stroke)
• spinal cord injury
• peripheral nerve injury (peripheral neuropathy)
• other injury
• prolonged immobilization
• osteoarthritis
• rheumatoid arthritis
• prolonged corticosteroid therapy
• diabetes (diabetic neuropathy)
• burns
• poliomyelitis
• amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease)
• Guillain-Barre syndrome
• muscular dystrophy
• myotonia congenita
• myotonic dystrophy
• myopathy

Muscular Dystrophy

Muscular dystrophy (MD) is a group of rare inherited muscle diseases in which muscle fibers are
unusually susceptible to damage. Muscles, primarily voluntary muscles, become progressively weaker.
In the late stages of muscular dystrophy, fat and connective tissue are often replaced by muscle fibers.
In some types of muscular dystrophy, heart muscles, other involuntary muscles and other organs are
affected.

The most common types of muscular dystrophy appear to be due to a genetic deficiency of the
muscle protein dystrophin. There's no cure for muscular dystrophy, but medications and therapy can
slow the course of the disease.

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