Muscle Physiology Case Histories - Case 5

Parents of a 3-year-old boy noticed that their son was walking "on his toes," had a waddling gait, fell frequently and had difficulty getting up again, and was not able to run because of the difficulty in raising his knees. At age five, there was progressive muscular weakness and muscle wasting. Weakness of the trunk muscles led to increased lordosis and a protuberant abdomen. At age nine, he was confined to a wheelchair. Contractures appeared, first in the feet, as the gastrocnemius muscles tightened.

1. This hereditary X-linked recessive disease characterized by progressive muscular weakness is .

2. What does dystrophy mean? Why is this term used to describe this case?

3. What muscles would be involved in walking "on the toes"? Which muscles are "weakening"?

4. Name the trunk muscles that weaken in certain cases of lordosis and abdominal protuberance.

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