Parents of a toddler boy noticed he began to walk on his toes, was falling often, and struggled to stand back up. Over time it became more difficult for him to life his knees high, which affected his ability to run. At age six, doctors noted that he had progressive muscle wasting. Over more time, his trunk muscles began to weaken along with the others, and as a result he developed a protuberant abdomen. Lordosis become evident as well. He was confined to a wheelchair at age eight and he began to develop muscular contractures. 

1. This toddler boy has an x-linked recessive disorder that results in progressive muscular weakness and muscle contractures. What is it called? What does it mean to be x-linked?

2. Define the term "dystrophy". Why is this term appropriate when describing the boy's case?

3. The boy in this case first showed signs of his disorder when he began walking on his toes. What are ALL of the muscles that are used to walk on his toes? (Hint: there are many answers here). 

4. Another common problem seen in patients with this disorder is lordosis and abdominal protuberance. What muscles would become weakened to cause abdominal protuberance? (Hint: there are many answers here too!).