Chapter 6 The Muscular System 201 Copyright Goodheart-Willcox Co., Inc. and drooping of the eyelids. Some forms of MD also affect the heart muscle, resulting in an irregular heartbeat. There are no known cures for the various muscular dystrophies the goal of treatment is to control symptoms. Some types of muscular dystrophy lead to a shortened life others cause little disability, allowing for a normal life span. Hernia A hernia is a balloon-like section of tissue that protrudes through a hole or weakened section of a muscle, most commonly in the abdomen. A hernia can be caused by heavy lifting, or by any activity or medical problem that increases pressure on the tissue. In most cases, however, no specific cause is evident. Some hernias are present at birth, and some occur in infants and children. A hernia that is present at birth may not become noticeable until later in life. Most hernias produce no symptoms, although some are accompanied by discomfort or pain that intensifies with heavy lifting or other activities that produce strain. A large hernia may strangulate, or cut off, the blood supply to the tissue inside the hernia. A strangulated hernia requires immediate surgery. Small hernias that cause no symptoms do not necessarily require treatment. Larger hernias and those that cause discomfort can be permanently remedied with surgery. SECTION 6.5 REVIEW Mini-Glossary contusion bruising or bleeding within a muscle as a result of an impact delayed-onset muscle soreness (DOMS) muscle pain that follows participation in a particularly long or strenuous activity begins 24–73 hours after activity and involves multiple, microscopic tears in the muscle tissue that cause inflammation, pain, swelling, and stiffness hernia a balloon-like section of tissue that protrudes through a hole or weakened section of a muscle muscle cramps moderate to severe muscle spasms that cause pain muscle strain an injury that occurs when a muscle is stretched beyond the limits to which it is accustomed muscular dystrophy (MD) a group of similar, inherited disorders characterized by progressively worsening muscle weakness and loss of muscle tissue myositis ossificans a condition in which a calcium mass forms within a muscle three to four weeks after a muscle injury shin splint pain that is localized to the anterior lower leg tendinitis inflammation of a tendon usually accompanied by pain and swelling tendinosis degeneration of a tendon believed to be caused by microtears in the tendon’s connective tissue Review Questions 1. What causes a muscle strain? 2. What can you do to increase your chances of avoiding muscle strains? 3. What is myositis ossificans? What problems can it cause? 4. What do shoulder, elbow, and shin injuries have in common? 5. What is the main cause of DOMS? 6. Why is it important to treat chronic tendinitis? 7. What is believed to be the main cause of shin splints? 8. Name an activity often associated with hernias. 9. If obesity is a major cause of LBP, why do gymnasts experience this health problem? 10. How do poor body mechanics contribute to overuse injuries such as swimmer’s shoulder and tennis elbow? Describe and analyze the effect of torque in these injuries.