Skeletal and Muscular Disorders :
Muscular dystrophy : It is inherited muscle destroying disease. It is characterized by degeneration of individual muscle fibre, which leads to progressive atrophy of the skeletal muscle. Usually the voluntary skeletal muscles are weakened equally on both sides of the body, whereas the internal muscles, such as the diaphragm, are not affected. The most common form of muscular dystrophy is Duchenne type.
Osteoporosis : It is an age dependent disease. In women, after menopause, the estrogen secretion becomes less causing loss of calcium. The bones become porous due to low bone mass. Skeleton fails to withstand the stress of body. It is also caused by deficiency of vitamin D, calcium, sex hormones and thyrocalcitonin.
Arthritis : It is characterized by inflammation of joints. Inflammation, pain and stiffness may also be present in adjacent parts of the body, such as the muscles near the joint.
There are 3 types.
1. Gouty arthritis (gout) : It is caused due to excessive accumulation of uric acid in the body due to excessive production or inability to excrete. It gets deposited in joints and leads to severe pain.
2. Osteoarthritis : It is characterized by degeneration of the cartilage pad. Joints of knees, hands and spine are usually affected by this disease.
3. Rheumatoid arthritis : It is characterized by the inflammation of synovial membrane. The membrane thickens and synovial fluid increases, exerting pressure that causes severe pain. The membrane then starts. secreting abnormal granules, called pannus, which cause erosion of cartilage.
Myasthenia gravis:
This is an auto-immune condition of unknown origin. Anti-bodies are produced which block and bind to the acetylcholine receptors of neuro-muscular junction. Thus transmission of nerve impulses to the muscle fibers is blocked. This causes progressive and extensive muscle weakness. It may affect the eye and eyelid movements, facial expression and swallowing. The degree of muscle weakness varies from the local to general. Example-eyelid muscles (ptosis - drooping of eyelid), diplopia or double vision, difficulty in swallowing, chewing and speech.
Tetany :
Tetany is a state in which impulses from nerve arrive to the skeletal muscle in rapid succession, resulting in summation of action potential causing steady contractions. One of the common causes of tetany is low serum levels of calcium because of reduced activity of parathyroid glands. The parients suffering from tetany exhibit persistent contraction of skeletal muscles.