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Bone, joint, and muscle disorders

Bone diseases are conditions that result in the impairment of normal bone function and can make bones weak. Weak bones should not just be excused as a natural part of aging. Strong bones begin in childhood. People of all ages can improve their bone health. Bone is a connective tissue that contains a hardened matrix of mineral salts and collagen fibers. Its cells include osteocytes, which are embedded within lacunae, and the free-roaming osteoblasts and osteoclasts. In

addition to providing shape and structure to the body, bone stores mineral salts and aids information of blood cells under an outer "periosteum" layer, compact bone, a hard mass made up of layers of bone cell (osteocyte) tissue in concentric layers (Haversian system), forms the outer shell of most bones, surrounding inner spongy bone with its network of bony bars, and nerves. Bones support body structures, protect internal organs, and (in conjunction with muscles) facilitate movement; are also involved with cell formation, calcium metabolism, and mineral storage. The bones of an animal are, collectively, known as the skeleton.

In the very young, the skeleton is composed largely of cartilage and is therefore pliable, reducing the incidence of bone fracture and breakage in childhood. The inorganic, or mineral, content of bone is mainly calcium, phosphate and carbonate minerals. The organic content is a gelatinous material called collagen. As the body grows older, decreases in bone mass may lead to an increased vulnerability to fractures. Bone fractures heal naturally, although they are often aided through restriction of movement in the affected area. Bones assume a variety of sizes and shapes; however, all bone tissue has a three-layered composition. A spongy layer forms the interior. Long bones (such as those in the arms and legs) are hollow, the inner spaces being filled with marrow, important in the formation of blood cells. Surrounding the spongy, inner layer is a hard, compact layer that functions as the basic supportive tissue of the body. The outer layer is a tough membrane called the periosteum, which sheaths most bones. Although bone appears solid, it contains numerous microscopic canals permitting the passage of blood vessels and nerve fibers. Two types of bone are present in most bones: compact, which constitutes the shaft, and cancellous, an extremely strong variety which makes up the enlarged ends of the bone.

The most common bone disease is osteoporosis. Osteoporosis is characterized by low bone mass and deterioration of bone structure. Osteoporosis can be prevented, as well as diagnosed and treated. Osteoporosis is a silent disease until a fracture occur. Four times as many men and nearly three times as many women have osteoporosis than report having the disease. Low bone mass means that bones have less than optimal amounts of calcium and other minerals that make them strong. As a result of low bone mass, bones become weak and break, or can fracture more easily. Bone fractures often occur from falling or other common accidents. Spine fractures can occur while doing daily activities without any trauma. Other bone diseases include Paget's disease and osteogenesis imperfecta. Paget's disease causes skeletal deformities and fractures. A healthy skeletal system with strong bones is essential to overall health and quality of life. Strong bones support us and are the framework for our muscles. Bones are a storehouse for vital minerals needed to live. Strong bones protect the heart, lungs, brain, and other organs from injury. Weak bones often result in painful and debilitating fractures. Hip fractures are the most devastating type of bone fracture and account for almost 300,000 hospitalizations each year.

Joint is juncture between two bones. Some joints are immovable, e.g., those that connect the bones of the skull, which are separated merely by short, tough fibers of cartilage. Movable joints are found for the most part in the limbs. Hinge joints provide a forward and backward motion, as at the elbow and knee. Pivot joints permit rotary movement, like the turning of the head from side to side. Ball-and-socket joints, like those at the hip and shoulder, allow the greatest range of movement, as the rounded end of one bone fits into the hollow or socket of another bone, separated by elastic cartilage. Joints can further be classified as fibrous, cartilaginous, and synovial. Collagen fibers connect fibrous joints. Synovial joints ease movement through the use of a lubricating liquid, supplied by the synovial membrane that lines movable joints. In synovial joints, a cushioning sac known as a bursa contains the fluid, which lubricates and nourishes the joint. Those joints which lack synovial fluid are nourished by blood. Holding the joints in place are strong ligaments fastened to the bones above and below the joint. Joints are subject to sprains and dislocations, as well as to infections and disorders caused by such diseases as arthritis. In recent years, the use of artificial joints has become increasingly common, particularly in hip and knee replacement. Many orthopedic surgeons now perform operations of this sort, using metal or plastic replacement joints in order to relieve pain, or to prevent or correct joint deformity.

Arthritis is a joint disorder featuring inflammation. A joint is an area of the body where two different bones meet. A joint functions to move the body parts connected by its bones. Arthritis literally means inflammation of one or more joints. Arthritic diseases include rheumatoid arthritis and psoriatic arthritis, which are autoimmune diseases; septic arthritis, caused by joint infection; and the more common osteoarthritis, or degenerative joint disease. Arthritis can be caused from strains and injuries caused by repetitive motion, sports, overexertion, and falls. Arthritic joints can be sensitive to weather changes. The increased sensitivity is thought to be caused by the affected joints developing extra nerve endings in an attempt to protect the joint from further damage.

Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle." Muscles serve many functions. They produce movements of the body. They are used to maintain position of the body against gravity. They also can be used to alter pressures or tensions of structures within the body as well as protect the body. The three types or classifications of muscle are striated (skeletal), smooth and cardiac. Striated muscles attach to the skeleton. Smooth muscle is the type such as found in the stomach and blood vessels. Cardiac muscle forms the walls of the heart. Muscle is composed of muscle cells (sometimes known as "muscle fibers"). Within the cells are myofibrils; myofibrils contain sarcomeres, which are composed of actin and myosin. Individual muscle cells are lined with endomysium. Muscle cells are bound together by perimysium into bundles called fascicules; the bundles are then grouped together to form muscle, which is lined by epimysium. Muscle spindles are distributed throughout the muscles and provide sensory information to the central nervous system.


Common bone, joint, and muscle disorders

Osteoporosis - Osteoporosis is a disease of bone in which the amount of bone is decreased and the strength of trabecular bone is reduced, cortical bone becomes thin and bones are susceptible to fracture. Osteoporosis is condition that features loss of the normal density of bone. Osteoporosis leads to literally abnormally porous bone that is more compressible like a sponge than dense like a brick. This disorder of the skeleton weakens the bone leading to an increase in the risk of breaking bones (bone fracture).
Arthritis - Arthritis is a group of conditions that affect the health of the bone joints in the body. Arthritic diseases include rheumatoid arthritis and psoriatic arthritis, which are autoimmune diseases; septic arthritis, caused by joint infection; and the more common osteoarthritis, or degenerative joint disease. Arthritis can be caused from strains and injuries caused by repetitive motion, sports, overexertion, and falls. Unlike the autoimmune diseases, osteoarthritis largely affects older people and results from the degeneration of joint cartilage.
Plantar fasciitis - Plantar fasciitis is an inflammation (irritation and swelling with presence of extra immune cells) of the thick tissue on the bottom of the foot that causes heel pain and disability. The plantar fascia is a very thick band of tissue that covers the bones on the bottom of the foot. This fascia can become inflamed and painful in some people, making walking more difficult. The disorder is common in runners and in dancers and may occur in people whose occupations involve standing for prolonged periods. A change in shoe style can also lead to plantar fasciitis.
Fibromyalgia - Fibromyalgia is a debilitating chronic illness characterized by diffuse pain, fatigue, and a wide range of other symptoms. It is a syndrome, not a disease. It is not contagious, and is probably genetic. The nature of fibromyalgia is not well understood. Fibromyalgia is sometimes categorized as primary or secondary. In primary fibromyalgia (also called idiopathic fibromyalgia) the causes are not known, and in secondary fibromyalgia the causes can be identified. Primary fibromyalgia is the more common form.
Muscular dystrophy - Muscular dystrophy (MD) is a broad term that describes a genetic (inherited) disorder of the muscles. Muscular dystrophy causes the muscles in the body to become very weak. The muscles break down and are replaced with fatty deposits over time. Defective genes are the cause of muscular dystrophy. The specific gene disorder is known for most of the common muscular dystrophies, but there are many less common conditions for which the specific defects need to be discovered. A family history of the condition is often but not always present.
Bone, joint, & muscle disorders

Topics in bone, joint, and muscle disorders

Bone diseases
Bone tumors
Bone cancer
Muscle diseases
Spine (neck and back) disorders
Dupuytren's contracture
Plantar fasciitis
Rheumatoid arthritis
Juvenile rheumatoid arthritis
Septic arthritis (infectious Arthritis)
Psoriatic arthritis
Reiter's syndrome (reactive arthritis)
Ankylosing spondylitis
Gout (gouty arthritis)

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