Musculoskeletal system

CFCF / CC BY-SA

Working together to provide support and produce movement, the structures of the musculoskeletal system include:
• muscles
• bones
• cartilage
• joints, bursae, tendons, and ligaments.

Muscles
There are three major muscle types:
• skeletal muscles (voluntary, striated muscles)
• smooth (involuntary muscles)
• cardiac (involuntary, striated muscles).

Bones• 206 in the human body
• Classified by shape and location
• Perform mechanical and physiologic functions
• Begin as cartilage
• Formed by process called endochondral ossification
• Continuously torn down and rebuilt by osteoclasts and osteoblasts

Cartilage
• Dense connective tissue consisting of fibers embedded in a strong, gel-like substance
• Avascular and not innervated
• Supports, cushions, and shapes body structures
• May be fibrous, hyaline, or elastic

Joints
• The union of two or more bones
• Classified by how much movement they allow; synarthrosis, no movement; amphiarthrosis, slight movement; diarthrosis, free movement
• Supporting the joints are the:
–bursae — cushions located at friction points around joints and between tendons, ligaments, and bones
–tendons — bands of fibrous connective tissue that attach muscle to bone to stabilize joints
–ligaments — bands of fibrous connective tissue that tie bones to other bones to stabilize joints.

How musculoskeletal disorders develop
• Carpal tunnel syndrome — caused by inflammation or fibrosis of tendon sheath that results in median nerve compressed by edema.
• Gout — caused by decreased uric acid excretion by the kidneys resulting in painful swelling and tenderness caused by rising urate levels.
• Osteoarthritis — caused by deterioration of joint cartilage that results in reactive new bone forming in the joints.
• Osteoporosis — caused by reduction in bone matrix and bone remineralization that results in bones becoming soft and easily fractured.