The Musculoskeletal System

• The body's bones, muscles, and joints make up the musculoskeletal system.
• The nervous system controls and innervates the musculoskeletal system.
• The musculoskeletal system provides structure and movement for body parts.

Bones

• Bones provide structure, protection, act as levers, store calcium, and produce blood cells.
• The human body has 206 bones.
• The axial skeleton includes the head and trunk.
• The appendicular skeleton includes the extremities, shoulders, and hips.
• Bones consist of osseous tissue.
• Compact bone is hard and dense, forming the shaft and outer layers of bones.
• Spongy bone contains spaces and makes up the ends and centers of bones.
• Osteoblasts are active cells that form bone tissue.
• Osteoclasts are cells that degrade bone tissue.
• Red marrow produces blood cells
• Yellow marrow consists mostly of fat.
• The periosteum covers bones and contains osteoblasts and blood vessels for nourishment and new bone tissue formation.
• Bones have various shapes, including short (carpals), long (humerus, femur), flat (sternum, ribs), and irregular (hips, vertebrae) bones.

Skeletal Muscles

• The body consists of skeletal, smooth, and cardiac muscles.
• The musculoskeletal system includes 650 skeletal (voluntary) muscles under conscious control.
• Skeletal muscles consist of long muscle fibers (fasciculi) arranged in bundles and joined by connective tissue.
• Tendons are strong, fibrous cords that attach skeletal muscles to bones.
• Skeletal muscles assist with posture, produce body heat, and enable movement.
• Abduction involves moving away from the midline of the body.
• Adduction involves moving toward the midline of the body.