Musculoskeletal System Overview and Joints Types

Musculoskeletal System Overview

• The musculoskeletal system comprises bones, joints, cartilage, ligaments, tendons, and muscles.
• Bone cells include osteoblasts (bone growth), osteocytes (mineral regulation), and osteoclasts (mineral release).
• The human skeleton has 206 bones, categorized as long, short, flat, or irregular.
• Bones have internal structures—compact and spongy (containing red bone marrow)—and haversian systems (bone canals).
• Joints are articulation points between bones, categorized as immovable, slightly movable, or freely movable.
• Ligaments connect bones, tendons connect muscles to bones, and cartilage acts as a cushion.
• Bursae are fluid-filled sacs cushioning friction points.

Types of Joints

• Hinge: Bidirectional movement (flexion/extension), e.g., elbow.
• Pivot: Rotational movement, e.g., head/neck.
• Saddle: Circular movement, e.g., thumb.
• Ball and socket: Wide range of movement (rotation, flexion/extension), e.g., shoulder/hip.
• Condyloid: Up-down and side-to-side movement, e.g., head/neck.
• Gliding: Lateral, up/down movement, e.g., vertebrae.

Muscle Structure and Function

• Skeletal muscles are bundles of fibers, enveloped by fascia (connective tissue).
• Muscles have properties for contraction, extension, stretching, and elasticity, fueled by electrical excitation.
• Muscles are attached to bones via tendons.
• Muscle groups, through opposing contractions, enable joint movement.

Bone Functions

• Bones provide shape and support for internal organs.
• Bones protect internal organs.
• Bones provide attachment points for tendons and ligaments for movement.
• Red bone marrow forms blood cells.
• Bones store and release calcium and phosphorus.
• Blood/lymph vessels transport nutrients and remove waste.
• Bone remodeling is a continuous process.

Aging and the Musculoskeletal System

• Ossification (cartilage to bone) is complete by ~25 years old.
• Bone density decreases with age, more pronounced in women (osteoporosis).
• Older bones are brittle, increasing fracture risk.
• Healing from fractures is slower.
• Kyphosis (dowager's hump) develops due to intervertebral cartilage thinning.
• Joint cartilage erodes, leading to stiffness, crepitation, and reduced mobility.
• Ligaments calcify and lose elasticity.
• Muscle mass and strength decline due to cell loss and atrophy.
• Tendons shrink, slowing muscle movements.
• Muscle cramps, especially nocturnal, increase.

Musculoskeletal Disorders

• Causes include disease, trauma, malnutrition, and aging.
• Trauma can cause bruising, strains, sprains, and fractures.
• Poor nutrition (lack of calcium, phosphorus, protein) can weaken bones and muscles.
• Tumors (primary or metastatic) can affect bone health.
• Estrogen loss after menopause contributes to osteoporosis.

Musculoskeletal Disorder Prevention

• Maintain mobility and motion.
• Weight-bearing exercise is vital for bone health, muscle strength, and balance.
• Correct lifting techniques prevent strain/sprains.
• Safety measures (seatbelts, helmets) prevent trauma.
• Appropriate calcium, vitamin D, and protein intake are critical.
• Avoid long-term steroid use.

Complementary Therapies

• Tai Chi benefits balance and cognitive function, reduces falls (e.g., in older adults).

Nutrition and Bone Health

• Adequate calcium and phosphorus are crucial for bone growth/density.
• Dairy and some non-dairy foods are good calcium sources (salmon, sardines, tofu).
• Magnesium and vitamin K are also necessary for healthy bones.

Smoking and Musculoskeletal Health

• Smoking increases osteoporosis risk, hip fracture risk, exercise-related injuries, and impacts fracture/wound healing.
• Smoking negatively affects athletic performance and is linked to low back pain and rheumatoid arthritis.

Diagnostic Tests

• Laboratory tests diagnose bone disorders (calcium, phosphorus, alkaline phosphatase, CPK, uric acid).
• Bone scans, dual-energy x-ray absorptiometry (DEXA) scans, arthrocentesis, and electromyography are specific diagnostic tests.

Range of Motion Testing

• Active ROM tests involve patient movement.
• Passive ROM tests involve examiner movement.
• Goniometry measures joint movement(s).
• Muscle strength is graded from 0 (paralysis) to 5 (normal).
• Other methods of assessment include inspection, palpation, and joint stress testing.

Nursing Management

• Patient history should consider disorders affecting other body systems that might affect bones and muscles (ex: sickle cell disease).
• Relevant factors like nutritional deficiencies are also to be considered.