Exam 16 - Introduction to the Msk

Musculoskeletal System Overview

• The musculoskeletal system is crucial for daily physical function, movement, and manipulation of objects. It encompasses bones, joints, and soft tissues.

Skeletal System Functions

• Support: Provides a framework for internal tissues and organs.
• Protection: Forms a protective cage around vital organs (e.g., cranium protects the brain, vertebrae protect the spinal cord).
• Movement: Skeletal muscles attached to bones provide leverage for movement via muscle contraction and bone pulling.
• Mineral Storage: Stores minerals like calcium and phosphorus, releasing them when needed by the body.
• Hematopoiesis: Blood cell formation occurs in bone marrow.

Skeletal System Structures

• Bones: There are 206 in the human skeleton. Classified by shape: long (extremities), short (hands/feet), flat (skull/sternum), irregular (vertebrae).
• Joints: Points of contact between bones, enabling movement and holding the skeleton together. Three types: synarthrosis (immovable), amphiarthrosis (slightly movable), diarthrosis (freely movable).
• Muscles: Essential for movement, posture maintenance, and heat production. 85% of body heat comes from muscle contraction. Controlled voluntarily or involuntarily.

Muscle Structure and Function

• Muscle Structure: Hundreds of muscle fibers bundled together, surrounded by connective tissue (epimysium).
• Tendons: Connect muscles to bones, transmitting force during contraction.
• Tendon Sheaths: Found in ankle and wrist, contain synovial fluid enabling smooth tendon movement and keeping tendons in place.

Nerve and Blood Supply to Muscles

• Oxygen and Nutrition: Muscles require a constant supply for function.
• Blood Vessels: Deliver oxygen and nutrients, remove waste products during metabolism.
• Nerve Cells: Send impulses to stimulate muscle cells at the neuromuscular junction, triggering contraction.
• Neuromuscular Junction: The contact point between nerve and muscle fibers.
• Neurotransmitter: Acetylcholine is the neurotransmitter for skeletal muscle contraction.
• Cholinesterase: Breaks down acetylcholine to allow muscle relaxation between impulses.

Muscle Contraction

• All-or-None Principle: Muscle fibers contract completely when adequately stimulated or completely don't when not appropriately stimulated.
• Graded Response: The force of muscle contraction depends on the number of muscle cells activated.
• Muscle Tone: Constant readiness of skeletal muscles, maintaining posture through alternating contraction/relaxation of muscle fibers. In paralysis, lack of response leads to no movement.

Types of Body Movements

• Flexion: Decreases the angle between bones.
• Extension: Increases the angle between bones.
• Abduction: Movement away from the body's midline.
• Adduction: Movement toward the body's midline.
• Rotation: Movement around a bone's longitudinal axis.
• Supination: Palm faces upward.
• Pronation: Palm faces downward.
• Dorsiflexion: Foot top elevates.
• Plantar Flexion: Foot bottom directs downward.

Muscle Groups (Axial vs. Appendicular)

• Axial: Head, face, neck, trunk.
• Appendicular: Extremities.

Diagnostic Tests (Musculoskeletal)

• X-Ray: Detects fluid, joint irregularities, and fractures. Pregnant women must be screened before examination due to possible harm to the fetus.
• Myelogram: Injects radiopaque dye into the lumbar spine to visualize herniated disks. Semi-Fowler's position for 8 hours to keep dye in place. Important to encourage hydration for faster dye absorption.
• MRI: Uses magnetism & radio waves to create cross-sectional images of bone, joints, and soft tissues. Remove metal before the exam.
• CT Scan: Uses x-ray beams to create 3-D images of body sections. Fasting required (3-4 hours)
• Bone Scan: Detects metastatic and inflammatory bone disease using radionuclides. No food/fluid restrictions after administration but hydration encouraged.
• Endoscopic Exam (Arthroscopy): Visualizes joint interiors through a lighted tube. Surgical procedure.
• Aspiration: Collects body fluid samples using local anesthetic and sterile technique. Rest, elevation, and ice after procedure.
• Electromyogram (EMG): Measures electrical activity in skeletal muscles using inserted needle electrodes.

Laboratory Tests (Musculoskeletal)

• Calcium: Normal range 9-10.5 mg/dL; Increased levels can point to bone tumors, renal failure, etc.
• Erythrocyte Sedimentation Rate (ESR): Nonspecific inflammatory marker; elevated in rheumatoid arthritis, infections, etc. Normal ranges vary by gender.
• Lupus Erythematosus (LE): Test for lupus; no LE seen is normal.
• Rheumatoid Factor: Test for rheumatoid arthritis and lupus; normal ranges vary.
• Uric Acid: Normal ranges vary by gender; elevated levels are linked to Gout, some kidney issues, and certain cancers.

Explore the musculoskeletal system's essential roles in human movement and support. This quiz covers functions, structures, and classifications of bones, joints, and soft tissues. Test your knowledge on topics like mineral storage and hematopoiesis.