Muscular System
- Introduction
• The muscular system is made up of muscles and tendons that enable movement, stability, and posture.
• It also plays vital roles in circulation, respiration, digestion, heat production, and body functions.
• Three types of muscles exist: skeletal, smooth, and cardiac, each with distinct structure and function. - Types of Muscles
A. Skeletal Muscle
• Voluntary muscle attached to bones by tendons.
• Responsible for body movement, posture, and joint stabilization.
• Striated (striped) appearance under a microscope.
• Produces heat during contraction (helps maintain body temperature).
• Examples: biceps brachii, quadriceps femoris.
B. Smooth Muscle
• Involuntary muscle found in walls of internal organs (stomach, intestines, blood vessels).
• Controls movements like food passage, blood flow, and urine flow.
• Non-striated and controlled by autonomic nervous system.
• Enables functions like digestion, blood pressure regulation.
C. Cardiac Muscle
• Involuntary, striated muscle found only in the heart.
• Responsible for heart contractions pumping blood.
• Has its own pacemaker for rhythmic contractions.
• Strong and resistant to fatigue. - Anatomy of Skeletal Muscle
• Composed of bundles of muscle fibers (cells).
• Each fiber contains myofibrils made of actin and myosin filaments enabling contraction.
• Covered by connective tissue layers: endomysium, perimysium, and epimysium.
• Attached to bones via tendons.
• Muscles work in antagonistic pairs (e.g., biceps and triceps). - Functions of the Muscular System
A. Movement
• Skeletal muscles contract to move bones at joints.
• Enables gross movements (walking, running) and fine movements (writing, facial expressions).
B. Posture Maintenance
• Constant muscle activity keeps the body upright and balanced.
• Core muscles stabilize the spine and pelvis.
C. Joint Stabilization
• Muscles and tendons stabilize joints during movement.
D. Heat Production
• Muscle contractions generate heat, important for maintaining body temperature.
E. Circulation Support
• Cardiac muscle pumps blood.
• Smooth muscles regulate blood vessel diameter influencing blood pressure.
F. Respiration
• Diaphragm and intercostal muscles control breathing.
G. Digestive and Urinary Functions
• Smooth muscles move food through GI tract and control bladder emptying. - Muscle Contraction Mechanism (Basic)
• Triggered by nerve impulse leading to calcium release.
• Actin and myosin filaments slide past each other.
• Energy from ATP powers contraction.
• Relaxation occurs when impulses stop and calcium is reabsorbed. - Common Disorders of the Muscular System
• Muscle strain and sprain
• Muscular dystrophy (genetic muscle degeneration)
• Myasthenia gravis (autoimmune causing muscle weakness)
• Tendonitis (inflammation of tendons)
• Cramps and spasms
• Fibromyalgia (chronic muscle pain disorder) - Nursing Care and Considerations
• Assist in muscle strengthening and rehabilitation exercises.
• Monitor for signs of muscle weakness or pain.
• Educate patients on proper body mechanics to prevent injuries.
• Support patients with chronic muscle diseases.
• Encourage adequate nutrition for muscle health (protein, vitamins).
• Administer medications as prescribed for muscular disorders. - Summary for Quick Review
The muscular system includes skeletal, smooth, and cardiac muscles, each enabling essential body functions. Skeletal muscles allow voluntary movement and posture; smooth muscles control involuntary motions in organs, and cardiac muscle pumps blood. Muscles contract via sliding filaments powered by ATP. The system supports movement, stability, heat generation, and vital functions like circulation and digestion. Nursing care focuses on monitoring muscle health, preventing injury, and supporting rehabilitation.