Overview
This lecture introduces the anatomy, functions, terminology, common diseases, diagnostics, and related medical professions of the muscular system.
Anatomy of the Muscular System
- The body has over 600 muscles, which significantly contribute to body weight.
- There are three muscle tissue types: skeletal, cardiac, and smooth.
- Muscle fibers are specialized cells that make up muscle tissue.
- Fascia is fibrous connective tissue that encloses muscles.
Types of Muscle Tissue
- Skeletal muscle is voluntary, striated, and moves the skeleton.
- Cardiac muscle is found only in the heart, is striated, and has intercalated discs for coordinated contraction.
- Smooth muscle is involuntary, non-striated, and found in internal organs and blood vessels.
Functions of the Muscular System
- The main function is to assist with movement by contracting and relaxing muscle fibers.
- Muscles maintain posture and stabilize joints.
- Muscles generate heat to help maintain homeostasis.
Muscle Actions and Movements
- Flexion: decreases angle between bones; extension: increases angle.
- Abduction: moves limb away from the midline; adduction: moves it toward the midline.
- Rotation: circular movement around an axis.
- Dorsiflexion: moves foot upward; plantar flexion: points foot downward.
- Supination: palms up; pronation: palms down.
Muscle Naming Conventions
- Muscles may be named by divisions (biceps, triceps), size (maximus, minimus), shape (deltoid), or action (flexor, adductor).
Diseases, Disorders, and Procedures
- Muscular dystrophy: inherited disease causing muscle weakness.
- Cerebral palsy: brain development disorder affecting muscle control.
- Carpal tunnel syndrome: median nerve compression causing hand pain and numbness.
- Paralysis: loss of muscle strength/control; types include paresis, paraplegia, quadriplegia, hemiplegia.
- Sprain: ligament injury at a joint; Strain: tendon or muscle injury.
- Electromyography (EMG): tests nerve and muscle function.
- MRI: imaging test to diagnose muscular disorders.
- Range of motion testing: determines movement in a joint.
Medical Professions Involved
- Orthopedic surgeons: treat disorders of the musculoskeletal system.
- Neurologists: diagnose and treat disorders of the nervous system and muscles.
- Kinesiologists: focus on biomechanics, pain management, and injury prevention.
- Occupational therapists: help patients regain skills for daily living.
- Certified occupational therapist assistants: support occupational therapy treatments.
- Physical therapists: help patients maximize mobility and rehabilitate injuries.
- Physical therapist assistants: assist with therapy treatments and plans.
Key Terms & Definitions
- Skeletal muscle — voluntary, striated muscle responsible for moving bones.
- Cardiac muscle — heart muscle (myocardium), striated, pumps blood.
- Smooth muscle — involuntary, non-striated muscle in organs/vessels.
- Fascia — connective tissue surrounding muscles.
- Excitability — ability of muscle fibers to respond to stimulation.
- Antagonistic — muscles acting in opposition.
- Flexion/Extension — bending/straightening of joints.
- Abduction/Adduction — limb movement away/toward body midline.
- EMG — test recording muscle electrical activity.
- MRI — imaging technique using magnetic fields/radio waves.
Action Items / Next Steps
- Review muscle types, locations, and functions.
- Memorize definitions of key terms and common muscle actions.
- Study common muscle disorders and diagnostic tests.
- Watch suggested videos for visual understanding of muscle anatomy and movement.
- Complete any assigned practice or self-tests.