Chapter 4 PowerPointComprehensive Study Notes on the Muscular System

Functions of the Muscular System

• Body Posture and Movement: Muscles hold the human body erect and make all physical movement possible.
• Heat Generation: Muscle movement generates nearly $85\%$ of the heat that keeps the body warm.
• Digestive Movement: Muscle contractions move food and waste products through the digestive system.
• Circulatory Assistance: Muscle movements, such as walking, actively aid the flow of blood through veins as it returns to the heart.
• Fluid Transportation: Muscle action moves various fluids through the specialized ducts and tubes associated with other body systems.

Structures of the Muscular System

• Musculoskeletal System:
  • Refers to the combined functional unit of the muscular and skeletal systems.
  • Provides the body with form, structural support, stability, and the ability to move.
  • The human body contains more than $600$ individual muscles.
• Muscle Fibers:
  • Long, slender cells that constitute the structural units of muscles.
  • Muscles consist of groups of these fibers bound tightly together by connective tissue.
• Fascia:
  • A band of connective tissue that envelops, separates, or binds together muscles or groups of muscles.
  • Flexible and pliable to allow smooth muscle movements.
  • Myofascial: Pertaining to muscle tissue and fascia.
• Tendons:
  • Narrow, highly organized bands of nonelastic, dense, fibrous connective tissue.
  • Function specifically to attach muscle to bone.
  • Patellar Tendon: Attaches muscles to the bottom of the patella (kneecap).
  • Achilles Tendon: Attaches the gastrocnemius muscle (the major muscle of the calf) directly to the heel bone.
  • Functional Distinction: Tendons attach muscle to bone, whereas ligaments join bone to bone.

Types of Muscle Tissue

• Skeletal Muscle:
  • Attached directly or indirectly to the bones of the skeleton.
  • Makes voluntary body motions possible.
  • Classified as voluntary, striated muscle tissue due to its distinct cross-stripes under microscopic view and conscious control.
• Smooth Muscle:
  • Located in the walls of internal organs, blood vessels, and ducts.
  • Classified as involuntary, unstriated, visceral muscle tissue because it lacks cross-stripes and operates without conscious control.
• Myocardial Muscle:
  • Forms the muscular walls of the heart and is also known as the myocardium or cardiac muscle.
  • Undergoes continuous, rhythmic contraction and relaxation to pump blood throughout the body.
  • Histologically resembles striated skeletal muscle in appearance, but acts involuntarily like smooth muscle.

Contrasting Muscle Motions

• Abduction and Adduction:
  • Abduction: Movement of a limb (arm or leg) away from the midline of the body. An abductor is a muscle that performs this motion.
  • Adduction: Movement of a limb (arm or leg) toward the midline of the body. An adductor is a muscle that performs this motion.

• Flexion and Extension:
  • Flexion: Decreasing the angle between two bones by bending a limb at a joint. A flexor muscle decreases this angle.
  • Extension: Increasing the angle between two bones by straightening out a limb. An extensor muscle increases this angle.
  • Hyperextension: The extreme or overextension of a limb or body part beyond its normal anatomical movement limit.

• Supination and Pronation:
  • Supination: The act of rotating the arm or leg so that the palm of the hand or sole of the foot is turned forward or upward (resembling holding a bowl of soup).
  • Pronation: The act of rotating the arm or leg so that the palm of the hand or sole of the foot is turned downward or backward.

Medical Specialties Related to the Muscular System

• Neurologist: A physician who specializes in diagnosing and treating the causes of paralysis and other complex neuromuscular and muscular disorders.
• Occupational Therapist (OT): A healthcare provider who helps enable patients to participate in necessary activities of daily living (ADL) through customized therapeutic adaptations and training.
• Physical Therapist (PT): A clinician who provides treatment to prevent disability or restore physical function through therapeutic exercise, heat, massage, and other techniques.
• Sports Medicine Physician: A medical specialist focused on the prevention, diagnosis, and treatment of injuries to bones, joints, and muscles in athletes and active individuals.

Pathology of the Muscular System

Fibers, Fascia, and Tendons

• Fasciitis: Inflammation of a fascia.
• Fibromyalgia: A debilitating chronic condition characterized by widespread fatigue, diffuse or specific muscle, joint, or bone pain, and a broad range of related systemic symptoms.
• Tenosynovitis: Inflammation of the protective sheath that surrounds a tendon.
• Tendinitis: Acute inflammation or irritation of tendons caused by excessive or unusual joint use.
• Tendinosis: A chronic tendon condition characterized by persistent pain, caused by repetitive overuse or an injury that has failed to heal properly.
• Chronic Fatigue Syndrome (CFS): A complex and debilitating disorder of unknown etiology that affects multiple body systems simultaneously.

Muscle Disorders

• Adhesion: A band of fibrous tissue that abnormally holds internal structures together; can form in muscles or internal organs as a result of an injury or surgical procedure.
• Atrophy: Weakness, wasting away, or decrease in size of body tissues and structures; caused by underlying pathology or prolonged disuse of the muscle.
• Cachexia: A state of severe physical wasting away due to significant loss of weight and muscle mass; occurs in patients with advanced chronic diseases such as cancer or AIDS.
• Hernia: The protrusion of a tissue or organ through a structural weakness in the surrounding muscle wall that normally contains it.
  • Inguinal Hernia: The protrusion of abdominal-cavity contents through the inguinal canal in the groin; represents the most common type of hernia.
• Myalgia: Tenderness or pain in one or more muscles.
• Polymyositis: Simultaneous inflammation and progressive weakening of voluntary muscles in multiple body parts.
• Rhabdomyolysis: The breakdown and death of muscle fibers resulting in the release of toxic cellular contents into the bloodstream, which can lead to severe medical complications such as acute renal failure.
• Sarcopenia: The progressive loss of muscle mass, strength, and functional capacity associated with aging.

Disorders of Muscle Movement

• Ataxia: The lack of muscle coordination during voluntary movement, leading to shaky, unsteady, and clumsy movements.
• Contracture: The permanent tightening of fascia, muscles, tendons, ligaments, or skin that occurs when normally elastic connective tissues are replaced by nonelastic fibrous tissue.
• Intermittent Claudication (IC): Pain in the leg muscles during exercise caused by poor circulation, which is characteristically relieved by brief rest.
• Spasm: A sudden, involuntary contraction of one or more muscles.
  • Tic: A spasmodic, repeated involuntary muscle twitching, frequently involving the eyelids or facial muscles.

Systemic Neuromuscular and Genetic Diseases

• Myasthenia Gravis: A chronic autoimmune neuromuscular disease that damages the neuromuscular junction, leading to muscle weakness.
• Muscular Dystrophy (MD): A general term for a group of more than $30$ genetic diseases characterized by progressive weakness and degeneration of skeletal muscles without affecting the nervous system.
  • Duchenne Muscular Dystrophy (DMD): The most common severe form of muscular dystrophy.
  • Becker Muscular Dystrophy (BMD): A less severe, slower-progressing form of muscular dystrophy.

Repetitive Stress Disorders

• Compartment Syndrome: Compression of nerves and blood vessels caused by swelling within a closed fascial compartment that separates groups of muscles in the arm or leg.
• Overuse Injuries: Minor tissue injuries that recur because they have not been granted adequate time to heal.
• Overuse Tendinitis: Inflammation of tendons resulting from repeated, excessive, or unaccustomed joint motion.
• Trigger Finger: A painful and progressive restriction of finger movement caused by inflammation of a tendon's synovial sheath.
• Carpal Tunnel Syndrome: Occurs when tendons passing through the narrow carpal tunnel of the wrist become chronically overused, inflamed, and swollen, creating pressure against the median nerve.
  • Carpal Tunnel Release: A surgical procedure performed to relieve pressure on the median nerve by cutting the carpal ligament.

• Ganglion Cyst: A benign, fluid-filled swelling that usually develops on the outer surface of a tendon sheath or joint capsule in the wrist or hand; typically painless and requires no treatment unless symptomatic.
• Ankle and Foot Pathology:
  • Heel Spur: A calcium deposit in the plantar fascia near its attachment to the calcaneus (heel bone).
  • Plantar Fasciitis: Inflammation of the thick band of tissue (plantar fascia) that runs across the bottom of the foot, connecting the heel bone to the toes.

Sports Injuries

• Soft Tissue Injury: Damage to structures such as skin, muscles, ligaments, and tendons (including contusions, sprains, and strains).
• Sprain: An injury to a joint involving a stretched, wrenched, or torn ligament.
• Strain: An injury to a muscle or the attachment of a tendon involving stretching or tearing of tissue.
• Shin Splint: Pain caused by the tibialis anterior muscle tearing away from its attachment along the shin bone (tibia).
• Hamstring Injury: A strain or tear occurring in the posterior thigh muscles, caused by violent muscle contraction during activity.
• Achilles Tendinitis: Painful inflammation of the Achilles tendon caused by repetitive stress or trauma.

Spinal Cord Injuries (SCI) and Paralysis

• Mechanism: Damage occurs when a fractured piece of vertebra presses directly into the spinal cord, or when vertebrae are displaced out of alignment, leading to partial or complete loss of neural communication between the brain and areas below the lesion.
• Determining Factors: The specific type and severity of paralysis are dictated by the specific vertebral level closest to the injury site.
• Incomplete Injury: Partial retention of neurological, motor, or sensory function below the level of the injury.
• Complete Injury: Complete absence of sensation and voluntary motor control below the level of the lesion (does not rule out potential long-term functional adaptation).
• Classifications of Paralysis:
  • Myoparesis: Weakness or partial paralysis of a muscle.
  • Hemiparesis: Slight weakness or partial paralysis affecting only one side of the body; commonly results from a cerebrovascular accident (stroke).
  • Hemiplegia: Total paralysis affecting one lateral half of the body.
  • Paraplegia: Paralysis of both lower extremities and the trunk below the level of injury.
  • Quadriplegia (Tetraplegia): Total paralysis involving all four extremities and the torso.

Diagnostic Procedures of the Muscular System

• Deep Tendon Reflexes (DTR): Assessment of involuntary motor responses to a mechanical stimulus, performed using a rubber reflex hammer to tap a specific tendon (such as testing the patellar knee-jerk reflex).

• Range-of-Motion Testing (ROM): A diagnostic procedure used to evaluate joint flexibility, degree of movement, and surrounding muscle strength.
• Electromyography (EMG): A diagnostic test that measures and records the electrical activity generated within muscle fibers during contraction and at rest.
• Muscle Biopsy: The removal of a small plug or sample of muscle tissue for microscopic and histopathological examination.

Treatment Procedures of the Muscular System

Therapeutic Techniques

• Myofascial Release: A specialized soft-tissue manipulation technique that involves applying gentle, sustained pressure to ease pain and restriction in tight fascial structures.
• Occupational Therapy (OT): Rehabilitation focused on assisting individuals with physical or cognitive impairments to perform essential activities of daily living (ADL).
• Physical Therapy (PT): Comprehensive rehabilitation aimed at restoring physical movement, preventing permanent disability, and improving physical functional capacity using targeted exercise, physical agents, heat, and massage.
• Transcutaneous Electrical Nerve Stimulation (TENS): A therapeutic device that delivers controlled electrical pulses through electrodes placed on the skin to alter pain perception and muscle responses.
• RICE Protocol: The standard immediate first aid intervention for acute soft tissue injuries:
  • Rest
  • Ice
  • Compression
  • Elevation

Surgical Procedures

• Tendon Interventions:
  • Tenodesis: The surgical suturing and anchoring of the end of a tendon directly to a bone.
  • Tenolysis: The surgical release of a tendon from surrounding restrictive adhesions.
  • Tenotomy: The surgical cutting or division of a tendon to relieve a contracture or allow structural lengthening.
• Muscle Interventions:
  • Myorrhaphy: Surgical suturing of a divided or torn muscle.
  • Myotomy: Surgical incision directly into a muscle body.

Word Parts and Vocabulary

Word Parts

• a-: without, lack of
• ab-: away from
• ad-: toward
• -al: pertaining to
• anti-: against
• -ar: pertaining to
• -asthenia: weakness, lack of strength
• bi-: two
• brady-: slow
• cardi/o: heart
• -cele: hernia, swelling, tumor
• -ceps: head
• cleid/o: clavicle (collar bone)
• clon/o: rapid switching between contraction and relaxation
• condyl/o: condyle, knuckle
• cutane-: skin
• -desis: surgical fixation, binding together
• duct-: lead, carry
• dys-: bad, difficult, painful
• electr/o: electricity
• epi-: upon, on, over
• ex-: out of, away from
• fasci/o: fascia
• fibr/o: fiber
• flex-: bend
• -graphy: process of recording
• hemi-: half
• herni/o: hernia
• hyper-: excessive, increased
• hypo-: deficient, decreased
• -ia: abnormal state, condition
• -ic: pertaining to
• -ion: action, process
• -itis: inflammation
• kines/o, kinesi/o: movement, motion
• -lysis: breakdown, separation, setting free
• my/o, muscul/o, myos/o: muscle
• -necrosis: tissue death
• neur/o: nerve
• -oma: tumor, mass
• -osis: abnormal condition or disease
• -otomy: surgical incision
• -paresis: partial paralysis, weakness
• -pathy: disease, emotion
• -penia: deficiency, lack of
• -plegia: paralysis, stroke
• poly-: many
• quadr/i: four
• rhabdomy/o: striated muscle
• -rrhaphy: surgical suturing
• -rrhexis: rupture
• sarc/o: flesh, connective tissue
• sphincter/o: sphincter, tight band
• stern/o: sternum (breastbone)
• synov/o: synovial membrane, synovial fluid
• tax/o: coordination, order
• ten/o, tend/o, tendin/o: tendon
• ton/o: tone, tension, stretching
• trans-: across, through
• tri-: three
• -trophy: nourishment, growth

Core Medical Terms

• Achilles Tendon: Major tendon connecting the calf muscle to the heel.
• Adhesion: Fibrous tissue band holding structures together abnormally.
• Ataxia: Inability to coordinate voluntary muscle movements.
• Atrophy: Muscle wasting or loss of tissue mass.
• Cachexia: Severe physical wasting due to chronic severe illness.
• Carpal Tunnel Syndrome: Compression of the median nerve within the wrist.
• Compartment Syndrome: Pressure accumulation within a closed fascial muscle space.
• Contracture: Permanent fibrotic shortening of muscle or fascia.
• Electromyography: Recording of skeletal muscle electrical activity.
• Fascia: Sheet of fibrous tissue surrounding muscles and organs.
• Hemiplegia: Complete paralysis of one side of the body.
• Involuntary Muscle: Muscle functioning automatically without conscious control.
• Ligament: Fibrous tissue connecting bone to bone.
• Muscle: Tissue capable of contracting to produce movement.
• Occupational Therapist: Specialist assisting patients with practical daily skills.
• Paraplegia: Paralysis of the lower half of the body.
• Physical Therapist: Specialist restoring physical motion and strength.
• Plantar Fasciitis: Inflammation of the thick foot fascia.
• Pronation: Rotation turning the palm or sole backward/downward.
• Quadriplegia: Paralysis affecting all four body limbs.
• Rehabilitation: Process of restoring function after injury or disease.
• Rotator Cuff: Group of muscles/tendons stabilizing the shoulder joint.
• Skeletal Muscle: Voluntary, striated muscle attached to bones.
• Smooth Muscle: Involuntary, non-striated visceral muscle tissue.
• Sphincter: Ring-like muscle closing a bodily opening.
• Supination: Rotation turning the palm or sole upward/forward.
• Tendon: Nonelastic fibrous tissue connecting muscle to bone.
• Visceral Muscle: Smooth muscle found within internal organ structures.
• Voluntary Muscle: Muscle operated under conscious neurological control.

Medical Abbreviations

• ADL: Activities of Daily Living
• EMG: Electromyography
• IM: Intramuscular
• OT: Occupational Therapy / Occupational Therapist
• PT: Physical Therapy / Physical Therapist
• RICE: Rest, Ice, Compression, Elevation
• ROM: Range of Motion
• TENS: Transcutaneous Electrical Nerve Stimulation