level 3: Chapter 8 – Muscular System

Vocabulary flashcards summarizing key terms, structures, disorders, and major muscles from Chapter 8 on the muscular system.

Involuntary muscle

Muscle tissue that contracts without conscious control; includes smooth and cardiac muscle.

Voluntary muscle

Muscle tissue under conscious control; skeletal muscle.

Tendon

A cord-like band of connective tissue that connects muscle to bone.

Neuromuscular junction (NMJ)

The synapse where a motor neuron releases acetylcholine to stimulate a skeletal muscle fiber and start an action potential.

Myosin

Thick contractile protein filament within skeletal muscle fibers.

Actin

Thin contractile protein filament within skeletal muscle fibers.

Calcium (Ca²⁺)

Electrolyte whose release into the sarcoplasm triggers muscle contraction.

Myoglobin

Oxygen-binding pigment in muscle cells that stores O₂ for aerobic metabolism.

Creatine phosphate

High-energy compound that donates phosphate to ADP, rapidly regenerating ATP in muscle cells.

Resistance training

Weight-lifting or similar exercise that produces muscle hypertrophy (increase in size).

Aerobic exercise

Endurance-type activity (e.g., running, cycling) that improves muscular stamina and cardiovascular fitness.

Isotonic contraction

Muscle contraction in which the muscle changes length, producing movement.

Isometric contraction

Muscle contraction that develops tension without changing muscle length.

Origin (muscle attachment)

The fixed, less-movable bone attachment point of a muscle.

Insertion (muscle attachment)

The more-movable bone attachment point where muscle action occurs.

Antagonist muscle

Muscle that relaxes or lengthens to allow the prime mover to accomplish a movement.

Muscle atrophy

Wasting or loss of muscle tissue, typically caused by disuse.

Muscle strain

Tearing of muscle fibers or the musculotendinous junction, often called a “pulled muscle.”

Rhabdomyolysis

Life-threatening skeletal muscle necrosis, often from extreme overtraining, releasing creatine kinase that can damage kidneys.

Duchenne muscular dystrophy

Inherited absence of dystrophin protein causing progressive muscle degeneration, weakness, and replacement with scar tissue.

Myasthenia gravis

Autoimmune disorder in which antibodies destroy acetylcholine receptors, producing muscle weakness.

Myalgia

Muscular pain.

Fibromyalgia syndrome

Chronic condition marked by widespread pain, fatigue, sleep disturbance, memory, and mood issues.

Plantar fasciitis

Inflammation of the plantar fascia on the sole of the foot.

Sternocleidomastoid

Lateral neck muscle that rotates and flexes the head.

Trapezius

Large upper-back muscle that elevates shoulders and extends the neck.

Pectoralis major

Anterior chest muscle that adducts and flexes the arm.

Deltoid

Lateral shoulder muscle that abducts the arm.

Biceps brachii

Anterior arm muscle that flexes the forearm at the elbow.

Triceps brachii

Posterior arm muscle that extends the forearm at the elbow.

Flexor carpi group

Anterior forearm muscles that flex the hand at the wrist.

Extensor carpi group

Posterior forearm muscles that extend the hand at the wrist.

Diaphragm

Dome-shaped muscle between thorax and abdomen; the primary muscle of breathing.

Rectus abdominis

Anterior abdominal muscle that flexes the vertebral column.

Erector spinae

Deep back muscle group that extends the vertebral column.

Gluteus maximus

Large posterior pelvic muscle that extends and laterally rotates the thigh.

Quadriceps femoris

Anterior thigh muscle group that extends the leg at the knee.

Hamstring group

Posterior thigh muscles that flex the leg at the knee and extend the thigh.

Gastrocnemius

Calf muscle that plantar-flexes the foot.

Tibialis anterior

Anterior leg muscle that dorsiflexes the foot.