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Muscular System Jade Mellin - Period 3 - Coggle Diagram
Muscular System
Jade Mellin - Period 3
Major functions of the muscular system
Movement: Helps the body move (walking, running, lifting).
Posture: Keeps the body upright.
Heat Production: Muscles create heat to keep body temperature normal.
Stabilization: Supports joints and protects organs.
Circulation: Heart pumps blood; smooth muscles move food and fluids.
3 types of muscles & their functions
Skeletal Muscle
Voluntary (you can control it).
Moves bones and body parts.
Striated (striped appearance).
Smooth Muscle
Involuntary (works automatically).
Found in organs like stomach, intestines, blood vessels.
Moves substances through the body.
Cardiac Muscle
Involuntary.
Found only in the heart.
Pumps blood; contracts nonstop.
Sarcomere
The smallest unit of muscle contraction.
Made of actin (thin) and myosin (thick) filaments.
When a muscle contracts, the sarcomere shortens as actin slides over myosin.
Neuromuscular Junction (NMJ)
Nerve releases ACh (acetylcholine) → ACh binds to muscle receptors → starts a muscle contraction signal.
The connection between a motor neuron and a muscle fiber.
Sliding Filament Theory
Explains how muscles contract.
Myosin heads attach to actin.
Myosin pulls actin inward like rowing.
Sarcomere shortens → muscle contracts.
ATP is required for myosin to release and repeat the cycle.
Action Potential in a Muscle Fiber
A nerve signal triggers sodium (Na⁺) to rush into the muscle fiber.
This creates an electrical charge (action potential).
The charge travels along the sarcolemma → into T-tubules → releases calcium from the sarcoplasmic reticulum → starts contraction.
Muscle Coverings (Connective Tissue)
Endomysium: Surrounds each muscle fiber.
Perimysium: Surrounds bundles of fibers (fascicles).
Epimysium: Surrounds the whole muscle.
Fascia: Surrounds groups of muscles.
Disorders of the Muscular System
Muscular Dystrophy: Genetic disorder causing muscle weakness and loss of muscle mass.
Fibromyalgia: Causes widespread muscle pain, tenderness, and fatigue.
Myasthenia Gravis: Autoimmune disorder that causes muscle weakness, especially in the face and limbs.
Cerebral Palsy: Brain disorder that affects muscle movement, coordination, and posture.
Myositis: Inflammation of the muscles, causing weakness and sometimes pain.
Skeletal Muscles
Anterior / Superior View (Front, Upper Body)
Head / Face: Frontalis, Masseter, Orbicularis oris, Orbicularis oculi, Zygomaticus
Neck: Sternocleidomastoid, Sternohyoid
Shoulder / Arm: Deltoid, Biceps brachii, Brachialis, Brachioradialis, Triceps brachii, Flexor carpi radialis, Flexor carpi ulnaris, Palmaris longus, Pronator teres
Chest / Torso: Pectoralis major, Rectus abdominis, External obliques, Serratus anterior
Hip / Thigh: Iliopsoas, Tensor fasciae latae, Pectineus
Anterior / Inferior View (Front, Lower Body)
Thigh / Leg: Adductor longus, Gracilis, Rectus femoris, Sartorius, Vastus lateralis, Vastus medialis, Iliotibial tract
Lower Leg / Foot: Fibularis longus, Extensor digitorum longus, Tibialis anterior, Gastrocnemius, Soleus
Posterior / Superior View (Back, Upper Body)
Head / Neck: Occipitalis, Sternocleidomastoid
Shoulder / Back: Trapezius, Deltoid, Infraspinatus, Teres major, Rhomboid major, Latissimus dorsi
Arm / Forearm: Brachioradialis, Triceps brachii, Extensor carpi radialis, Extensor carpi ulnaris, Flexor carpi ulnaris
Hip / Glutes: Gluteus maximus, Gluteus medius
Posterior / Inferior View (Back, Lower Body)
Lower Leg / Foot: Gastrocnemius, Soleus, Fibularis longus, Calcaneal (Achilles) tendon (not a muscle but important landmark)
Thigh / Leg: Biceps femoris, Adductor magnus, Semitendinosus, Semimembranosus, Gracilis