Muscular System Anatomy PDF

 Functions 1. Movement of the body 2. Maintenance of posture 3. Production of body heat 4. Respiration  Functions 5. Communication 6. Constriction of organs and vessels 7. Contraction of heart  General Properties Of Muscle Tissue 1. Contrac...

 Functions 1. Movement of the body 2. Maintenance of posture 3. Production of body heat 4. Respiration  Functions 5. Communication 6. Constriction of organs and vessels 7. Contraction of heart  General Properties Of Muscle Tissue 1. Contractility The ability of muscle to shorten, or contract 2. Excitability The capacity of muscle to respond to stimulus  General Properties Of Muscle Tissue 3. Extensibility The ability to be stretched 4. Elasticity The ability to recoil after being stretched Characteristics Of Skeletal Muscle Striated Muscle Characteristics Of Skeletal Muscle 40% of body weight Most are attached to the bones HISTOLOGY  EPIMYSIUM A sheet of connective fibrous tissue that surrounds a muscle Fascia – Outer Epimysium - Inner  FASCICLES A bundle of skeletal muscle fibers running parallel to each other  PERIMYSIUM Connective tissue that separates muscle fascicles from each other  ENDOMYSIUM Loose connective tissue that surrounds each muscle fiber MUSCLE FIBERS Muscle Cells or Myocytes Multinucleated Up to 30 cm in length Muscle Fiber Structure  Sarcolemma The cell membrane of the muscle fiber  Sarcoplasm The cytoplasm of the muscle fiber Transverse Tubules T Tubules Tubelike inward folds in the sarcolemma Connected to a Sarcoplasmic Reticulum  Sarcoplasmic Reticulum Smooth endoplasmic reticulum of a muscle fiber For storage of calcium ions needed for muscle contraction  Myofibrils Bundles of protein fibers within a muscle fiber Responsible for contraction  Myofibrils Actin Filament (Thin) Myosin Filament (Thick) Sliding Filament Theory Sliding Filament Theory Sliding Filament Theory Motor unit  MOTOR UNIT Motor Neuron + Muscle Fiber/s  MOTOR NEURON Specialized nerve cells that stimulate muscles to contract  SYNAPSE Generalized term for cell-to-cell junction  SYNAPSE Examples of Synapses: 1. Neuron-to-Neuron 2. Neuron-to-Effector Cell (Organ) 3. Neuromuscular Junction  Presynaptic Terminal Enlarged axon terminals resting on indentations in sarcolemma  Synaptic Cleft The space between the presynaptic terminal and the muscle fiber membrane  Postsynaptic Membrane The sarcolemma of the muscle fiber Synaptic Vesicles Small vesicles containing neurotransmitters Acetylcholine Motor Unit An action potential is generated Action potential is transmitting Saltatory Conduction in the Nodes of Ranvier Saltatory Conduction in the Nodes of Ranvier Saltatory Conduction in the Nodes of Ranvier Saltatory Conduction in the Nodes of Ranvier Saltatory Conduction in the Nodes of Ranvier Action potentials reach the axon terminals Action potential reaches the presynaptic cleft Calcium ions enter the axon terminal Calcium ions bind to the synaptic vesicles Acetylcholine neurotransmitters are released Acetylcholine exits into the synaptic cleft  Acetylcholine binds to their receptors in the sarcolemma Stimulates muscle contraction MYOGLOBIN Muscle needs high amount of oxygen The more myoglobin molecules in a muscle fiber, the redder is the muscle The “blood” in a meat is not blood, but myoglobin Exercise increases blood flow to the muscles Number of mitochondria increases Number of myofibrils and myofilaments increase Muscle fibers enlarge Hypertrophy Types of Contractions Isometric Isotonic Concentric Eccentric  Isometric = Equal Length ISOMETRIC Increase in tension of the muscle without changing its length  Isotonic = Equal Tension ISOTONIC Constant amount of tension while decreasing the length of the muscle. Concentric Muscle tension increases as the muscle shortens.  Tension is maintained in a muscle, but the opposing Eccentric resistance causes the muscle to lengthen.  MUSCLE FATIGUE DOMS TETANUS RHABDOMYOLYSIS  Delayed-Onset Muscle Soreness (DOMS) Sensation of discomfort or pain in the skeletal muscles following physical activity Due to Eccentric Muscle Contraction Results from overuse of the muscle. ISOMETRIC CONTRACTION Muscle contracts but no shortening or lengthening CONCENTRIC CONTRACTION Muscle contracts and shortens ECCENTRIC CONTRACTION Muscle contracts and lengthens (stretched)  Delayed-Onset Muscle Soreness (DOMS) Etiologies: (1) Structural damage from high tension (2) Metabolic waste product accumulation (lactic acid) (3) Increased temperature -nerve endings are sensitive to temperatures 38-48 degrees Celsius -damage to the structural element in the muscle (4) Spastic Contracture General Principles  APONEUROSIS A connective tissue sheet that anchors or connects a muscle Epicranial Aponeurosis  RETINACULUM A connective tissue sheet that pass over or under tendons and keep them in place  ORIGIN The most stationary, or fixed, end of the muscle.  ORIGIN If multiple origins, they are called “heads”  INSERTION The end of the muscle attached to the bone undergoing the greatest movement.  BELLY The part of the muscle between the origin and the insertion  AGONIST The muscle that is shortening or contracting  ANTAGONIST The muscle that is lengthening or relaxing  PRIME MOVER The muscle that plays the major role in accomplishing the desired movement  SYNERGIST The muscle/s that assist/s the prime mover muscle Nomenclatures  LOCATION Pectoralis Muscle in the Chest Gluteus Muscle in the Buttocks  LOCATION Brachial Muscle in the Arm Tibialis muscle in the Leg  SIZE Gluteus Maximus Gluteus Medius Gluteus Minimus SIZE Longus means “Long” Brevis means “Short” SHAPE Deltoid Muscle Deltoid means “Triangular” SHAPE Quadratus Lumborum Muscle Quadratus means “Rectangular” SHAPE Teres Major Muscle Teres means “Round” SHAPE Orbicularis Oculi Muscle Orbicularis means “Sphincter-shaped” ORIENTATION OF FASCICLES Rectus Abdominis Muscle Rectus means “straight or parallel” Note the fibers in a straight direction ORIENTATION OF FASCICLES Internal Oblique Muscle Note the direction of fibers in an oblique fashion ORIGIN and INSERTION Sternocleidomastoid Muscle Origins – Sternum and Clavicle Insertion – Mastoid Process ORIGIN and INSERTION Brachioradialis Muscle Origin – Arm (brachium) Insertion – Radius NUMBER of HEADS Biceps Brachii Muscle 2 Origins or Heads NUMBER of HEADS Triceps Brachii Muscle 3 Origins or Heads NUMBER of HEADS Biceps Femoris Muscle 2 Origins or Heads FUNCTIONS Adductor Longus Muscle Adductor Brevis Muscle Adductor Magnus Muscle Adduction of the thigh FUNCTIONS Flexor Carpi Radialis Muscle Flexor Carpi Ulnaris Muscle Flexion at the elbow joint FUNCTIONS Extensor Digitorum Muscle Extension of the fingers MUSCLES OF THE BODY Muscles of the Head and Neck Depresses the mandible, opening the jaw  LUMBRICALS Flexion at the metacarpophalangeal joints Extension at the interphalangeal joints  femur patella PCL ACL tibia Anterior Cruciate Ligament (ACL) prevents sliding of femur backwards X ACL  Posterior Cruciate Ligament (PCL) prevents sliding of femur forward X PCL  Hip or above the hip Hip or below the hip  Largest muscle Gluteus Maximus Smallest muscle Stapedius Strongest muscle Masseter Longest muscle Sartorius “Hard-working” muscle Heart Muscles can’t push, they only pull.