Exercise Science Section 3: The Muscular System An Introduction to Health and Physical Education Ted Temertzoglou Paul Challen ISBN 1-55077-132-9 Major Functions of Muscles Movement Includes: breathing, eating, and the beating of our hearts Support Heat production There are over 600 muscles in the human body. Three Types of Muscle Tissue Skeletal muscles: Voluntary, striated, and attach to bones by tendons and other tissue Cardiac muscles: Involuntary, striated, and found in one place the heart Smooth muscles: Involuntary, non-striated, and surround the body s internal organs Skeletal muscle Cardiac muscle Smooth muscle
Properties of Muscle Fibre Irritability Contractibility Elasticity Extensibility Refers to muscle responding to stimuli Refers to muscle shortening in length Refers to muscle stretching and returning to normal position Refers to muscle extending in length Conductivity Refers to muscle transmitting nerve impulses Neuromuscular Junction Axon Neurotransmitter acetylcholine (Ach) Axon Terminal Sarcolemma Synaptic Cleft Receptor The Motor Unit Dendrites Neuron cell body Axon hillock Motor neuron Direction of action potential Myelin sheath Neurolemma Neuromuscular junction Terminal branches Muscle fibres Motor end plate
The Anatomy of Skeletal Muscle Muscle fibre looking outward: Perimysium Binds muscle fibres together Epimysium Sheath enveloping entire muscle Muscle fibre looking inward: Endomysium Sheath of connective tissue surrounding muscle fibre Sarcolemma Contains cytoplasm (sarcoplasm) Myofibrils Contain actin and myosin Sarcomeres Contains myosin and actin Perimysium Muscle fibre Tendon Muscle belly Epimysium Endomysium Muscle Fibre Muscle belly Epimysium Perimysium Z line Sarcomere Z line Tendon Muscle Fibre Thick filament Thin filament Sarcomere Sarcolemma Sarcoplasmic reticulum Myofibril How Muscles Are Named Action/Function Direction of Fibres Location Number of Divisions/Heads Shape Points of Attachment Flexion/Extension Rectus/Transversus Anterior/Posterior Number of heads Deltoid/Trapezius Sternum/Clavicle/Mastoid process
How Muscles Attach to Bone Indirect attachment: Epimysium extends past muscle as a tendon Attaches to periosteum of bone Direct attachment: Epimysium adheres to and fuses with the periosteum Point of attachment Antagonistic Pairs Examples Agonist (Prime Mover) Antagonist (Counteracts) Elbow flexion Biceps brachii Triceps brachii Shoulder abduction Deltoid Latissimus dorsi Medial shoulder rotation Pectoralis major Infraspinatus Knee extension Quadriceps Hamstrings Wrist flexion Flexor carpi radialis Extensor carpi radialis Dorsi flexion Tibialis anterior Gastrocnemius Trunk flexion Rectus abdominis Erector spinae group Hip flexion Iliopsoas Gluteus maximus Origin, Insertion, and Function Origin: Proximal attachment Where muscle attaches to the least moveable area of the bones of the axial skeleton Insertion: Distal attachment Where muscle attaches to the bone that is moved most Function: Action/motion What the muscle does when activated Origin Insertion
Types of Muscle Contraction Concentric: Muscle fibres shorten Eccentric: Muscle fibres lengthen Isometric: Muscle fibres do not change in length Muscle Contraction During Exercise Isotonic exercise Controlled shortening and lengthening of the muscle Isometric exercise No motion muscle fibres maintain a constant length throughout contraction Isokinetic exercise Use machines to control speed of contractions Combines best features of both isotonic and isometric training i Stockphoto.com/ M ax Delson The Sliding Filament Theory Myosin crossbridges (small bridges on the thick filaments that extend to the thin filaments): Attach, rotate, detach, and reattach in rapid succession Results in the sliding or overlap of the actin and myosin filaments Causes sarcomere to contract (muscle contraction) Known as the sliding filament theory
The Sliding Filament Theory Myosin crossbridges (small bridges on the thick filaments that extend to the thin filaments) The Sliding Filament Theory Myosin crossbridges Attach, rotate, detach, and re-attach in rapid succession The Sliding Filament Theory Myosin crossbridges Results in the sliding or overlap of the actin and myosin filaments Causes sarcomere to contract (muscle contraction)
The Role of Adenosine Triphosphate The sliding filament theory at the molecular level: Nerve impulse transmitted through the muscle fibre and releases calcium ions Calcium (in presence of troponin and tropomyosin) facilitates the interaction of myosin and actin molecules Adenosine triphosphate (ATP) is the energy source behind the release of calcium ATP detaches myosin from the actin molecule ATP must be replaced through food metabolism for process to continue The Role of Calcium Sarcolemma Outer vessicle of sarcoplasmic reticulum (Terminal cisternae) Longitudinal tubules of sarcoplasmic reticulum Transverse tubule (T-tubule) H zone Triad Terminal cisternae Transverse tubule Terminal cisternae A band Z line I band Myofibrils Anterior Muscles
Posterior Muscles Muscles of the Neck Semispinalis capitis Splenius Sternocleidomastoid Scalenus medius Scalenus anterior Muscles of the Vertebral Column Nuchal line Occipital bone Mastoid process Spinalis Longissimus Iliocostalis Erector spinae group
Muscles of Respiration Internal thoracic artery and vein Sternum Internal intercostals Transversus thoracis Diaphragm (thoracic) Transversus abdominis Muscles of the Abdomen External oblique Rectus abdominis Quadratus lumborum (deep) Muscles of the Shoulder Clavicular head of pectoralis major Sterncostal head of pectoralis major
Muscles of the Shoulder cont d Supraspinatus Infraspinatus Infraspinatus Latissimus dorsi Muscles of the Rotator Cuff Supraspinatus Teres minor Infraspinatus Muscles of the Rotator Cuff cont d Subscapularis
Muscles that Act on the Scapula Trapezius Levator scapulae Rhomboid minor Rhomboid major Teres major Muscles that Act on the Scapula cont d Teres major Muscles that Move the Humerus Deltoid (anterior and lateral heads) Coracobrachialis
Muscles that Move the Humerus cont d Coracobrachialis Pectoralis minor Serratus anterior Elbow Flexors / Extensors Anterior Biceps brachii Brachialis Pronator teres Brachioradialis Elbow Flexors / Extensors Posterior Triceps brachii (short head) Triceps brachii (long head)
Muscles of the Forearm Anterior Biceps brachii Pronator teres Brachioradialis Pronator quadratus (deep) Muscles of the Forearm Posterior Brachioradialis Triceps brachii (lateral head) Anconeus Muscles of the Forearm Posterior (deep) Supinator
Extrinsic Hand Muscles Anterior Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis Extrinsic Hand Muscles Posterior Extensor carpi radialis longus Extensor digitorum Extensor carpi ulnaris Extensor carpi radialis brevis Extensor digit minimi Intrinsic Hand Muscles Thenar eminence Hypothenar eminence
Muscles of the Hip Anterior Psoas minor Psoas major Iliacus Tensor fasciae latae Sartorius Iliopsoas Pectineus Gracilis Rectus femoris Iliotibial tract (band) Muscles of the Hip Posterior Gluteus medius Gluteus maximus (cut) Gluteus minimus Gracilis Muscles of the Hip Anterior (adductors) Pectineus (cut) Adductor brevis Adductor longus Adductor group Adductor magnus
Muscles of the Thigh Anterior Quadriceps femoris group Rectus femoris Vastus intermedius (underneath) Vastus lateralis Vastus medialis Muscles of the Thigh Posterior Semitendinosus Biceps femoris Hamstring muscle group Semimembranosus Extrinsic Foot Muscles Anterior Extensor digitorum longus Tibialis anterior Extensor hallucis longus
Extrinsic Foot Muscles Posterior Gastrocnemius (medial and lateral heads) Soleus Calcaneal tendon (Achilles tendon) Extrinsic Foot Muscles Posterior (deep) Popliteus Tibialis posterior Flexor digitorum longus Fibularis (Peroneus) longus Flexor hallucis longus Fibularis (Peroneus) brevis Intrinsic Foot Muscles Superficial Flexor digitorum brevis
Intrinsic Foot Muscles Intermediate Quadratus plantae Intrinsic Foot Muscles Deep Flexor hallucis brevis