Muscular System Why do people lift weights? Why do we exercise our muscles? Over 600 muscles make up muscular system 45% of total body weight of an adult Made up of bundles of muscle fibers (long slender cells) held together by connective tissue

Key Word Parts My/o-, mys-, and sarco- refer to muscle Spas- (draw, pull), tens- (stretch), -plegia (paralysis), therap- (treatment), therm- (heat), dynam- (power) Myo-, mys-, and sarco- refer to muscle Spas- (draw, pull), tens- (stretch), -plegia (paralysis), therap- (treatment), therm- (heat), dynam- (power

Functions The human body has more than 600 muscles The functions of the muscular system Movement Maintain Posture Stabilization of joints Generation of heat Protection of some internal organs Movement: locomotion/manipulation, - (muscle action such as walking aids the flow of blood through veins as it returns to the heart) heartbeat, moving substances through hollow organs (e.g., food thru the digestive system; fluid through the ducts and tubes associated with othe body systems (i.e., circulatory/lymphatic) Posture maintenance Stabilization of joints Generation of heat – muscle movement generates 85% of body heat Protection of some internal organs

Structures Muscle Fibers -(mean thread like) are long, slender cells Fascia - Tough, sheet or band of fibrous connective tissue that covers, supports and separates muscle Tendons - Narrow, band of non-elastic, dense, fibrous connective tissue that attaches a muscle to a bone Aponeurosis- broad, flat sheet of fibrous connective tissue that is similar to a tendon; however an aponeurosis attaches a muscle to bone OR to other tissues Over 600 muscles 45% of total body weight of an adult These muscles are made up of fibers, covered with fascia, and attached to bones by tendons Fibers – (mean thread like) are long, slender cells Each muscle is held together by connective tissue and enclosed In a fibrous sheath Fascia Tough, sheet or band of fibrous connective tissue that covers, supports and separates muscle (the muscle membrane) Example: lumbodorsal fascia which surround the deep muscles of the trunk and back Tendon Narrow, band of nonelastic, dense, fibrous connective tissue that attaches a muscle to a bone Examples: Achilles tendon which attaches the gastrocnemius muscle on the calf of the leg to the heel bone Aponeurosis: broad, flat sheet of fibrous connective tissue that is similar to a tendon; however an aponeurosis attaches a muscle to bone OR to other tissues Example: Abdominal aponeurosis

Types of Muscles Cardiac Visceral/Smooth Skeletal

Cardiac Form walls of heart Contract to circulate blood Striated (banded) Involuntary Efferent nerves control rate of contraction Afferent nerves concerned with sensations Contract at steady rate except for brief bursts of rapid rate, automaticity Cardiac Form walls of heart Contract to circulate blood Striated (banded) with lots of mitochondria Involuntary: function without conscious thought or control (autonomic nervous system control) Efferent (motor) nerves control rate of contraction based on needs of the body Afferent (sensation) nerves concerned with sensations of pain, spasm, and stretch Contract at steady rate except for brief bursts of rapid rate, automaticity

Visceral/smooth Found in the internal organs of the body Walls of hollow, visceral organs No striations = smooth Involuntary Efferent (motor) neurons less important Afferent nerves concerned with sensations of pain, spasm, and stretch Steady constant contractions, automaticity Found in the internal organs of the body such as the digestive system, respiratory system, blood vessels, and eyes Form the Walls of hollow, visceral organs No striations = smooth Involuntary: function without conscious thought or control (autonomic nervous system control) Efferent (motor) neurons less important Afferent nerves concerned with sensations of pain, spasm, and stretch Steady constant contractions, automaticity

Skeletal Attaches to and covers bony skeleton Longest fibers of all muscle cells Striated Voluntary (central and peripheral nervous system control) Efferent nerve fibers from brain and spinal cord send impulses for contraction Afferent nerve fibers from muscle send message to CNS to inform brain of the degree of contraction Skeletal 40% of body Attaches to and cover bony skeleton Longest fibers of all muscle cells Striated (have dark and light bands that produce striped appearance) Voluntary: person has control over their action (central and peripheral nervous system control) Efferent nerve fibers from brain and spinal cord send impulses for contraction Afferent nerve fibers from muscle send message to CNS to inform brain of the degree of contraction Contract rapidly, tire easily, tremendous power, adaptable Cause body movement

Properties Excitability: ability to receive & respond to stimulus Contractility: ability to shorten forcibly Extensibility: ability to be stretched Elasticity: ability to resume resting length (of muscle fiber) after being stretched Automaticity: ability of muscle to contract without a nerve supply

Contractility When muscle fibers are stimulated by nerves they contract (become short and thick) which causes movement Contraction depends on myofilaments: actin and myosin When muscle fibers are stimulated by nerves they contract (become short and thick) which causes movement Contraction involves protein filaments: actin and myosin When one muscle of a pair (antagonistic pair) contracts the other relaxes

Muscle Contraction Isotonic contraction is muscle shortening that produces movement Muscle tone or tonus is a state of partial contraction that maintains a person’s posture Isometric contraction does not cause muscle shortening or movement A twitch is a quick, jerky contraction of a whole muscle from one stimulus Muscle Tone Steady partial contraction present at all times State of tension when awake State of readiness to act; enables muscles for immediate response Does not produce active movement Keeps muscles firm healthy Stabilizes joints Maintains posture

Muscle Contraction (continued) Tetanic contraction is more sustained than a twitch and is caused by many stimuli in rapid succession Fibrillation is uncoordinated contraction of muscle fibers Convulsions are contractions of groups of muscles in an abnormal manner Spasms are involuntary, sudden, and prolonged contractions

All or None Response Once the muscle fiber has been stimulated to contract, the muscle fiber will contract to its fullest extent Each muscle is served by at least one motor nerve, which contains hundreds of neuromuscular junctions with each single muscle fiber Motor neuron and all the muscle fibers that it supplies is called a motor unit When a motor neuron fires, all the muscle fibers that it innervates respond by contracting Average 150 muscle fibers per motor unit Average 4 to several hundred muscle fibers per motor unit for fine motor control i.e. controlling fingers and eye movements All or None Response Once the muscle fiber has been stimulated to contract, the muscle fiber will contract to its fullest extent Each muscle is served by at least one motor nerve, which contains hundreds of neuromuscular junctions with each single muscle fiber Motor neuron and all the muscle fibers that it supplies is called a motor unit When a motor neuron fires, all the muscle fibers that it innervates respond by contracting Average 150 muscle fibers per motor unit Average 4 to several hundred muscle fibers per motor unit for fine motor control i.e. controlling fingers and eye movements

Loss of muscle tone When muscles are not used for a long period of time: atrophy, waste away (degeneration and loss of mass) Complete immobilization - strength decreases 5% per day; paralysis = atrophy to ¼ initial size; eventually muscle tissue replaced by fibrous connective tissue Lack of use can result in contracture Severe tightening of a flexor muscle Results in bending of a joint Loss of muscle tone Can occur in severe illness such as paralysis, palsy When muscles are not used for a long period of time: atrophy, waste away (degeneration and loss of mass) Complete immobilization of muscle (complete bed rest or loss of neural stimulation or in a cast): strength decreases 5% per day; paralysis = atrophy to ¼ initial size; muscle tissue replaced by fibrous connective tissue - muscle rehabilitation impossible; delay with electrical stimulation Lack of use can result in contracture (permanent contraction of muscle due to spasm or paralysis) Severe tightening of a flexor muscle Results in bending of a joint When no ATP available, state of continuous contraction results because crossbridges are unable to detach Foot drop = common Fingers, wrists and knees as well as other joints can be affected

Muscle fatigue Muscle unable to contract Tension drops to zero Inability to generate enough ATP to power the contractile process Relative deficit of ATP NOT total absence Excessive accumulation of lactic acid and ionic imbalances Muscle fatigue Muscle unable to contract Tension drops to zero Inability to generate enough ATP to power the contractile process Relative deficit of ATP NOT total absence Excessive accumulation of lactic acid and ionic imbalances

Other Conditions Spasm: sudden involuntary contraction of muscle Clonic: alternating spasm with relaxation Tonic: sustained Tetanus: smooth sustained contraction Tetany: result of low calcium; increases excitability of neurons; loss of sensation, muscles twitching, convulsions; untreated - spasms of larynx, respiratory paralysis, death Spasm: sudden involuntary contraction of muscle Clonic: alternating spasm with relaxation Tonic: sustained Tetanus: smooth sustained contraction Tetany: result of low calcium; increases excitability of neurons; loss of sensation, muscles twitching, convulsions; untreated - spasms of larynx, respiratory paralysis, death

Interactions of Skeletal Muscles Prime Mover/Agonist Provides major force for producing a specific movement Initiates movement Example: biceps brachii - elbow flexion Antagonist Oppose or reverse a particular movement Example: triceps brachii - elbow extension Synergist Aid agonists by promotion of same movement or by reducing undesirable/unnecessary movements Example: muscles which help make fist without bending wrist Fixator Synergists which immobilize a bone or a muscle origin Example: muscles to stabilize scapula Interactions of Skeletal Muscles – muscles are made of antagonistic pairs – (work opposite each other). In the pair, one muscle produces movement in one way and the other muscle produces movement in the opposite direction Muscles do not act independently Prime Mover/Agonist Provides major force for producing a specific movement Initiates movement Example: biceps brachii - elbow flexion Antagonist Oppose or reverse a particular movement Example: triceps brachii - elbow extension Synergist Aid agonists by promotion of same movement or by reducing undesirable/unnecessary movements Example: muscles which help make fist without bending wrist Fixator Synergists which immobilize a bone or a muscle origin Example: muscles to stabilize scapula

Actions or Movements of Skeletal Muscles Goniometry: measurement of joint movement Adduction: moving a body part toward the midline Abduction: moving a body part away from the midline Flexion: decreasing the angle at a joint Extension: increasing the angle at a joint Hyperextension: increases the angle beyond the anatomical position Circumduction: the distal end of an extremity inscribes a circle while the shaft inscribes a cone Actions or Movements of Skeletal Muscles Goniometry: measurement of joint movement Adduction: moving a body part toward the midline Abduction: moving a body part away from the midline Flexion: decreasing the angle at a joint Extension: increasing the angle at a joint Hyperextension: increases the angle beyond the anatomical position Circumduction: the distal end of an extremity inscribes a circle while the shaft inscribes a cone

Actions or Movements of Skeletal Muscles Rotation: revolving a part about the longitudinal axis Internal: move toward the midline or medially External: move away from the midline or laterally Supination: turn the palm upward; “what’s up?” Pronation: turn the palm downward Inversion: turn the plantar surface away from the midline Plantar flexion (extension): move the sole of the foot downward as in standing on the toes Dorsiflexion: move the sole of the foot upward Range of Motion – change in joint position produced by the muscles Rotation: revolving a part about the longitudinal axis Internal: move toward the midline or medially External: move away from the midline or laterally Supination: turn the palm upward; “what’s up?” Pronation: turn the palm downward Inversion: turn the plantar surface away from the midline Plantar flexion (extension): move the sole of the foot downward as in standing on the toes Dorsiflexion: move the sole of the foot upward

Figure 14-5 Basic Types of Muscle Movement

Muscle Nomenclature Location i.e. vastus lateral and vastus medialis; external and internal oblique, pectoralis Origin and insertion i.e. brachioradialis, occipitofrontal Function/Action i.e. ulnar flexor (flexes wrist), extensor capri muscles (extension motions of the wrists) Muscle Nomenclature – named for their: Location i.e. vastus lateral (toward the side) and vastus medialis (toward the midline); external (near the surface) and internal (deeper) oblique, pectoralis Origin and insertion (origin is the place where the muscle begins- the fixed attachment and insertion is the place where the muscle ends (inserts) – the moveable end or the portion farthest from the midline of the body, i.e. occipitofrontal Number of heads i.e. biceps, triceps Function i.e. ulnar flexor (flexes wrist), extensor capri muscles (extension motions of the wrists)

Muscle Nomenclature Number of heads/divisions forming them i.e. biceps, triceps Size i.e. gluteus maximus Shape i.e.deltoid Fiber direction i.e. rectus abdominus (straight muscle of abdomen), orbicularis oris (circular around mouth) Size i.e. gluteus maximus (largest of the buttock) Shape i.e.deltoid – shaped like an inverted triangle Orientation of bundles of muscle fibers i.e. rectus abdominus (straight muscle of abdomen), orbicularis oris (circular around mouth)

Adjectives to describe muscles bi-, tri-, quadri- : 2, 3, 4 Externus: exterior Gracilis: slender Latissimus: wide Longissimus: long Longus: long Medius: intermediate Adjectives to describe muscles bi-, tri-, quadri- : 2, 3, 4 Externus: exterior Gracilis: slender Latissimus: wide Longissimus: long Longus: long Medius: intermediate Orbicularis: around Quadratus: square Rectus: straight Rhomboideus: diamond shaped Scalenes: irregular triangle Teres: round Transverse: crosswise Vastus: great

Adjectives to describe muscles Orbicularis: around Quadratus: square Rectus: straight Rhomboideus: diamond shaped Scalenes: irregular triangle Teres: round Transverse: crosswise Vastus: great

Medical Specialties Orthopedic Surgeon Rheumatologist Neurologist Sports Medicine Physical Therapist Chiropractor = manipulative treatmetn of disorders originating from misalignment of the spine Orthotics = braces or splints to align, support, prevent or correct deformities or to improve the function of movement Osteopathic Physician – DO – specializes in treating health problems by manipulation. Orthopedic Surgeon = tx injuries and disorders involving the bones, joints, muscles and tendons Podiatrist = dx and tx of the foot Rheumatologist = tx disorders that involve the inflammation of connective tissues including muscles Neurologist = tx the cause of paralysis and similar muscular disorders in which there is a loss of function Sports medicine -= treats sports related injuries Physical Therapy =

Assessment Techniques Reflex tests Joint motion Blood tests Electromyography tests Muscle biopsy Reflex tests- DTR with a reflex hammer Joint motion - ROM testing Blood tests Electromyography tests – also known as nerve conduction studies – tests and record neuromuscular activity by the electric stimulation of nerve fibers to and from the muscle Muscle biopsy

Treatment Procedures of the Muscular System Medications – Anti-inflammatory antispasmodics (anticholinergics) Muscle relaxants Physical Therapy ROM ADLs

Treatment Procedures of the Muscular System Fascia (sheet or band of connective fibrous connective tissue that covers, supports, and seperates muscles) Fasciotomy Facioplasty Muscles Myectomy Mypoplasty Myorrhaphy Fascia (sheet or band of connective fibrous connective tissue that covers, supports, and seperates muscles) Fasciotomy – otomy – surgical incision Facioplasty - plasty = surgical repair Muscles Myectomy= surgical removal Mypoplasty= surgical repair Myorrhaphy = to suture a muscle wound

Treatment Procedures of the Muscular System Tendon Carpal tunnel release Tenectomy Tenodesis Tenolysis Tenonectomy Tenotomy Tenoplasty Tenorrhaphy Carpal tunnel release – cutting of the carpal ligament to relieve nerve pressure Tenectomy – surgical removal of a lesion from a tendon Tenodesis –to suture the end of a tendon to bone (desis = to tie together/bind) Tenolysis – to free a tendon from adhesionsl (lysis = to set free) Tenonectomy= surgical removal of part of a tendon for the purpose of shortening Tenotomy = also known as tendotomy = surgical division of a tendonfor relief of a deformaty caused by abnormal sortening Tenoplasty = surgical repair Tenorrhaphy = suturing of a divided tendon

Proud of your Muscles?