Muscular SystemMuscular System

Key Word PartsKey Word Parts My/o-, mys-, and sarco- refer to My/o-, mys-, and sarco- refer to

musclemuscle Spas- (draw, pull), tens- (stretch), Spas- (draw, pull), tens- (stretch),

-plegia (paralysis), therap- -plegia (paralysis), therap- (treatment), therm- (heat), (treatment), therm- (heat), dynam- (power) dynam- (power)

FunctionsFunctions

The human body has more than 600 The human body has more than 600 muscles muscles

The functions of the muscular systemThe functions of the muscular system

MovementMovement

Maintain PostureMaintain Posture

Stabilization of joints Stabilization of joints

Generation of heat Generation of heat

Protection of some internal organs Protection of some internal organs

Structures Structures Muscle Fibers -(mean thread like) are long, Muscle Fibers -(mean thread like) are long, slender cellsslender cellsFascia - Tough, sheet or band of fibrous Fascia - Tough, sheet or band of fibrous connective tissue that covers, supports and connective tissue that covers, supports and separates muscle separates muscle Tendons - Narrow, band of non-elastic, Tendons - Narrow, band of non-elastic, dense, fibrous connective tissue that dense, fibrous connective tissue that attaches a muscle to a bone attaches a muscle to a bone Aponeurosis- broad, flat sheet of fibrous Aponeurosis- broad, flat sheet of fibrous connective tissue that is similar to a tendon; connective tissue that is similar to a tendon; however an aponeurosis attaches a muscle however an aponeurosis attaches a muscle to bone OR to other tissuesto bone OR to other tissues

Types of Muscles Types of Muscles

CardiacCardiac

Visceral/SmoothVisceral/Smooth

SkeletalSkeletal

CardiacCardiac

Form walls of heart Form walls of heart Contract to circulate blood Contract to circulate blood Striated (banded) Striated (banded) InvoluntaryInvoluntaryEfferent nerves control rate of Efferent nerves control rate of contraction contraction Afferent nerves concerned with Afferent nerves concerned with sensations sensations Contract at steady rate except for Contract at steady rate except for brief bursts of rapid rate, brief bursts of rapid rate, automaticity automaticity

Visceral/smoothVisceral/smooth

Found in the internal organs of the Found in the internal organs of the bodybodyWalls of hollow, visceral organs Walls of hollow, visceral organs No striations = smooth No striations = smooth InvoluntaryInvoluntaryEfferent (motor) neurons less Efferent (motor) neurons less important important Afferent nerves concerned with Afferent nerves concerned with sensations of pain, spasm, and stretch sensations of pain, spasm, and stretch Steady constant contractions, Steady constant contractions, automaticity automaticity

Skeletal Skeletal

Attaches to and covers bony skeleton Attaches to and covers bony skeleton

Longest fibers of all muscle cells Longest fibers of all muscle cells

Striated Striated

Voluntary (central and peripheral nervous Voluntary (central and peripheral nervous system control) system control)

Efferent nerve fibers from brain and spinal Efferent nerve fibers from brain and spinal cord send impulses for contraction cord send impulses for contraction

Afferent nerve fibers from muscle send Afferent nerve fibers from muscle send message to CNS to inform brain of the message to CNS to inform brain of the degree of contraction degree of contraction

PropertiesPropertiesExcitability: ability to Excitability: ability to receive & respond to receive & respond to stimulusstimulus

Contractility: ability to Contractility: ability to shorten forciblyshorten forcibly

Extensibility: ability to be Extensibility: ability to be stretched stretched

Elasticity: ability to Elasticity: ability to resume resting length (of resume resting length (of muscle fiber) after being muscle fiber) after being stretched stretched

Automaticity: ability of Automaticity: ability of muscle to contract without muscle to contract without a nerve supplya nerve supply

ContractilityContractility When muscle When muscle

fibers are fibers are stimulated by stimulated by nerves they nerves they contract (become contract (become short and thick) short and thick) which causes which causes movementmovement

Contraction Contraction depends on depends on myofilaments: myofilaments: actin and myosin actin and myosin

Muscle ContractionMuscle Contraction

Isotonic contraction is muscle shortening Isotonic contraction is muscle shortening that produces movementthat produces movement

Muscle tone or tonus is a state of partial Muscle tone or tonus is a state of partial contraction that maintains a person’s contraction that maintains a person’s postureposture

Isometric contraction does not cause Isometric contraction does not cause muscle shortening or movementmuscle shortening or movement

A twitch is a quick, jerky contraction of a A twitch is a quick, jerky contraction of a whole muscle from one stimuluswhole muscle from one stimulus

Muscle Contraction Muscle Contraction (continued)(continued)

Tetanic contraction is more sustained than Tetanic contraction is more sustained than a twitch and is caused by many stimuli in a twitch and is caused by many stimuli in rapid successionrapid successionFibrillation is uncoordinated contraction of Fibrillation is uncoordinated contraction of muscle fibersmuscle fibersConvulsions are contractions of groups of Convulsions are contractions of groups of muscles in an abnormal mannermuscles in an abnormal mannerSpasmsSpasms are involuntary, sudden, and are involuntary, sudden, and prolonged contractions prolonged contractions

All or None ResponseAll or None ResponseOnce the muscle fiber has been stimulated to contract, the Once the muscle fiber has been stimulated to contract, the muscle fiber will contract to its fullest extent muscle fiber will contract to its fullest extent

Each muscle is served by at least one motor nerve, which Each muscle is served by at least one motor nerve, which contains hundreds of neuromuscular junctions with each contains hundreds of neuromuscular junctions with each single muscle fiber single muscle fiber

Motor neuron and all the muscle fibers that it supplies is Motor neuron and all the muscle fibers that it supplies is called a motor unit called a motor unit

When a motor neuron fires, all the muscle fibers that it When a motor neuron fires, all the muscle fibers that it innervates respond by contracting innervates respond by contracting

Average 150 muscle fibers per motor unit Average 150 muscle fibers per motor unit

Average 4 to several hundred 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 for fine motor control i.e. controlling fingers and eye movements movements

Loss of muscle tone Loss of muscle tone

When muscles are not used for a long When muscles are not used for a long period of time: atrophy, waste away period of time: atrophy, waste away (degeneration and loss of mass) (degeneration and loss of mass)

Complete immobilization - strength Complete immobilization - strength decreases 5% per day; paralysis = decreases 5% per day; paralysis = atrophy to ¼ initial size; eventually atrophy to ¼ initial size; eventually muscle tissue replaced by fibrous muscle tissue replaced by fibrous connective tissueconnective tissue

Lack of use can result in contractureLack of use can result in contractureSevere tightening of a flexor muscle Severe tightening of a flexor muscle Results in bending of a joint Results in bending of a joint

Muscle fatigue Muscle fatigue

– Muscle unable to contract Muscle unable to contract – Tension drops to zero Tension drops to zero – Inability to generate enough Inability to generate enough

ATP to power the contractile ATP to power the contractile process process

– Relative deficit of ATP NOT Relative deficit of ATP NOT total absence total absence

– Excessive accumulation of Excessive accumulation of lactic acid and ionic lactic acid and ionic imbalances imbalances

Other ConditionsOther ConditionsSpasm: sudden involuntary Spasm: sudden involuntary contraction of muscle contraction of muscle

Clonic: alternating spasm with Clonic: alternating spasm with relaxation relaxation

Tonic: sustained Tonic: sustained

Tetanus: smooth sustained Tetanus: smooth sustained contraction contraction

Tetany: result of low calcium; Tetany: result of low calcium; increases excitability of neurons; loss increases excitability of neurons; loss of sensation, muscles twitching, of sensation, muscles twitching, convulsions; untreated - spasms of convulsions; untreated - spasms of larynx, respiratory paralysis, death larynx, respiratory paralysis, death

Interactions of Skeletal MusclesInteractions of Skeletal Muscles– Prime Mover/Agonist Prime Mover/Agonist

Provides major force for producing a specific Provides major force for producing a specific movement movement Initiates movement Initiates movement Example: biceps brachii - elbow flexion Example: biceps brachii - elbow flexion

– Antagonist Antagonist Oppose or reverse a particular movement Oppose or reverse a particular movement Example: triceps brachii - elbow extension Example: triceps brachii - elbow extension

– Synergist Synergist Aid agonists by promotion of same movement or by Aid agonists by promotion of same movement or by reducing undesirable/unnecessary movements reducing undesirable/unnecessary movements Example: muscles which help make fist without Example: muscles which help make fist without bending wrist bending wrist

– Fixator Fixator Synergists which immobilize a bone or a muscle origin Synergists which immobilize a bone or a muscle origin Example: muscles to stabilize scapula Example: muscles to stabilize scapula

Actions or Movements of Skeletal Actions or Movements of Skeletal MusclesMuscles

– Goniometry: measurement of joint movement Goniometry: measurement of joint movement – Adduction: moving a body part toward the Adduction: moving a body part toward the

midline midline – Abduction: moving a body part away from the Abduction: moving a body part away from the

midline midline – Flexion: decreasing the angle at a joint Flexion: decreasing the angle at a joint – Extension: increasing the angle at a joint Extension: increasing the angle at a joint – Hyperextension: increases the angle beyond Hyperextension: increases the angle beyond

the anatomical position the anatomical position – Circumduction: the distal end of an extremity Circumduction: the distal end of an extremity

inscribes a circle while the shaft inscribes a inscribes a circle while the shaft inscribes a cone cone

Actions or Movements of Skeletal Actions or Movements of Skeletal MusclesMuscles

– Rotation: revolving a part about the longitudinal axis Rotation: revolving a part about the longitudinal axis Internal: move toward the midline or medially Internal: move toward the midline or medially External: move away from the midline or laterally External: move away from the midline or laterally

– Supination: turn the palm upward; “what’s up?” Supination: turn the palm upward; “what’s up?” – Pronation: turn the palm downward Pronation: turn the palm downward – Inversion: turn the plantar surface away from the Inversion: turn the plantar surface away from the

midline midline – Plantar flexion (extension): move the sole of the foot Plantar flexion (extension): move the sole of the foot

downward as in standing on the toes downward as in standing on the toes – Dorsiflexion: move the sole of the foot upward Dorsiflexion: move the sole of the foot upward – Range of Motion – change in joint position produced by Range of Motion – change in joint position produced by

the musclesthe muscles

Figure 14-5 Basic Types of Figure 14-5 Basic Types of Muscle MovementMuscle Movement

Muscle NomenclatureMuscle NomenclatureLocationLocation i.e. vastus i.e. vastus lateral and vastus lateral and vastus medialis; external medialis; external and internal oblique, and internal oblique, pectoralis pectoralis Origin and Origin and insertioninsertion i.e. i.e. brachioradialis, brachioradialis, occipitofrontal occipitofrontal Function/ActionFunction/Action i.e. i.e. ulnar flexor (flexes ulnar flexor (flexes wrist), extensor capri wrist), extensor capri muscles (extension muscles (extension motions of the wrists) motions of the wrists)

Muscle NomenclatureMuscle Nomenclature

Number of heads/divisions Number of heads/divisions forming themforming them i.e. biceps, triceps i.e. biceps, triceps

SizeSize i.e. gluteus maximus i.e. gluteus maximus

ShapeShape i.e.deltoid i.e.deltoid

Fiber directionFiber direction i.e. rectus i.e. rectus abdominus (straight muscle of abdominus (straight muscle of abdomen), orbicularis oris (circular abdomen), orbicularis oris (circular around mouth) around mouth)

Adjectives to describe musclesAdjectives to describe muscles

bi-, tri-, quadri- : bi-, tri-, quadri- : 2, 3, 4 2, 3, 4 Externus: Externus: exterior exterior Gracilis: slender Gracilis: slender Latissimus: Latissimus: wide wide Longissimus: Longissimus: long long Longus: long Longus: long Medius: Medius: intermediate intermediate

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

Medical SpecialtiesMedical Specialties

Orthopedic SurgeonOrthopedic Surgeon

RheumatologistRheumatologist

NeurologistNeurologist

Sports MedicineSports Medicine

Physical TherapistPhysical Therapist

Assessment TechniquesAssessment Techniques

Reflex testsReflex tests

Joint motionJoint motion

Blood testsBlood tests

Electromyography testsElectromyography tests

Muscle biopsyMuscle biopsy

Treatment Procedures of the Treatment Procedures of the Muscular SystemMuscular System

Medications – Medications – – Anti-inflammatoryAnti-inflammatory– antispasmodics (anticholinergics)antispasmodics (anticholinergics)– Muscle relaxantsMuscle relaxants

Physical TherapyPhysical Therapy– ROMROM– ADLsADLs

Treatment Procedures of the Treatment Procedures of the Muscular SystemMuscular System

Fascia (sheet or band of connective fibrous Fascia (sheet or band of connective fibrous connective tissue that covers, supports, connective tissue that covers, supports, and seperates muscles)and seperates muscles)– FasciotomyFasciotomy– FacioplastyFacioplasty

MusclesMuscles– MyectomyMyectomy– MypoplastyMypoplasty– MyorrhaphyMyorrhaphy

Treatment Procedures of the Treatment Procedures of the Muscular SystemMuscular System

TendonTendon– Carpal tunnel releaseCarpal tunnel release– TenectomyTenectomy– TenodesisTenodesis– TenolysisTenolysis– TenonectomyTenonectomy– TenotomyTenotomy– TenoplastyTenoplasty– TenorrhaphyTenorrhaphy

Proud of your Muscles?Proud of your Muscles?