the muscular system presentation by dr nazia

The Muscular SystemThe Muscular System 11

The Muscular SystemThe Muscular System

By:

Dr. Nazia Qamar

Lecturer Anatomy

LCMD


Muscles:contractile tissueMuscles:contractile tissueMuscles are Muscles are responsible for all types responsible for all types of body movementof body movementThree basic muscle Three basic muscle types are found in the types are found in the bodybody

–Skeletal muscleSkeletal muscle–Cardiac muscleCardiac muscle–Smooth muscleSmooth muscle


Characteristics of MusclesCharacteristics of MusclesMuscle cells are elongated Muscle cells are elongated (muscle cell = muscle fiber)(muscle cell = muscle fiber)

Contraction of muscles is Contraction of muscles is due to the movement of due to the movement of microfilamentsmicrofilaments

All muscles share some All muscles share some terminologyterminology– Prefix Prefix myomyo refers to muscle refers to muscle– Prefix Prefix mysmys refers to muscle refers to muscle– Prefix Prefix sarcosarco refers to flesh refers to flesh


Skeletal Muscle CharacteristicsSkeletal Muscle Characteristics

Most are Most are attached by attached by tendons to tendons to bonesbones


Skeletal Muscle CharacteristicsSkeletal Muscle CharacteristicsCells are multinucleateCells are multinucleate

StriatedStriated – have visible banding – have visible banding

VoluntaryVoluntary – subject to conscious control – subject to conscious control

Cells are surrounded and bundled by Cells are surrounded and bundled by connective tissueconnective tissue


How to study skeletal muscles:

origo, insertion, position (scheme,

tables), identification, muscle groups,

innervation, function,

osteofascial spaces (compartments),

transverse sections of limb segments,

dissection

How to study skeletal muscles


Attachments of skeletal muscles – origin, insertion,

endomysial and perimysial sheaths, fascia

perimysiumendomysiumepimysium

Connective tissue wrapping of skeletal muscle


muscle fibre,

myofibrils,

sarcomeres

sarcoplasmic

reticulum,

T-tubules,

triads

mitochondria,

sarcolemma,

basal lamina

Microscopic anatomy of skeletal muscle


Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

SarcomereSarcomere– Contractile unit of a muscle fiberContractile unit of a muscle fiber


Smooth Muscle CharacteristicsSmooth Muscle CharacteristicsHas no striationsHas no striations

Spindle-shaped Spindle-shaped cellscells

Single nucleusSingle nucleus

Involuntary – no Involuntary – no conscious controlconscious control

Found mainly in Found mainly in the walls of hollow the walls of hollow organsorgans


Cardiac Muscle CharacteristicsCardiac Muscle CharacteristicsHas striationsHas striations

Usually has a Usually has a single nucleussingle nucleus

Joined to another Joined to another muscle cell at an muscle cell at an intercalated discintercalated disc

InvoluntaryInvoluntary

Found only in the Found only in the heartheart


Function of MusclesFunction of MusclesProduce Produce movementmovement

Maintain postureMaintain posture

Stabilize jointsStabilize joints

Generate heatGenerate heat


• Type 1 fibres are slow-contracting and fatigue-resistant

• Type 2A fibres are fast-contracting and easily fatigue

• Type 2X fibres are fast-contracting and resistant to fatigue

Fibre Types of Skeletal Muscle


Fascicular architecture of muscles

pennation of muscles


Shapes of muscle fibersShapes of muscle fibers


Properties of Skeletal Muscle Properties of Skeletal Muscle ActivityActivity

Irritability – ability to Irritability – ability to receive and respond to a receive and respond to a stimulusstimulus

Contractility – ability to Contractility – ability to shorten when an shorten when an adequate stimulus is adequate stimulus is receivedreceived


Naming Skeletal Muscles

Action

Origin&

Insertion

ShapeNumber

OfOrigins

Size

Location

Direction ofMuscleFibers

SkeletalMuscle


Direction of Muscle FibersRelative to the MidlineRECTUS = parallel to the midline– Rectus

Abdominus

TRANSVERSE = perpendicular to midline


LocationStructure near which muscle is found– FRONTALIS = near

FRONTAL bone– OCCIPITALIS =

near OCCIPITAL bone


SizeRelative Size of MuscleMAXIMUS = largest– Gluteus Maximus

MEDIUS = middle– Gluteus Medius

MINIMUS = smallest– Gluteus Minimus

LONGUS = longest– Fibularis Longus

BREVIS = short– Fibularis Brevis

TERTIUS = shortest– Fibularis Tertius


Number of OriginsNumber of tendons of originBICEPS = Two– Biceps Brachii

Biceps FemorisTRICEPS = Three– Triceps Brachii

QUADRICEPS = Four– Quadriceps Femoris– Transverse Abdominus

OBLIQUE = diagonal to midline– External Oblique


ShapeRelative Shape of the MuscleDELTOID = triangular shape ΔTRAPEZIUS = trapezoid shape SERRATUS = saw-toothed ♒RHOMBOIDEUS = rhomboid shape TERES = round ○


Origin & InsertionOrigin – attachment to an immoveable boneInsertion – attachment to a movable boneILIO COSTALIS= attaches to the ilium & ribs (costal = ribs)


ActionNAME ACTION EXAMPLE

FLEXOR Decrease angle at a joint Flexor Carpi Radialis

EXTENSOR Increase angle at a jointExtensor Carpi Ulnaris

ABDUCTOR Move bone away from midline

Abductor Pollicis Longus

ADDUCTOR Move bone toward midline Adductor Longus

LEVATOR Produce upward movement Levator Scapulae

DEPRESSOR Produce downward movement

Depressor Labii Inferioris

SUPINATOR Turn palm upward/anterior Supinator

PRONATOR Turn palm downward/posterior Pronator Teres


Nerve supply of skeletal muscle

Innervation of skeletal muscle: motoneurons, motor units,

motor end- plates, acetylcholine, proprioceptive neurons,


Types of MusclesTypes of MusclesPrime mover – muscle with the major Prime mover – muscle with the major responsibility for a certain movementresponsibility for a certain movement

Antagonist – muscle that opposes or Antagonist – muscle that opposes or reverses a prime moverreverses a prime mover

Synergist – muscle that aids a prime Synergist – muscle that aids a prime mover in a movement and helps prevent mover in a movement and helps prevent rotationrotation

Fixator – stabilizes the origin of a prime Fixator – stabilizes the origin of a prime movermover


Muscular DystrophyMuscular DystrophyCongenital muscle-destroying disease Congenital muscle-destroying disease affect specific muscle groupsaffect specific muscle groups

Muscle fibers degenerate & atrophy due Muscle fibers degenerate & atrophy due to an absence of dystrophin, a protein to an absence of dystrophin, a protein that helps keep muscle cells intactthat helps keep muscle cells intact

Most common & serious—Duchenne’s Most common & serious—Duchenne’s M.D.M.D.– Mostly in males Mostly in males (diagnosed between2-6 yrs)(diagnosed between2-6 yrs)– Survival is rare beyond early 30’sSurvival is rare beyond early 30’s– X-linked recessiveX-linked recessive


Myasthenia gravisMyasthenia gravisRare adult disease caused by Rare adult disease caused by antibodies to acetylcholine antibodies to acetylcholine receptors at the neuromuscular receptors at the neuromuscular junction which prevents the junction which prevents the muscle contraction from muscle contraction from occurring occurring

Drooping upper eyelids, Drooping upper eyelids, difficulty swallowing & talking, difficulty swallowing & talking, muscle weakness & fatiguemuscle weakness & fatigue

Death occurs when respiratory Death occurs when respiratory muscles cease to functionmuscles cease to function


AgingAgingConnective Tissue Connective Tissue increasesincreases

Amount of Muscle tissue Amount of Muscle tissue decreasesdecreases

Muscles become Muscles become stringier(sinewy)stringier(sinewy)

Body weight declines due Body weight declines due to loss of muscle massto loss of muscle mass

By age 80, muscle strength By age 80, muscle strength usually decrease by 50% usually decrease by 50% without weight training without weight training exercisesexercises


Effects of Exercise on MuscleEffects of Exercise on MuscleAerobics result in stronger Aerobics result in stronger muscles due to increase muscles due to increase blood supply blood supply

Muscle fibers increase Muscle fibers increase mitochondria and oxygen mitochondria and oxygen storage storage Muscle becomes more fatigue resistant

Heart enlarges to pumpHeart enlarges to pump

more blood to bodymore blood to body

Does not increase skeletal Does not increase skeletal

muscle sizemuscle size


Results of increased Results of increased muscle use from muscle use from resistance trainingresistance training

Individual muscle Individual muscle cells make more cells make more contractile filaments contractile filaments & connective tissue & connective tissue increasesincreases– Increase in muscle sizeIncrease in muscle size– Increase in muscle Increase in muscle

strengthstrength

Effects of Exercise on MuscleEffects of Exercise on Muscle


Five Golden Rules of Gross Five Golden Rules of Gross Muscle ActivityMuscle Activity

1.1. all muscles cross at least one jointall muscles cross at least one joint

2.2. bulk of muscles lies proximal to the bulk of muscles lies proximal to the joint crossedjoint crossed

3.3. all muscles have at least 2 all muscles have at least 2 attachments: origin & insertionattachments: origin & insertion

4.4. muscles only pull/never pushmuscles only pull/never push

5.5. during contraction the muscle during contraction the muscle insertion moves toward the origininsertion moves toward the origin


THANK YOU

the muscular system presentation by dr nazia

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