The Muscular System by Group 5

5/20/2018 The Muscular System by Group 5

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MUSCULAR SYSTEM


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Did you know that ?

- more than 50% of body weight

is muscle !

- And muscle is made up of

proteins and water


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The Muscular System

Muscles are responsible for all movement

of the body

There are three basic types of muscle

Skeletal

Cardiac

Smooth


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Info About Muscles

Only body tissue able

to contract

create movement by

flexingand extending

joints

Body energy

converters (many

muscle cells contain

many mitochondria)


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3 Types of Muscles


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Three types of muscle

Skeletal Cardiac Smooth


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Classification of Muscle

Skeletal-

found in limbs

Cardiac-

found in heart

Smooth-

Found in

viscera

Striated, multi-

nucleated

Striated, 1

nucleus

Not striated, 1

nucleus

voluntary involuntary involuntary


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Characteristics of Muscle

Skeletal and smooth muscle are elongated

Muscle cell = muscle fiber

Contraction of a muscle is due to movement

of microfilaments(protein fibers)

All muscles share some terminology

Prefixes myoand mysrefer to muscle

Prefix sarcorefers to flesh


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Shapes of Muscles

Triangular-shoulder, neck

Spindle-arms, legsF lat-diaphragm, forehead

Circular-mouth, anus


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Skeletal Muscle

Most are attached by tendonsto bones

Cells have more than one nucleus

(multinucleated)

Striated-have stripes, banding

Voluntary-subject to conscious control

Tendons are mostly made of collagenfibers

Found in the limbs

Produce movement, maintain posture,

generate heat, stabilize joints


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Structure of skeletal muscle

Each cell (fibre) is long and cylindrical

Muscle fibres are multi-nucleated

Typically 50-60mm in diameter, and up

to 10cm long

The contractile elements of

skeletal muscle cells are

myofibrils


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Skeletal muscle - Summary

Voluntary movement

of skeletal parts

Spans joints andattached to skeleton

Multi-nucleated,

striated, cylindrical

fibres


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Smooth Muscle

No str iations

Spindleshaped

Singlenucleus

Involuntary-no conscious control

Found mainly in the walls of hollow organs


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Smooth muscle Lines walls of viscera

Found in longitudinal orcircular arrangement

Alternate contraction of

circular & longitudinalmuscle in the intestineleads to peristalsis


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Structure of smooth muscle

Spindle shaped uni-nucleated cells

Striations not observed

Actin and myosin filaments are present(

protein fibers)


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Smooth muscle - Summary

Found in walls of

hollow internal

organs

Involuntary

movement of

internal organs

Elongated, spindleshaped fibre with

single nucleus


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Cardiac Muscle

Str iations

Branchingcells

Involuntary

Found only in the heart

Usually has a single nucleus, but can havemore than one


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Cardiac muscle

Main muscle of heart

Pumping mass of heart

Critical in humans

Heart muscle cells

behave as one unit

Heart always contracts

to its full extent


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Structure of cardiac muscle

Cardiac muscle cells (fibres) areshort, branched and interconnected

Cells are striated & usually have 1

nucleus Adjacent cardiac cells are joined

via electrical synapses (gap

junctions) These gap junctions appear as

dark lines and are called

intercalated discs


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Cardiac muscle - Summary

Found in the heart

Involuntary rhythmic

contraction

Branched, striated

fibre with single

nucleus and

intercalated discs


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Muscle Control

Type of

muscle

Nervous

control

Type of

control

Example

SkeletalSkeletal Controlledby CNS Voluntary Lifting aglass

CardiacRegulated

by ANS

Involuntary Heart

beating

Smooth Controlled

by ANSInvoluntary Peristalsis


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Types of Responses

Twitch-

A single brief contraction

Not a normal muscle functionTetanus

One contraction immediately followed by

anotherMuscle never completely returns to a relaxed

state

Effects are compounded


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Where Does the Energy Come

From?

Energy is stored in the muscles in the form

of ATP

ATP comes from the breakdown of glucoseduring Cellular Respiration

This all happens in the Mitochondriaof the

cell When a muscle is fatigued(tired) it is

unable to contract because of lack of

Oxygen


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Exercise and Muscles

I sotonic-muscles shorten and movement

occurs ( most normal exercise)

I sometr ic-tension in muscles increases, nomovement occurs (pushing one hand against

the other)


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How are Muscles Attached to

Bone?

Origin-attachmentto a movable bone

I nsertion-attachment to an immovablebone

Muscles are always attached to at least 2

points Movement is attained due to a muscle

moving an attached bone


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Muscle Attachments

Origin

Insertion

T pes of M sc lo Skeletal Mo ement


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Flexion

Types of Musculo-Skeletal Movement


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Extension


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Hyperextension


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Abduction, Adduction &

Circumduction


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Rotation


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More Types of Movement

I nversion-turn sole of foot medially

Eversion-turn sole of foot laterally

Pronation-palm facing down

Supination-palm facing up

Opposition-thumb touches tips of fingers

on the same hand


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The Skeletal Muscles

There are about 650 muscles in the

human body. They enable us to

move, maintain posture and generate

heat. In this section we will onlystudy a sample of the major muscles.


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SternocleidomastoideusFlexes and Rotates Head


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MasseterElevate Mandible

li


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TemporalisElevate & Retract Mandible

i


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TrapeziusExtend Head, Adduct, Elevate or

Depress Scapula

L i i D i


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Latissimus DorsiExtend, Adduct & Rotate Arm Medially

D l id


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DeltoidAbduct, Flex & Extend Arm


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Pectoralis Major

Flexes, adducts & rotates arm medially

Bi B hii


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Biceps BrachiiFlexes Elbow Joint

T i B hii


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Triceps BrachiiExtend Elbow Joint

R t Abd i


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Rectus AbdominusFlexes Abdomen

E t l Obli


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External ObliqueCompress Abdomen

E t l I t t l


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External IntercostalsElevate ribs

I t l I t t l


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Internal IntercostalsDepress ribs

Di h


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DiaphragmInspiration


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Forearm Muscles

Flexor carpiFlexes wrist

Extensor carpiExtends wrist

Flexor digitorumFlexes fingers

Extensor digitorumExtends fingers

PronatorPronates

SupinatorSupinates

Gluteus Maximus


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Gluteus MaximusExtends & Rotates

Thigh Laterally

Rectus Femoris


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Rectus Femoris

Flexes Thigh,Extends Lower Leg

Gracilis


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GracilisAdducts and Flexes Thigh

Sartorius


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Sartorius

Flexes Thigh, &

Rotates ThighLaterally

Biceps Femoris


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Biceps Femoris

Extends Thigh &Flexes Lower Leg

Gastrocnemius


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Gastrocnemius

Plantar Flexes Foot

& Flex Lower Leg

Tibialis Anterior


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Tibialis AnteriorDorsiflexes and Inverts Foot

The Muscular System


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Documents

The Muscular System by Group 5