The muscular system

MUSCULAR SYSTEM

MTHOBISI SHABANGU

INTRODUCTION• The muscular system is composed of specialized

cells called muscle fibers.

• These fibers are different lengths and shapes and

form to become muscles.

• Muscles make up about 42% of a person’s total

body weight.

• Muscle fibers are held together by connective

tissue , enclosed in “fascia”.

• Muscles must have proper oxygen and nutrition to

function properly.

TYPES OF MUSCLE TISSUEMuscle Tissue

SkeletalVoluntary

Satiated cells

SmoothInvoluntary

Blood vessels, Urinary bladder,Digestive system

TYPES OF MUSCLE TISSUES CONT…• Skeletal muscle

• Smooth Muscle

• Cardiac Muscle

Skeletal Muscle • How many

different muscles can there be?

• ~660

CHARACTERISTICS OF MUSCLES• Contractility – the ability of muscles to

shorten

• Elasticity – the ability of muscles to go back to its original shape

• Excitability – the ability of muscles to respond to stimuli

• Extensibility – the ability of muscle to lengthen

• Sphincter – muscles that constrict openings

CLASSIFICATION OF MUSCLES

FUNCTIONALLY

• Voluntary – can be moved at will

• Involuntary – can’t be moved intentionally

STRUCTURALLY

• Striated – have stripes across the fibers

• Smooth – no striations

CATEGORIES OF SKELETAL MUSCLE ACTIONSCATEGORIES

• Extensor

• Flexor

• Abductor

• Adductor

• Levator

• Depressor

• Rotator

• Sphincter

ACTIONS

• Increases the angle at a joint

• Decreases the angle at a joint

• Moves limb away from midline of body

• Moves limb toward midline of body

• Moves insertion upward

• Moves insertion downward

• Rotates a bone along its axis

• Constricts an opening

NAMING SKELETAL MUSCLES

• Shape:

• deltoid (triangle)

• trapezius (trapezoid, 2 parallel sides)

• serratus (saw-toothed)

• rhomboideus (rhomboid, 4 parallel sides)

• orbicularis and sphincters (circular)

Rhomboideusmajor

Trapezius

Deltoid

Serratus anterior

• Maximus (largest)

• minims (smallest)

• Longus (longest)

• Brevis (short)

• Major (large)

• Minor (small)

Psoas major

Psoas minor

MUSCLES NAMED BY SIZE

• Biceps (2)

• Triceps (3)

• Quadriceps (4)

MUSCLES NAMED FOR NUMBER OF ORIGINS

Biceps brachii

MUSCLES NAMED FOR ACTION

• Flexor carpi radialis (extensor carpi radialis)

– flexes wrist

• Abductor pollicis brevis (adductor pollicis)

– flexes thumb

• Abductor magnus – abducts thigh

• Extensor digitorum – extends fingers

Adductor magnus

COVERINGS OF SKELETAL MUSCLE

• Epimysium

• Connective tissue that covers the entire

muscle

• Lies deep to fascia

• Perimysium

• Surrounds organized bundles of muscle

fibers, called fascicles

• Endomysium

• Connective tissue that covers individual

muscle fibers (cells)

SARCOMERENow let us take a look at Sarcomere:

• A sarcomere is the functional unit of skeletal

muscle

• A sarcomere is the area between adjacent

Z-lines.

• During a muscle contraction the z-lines move

together and the sarcomere shortens.

Picture of a Sarcomere

Type I slow fibers of skeletal muscle

Type II fast fibers of skeletal muscle

Intermediate fibers of skeletal muscle

Slow tonic specially designed for postural muscles, red in colour due to high concentration of myoglobin and rich in mitochondria and oxidative enzymes

Fast tonic contractions needed for body movement, pale colour rich in glycogen and phosphorylases

Varient of Type II

Highly resistance to fatigue due to well-developed in aerobic respiration

Easily fatigue Resistant to fatigue

The types of Fibers

THERE ARE ABOUT 60 MUSCLES IN THE FACE.

Smiling is easier than frowning.

It takes 20 muscles to smile and over 40 to frown.

Smile and make someone happy.

MACROSTRUCTURE

Skeletal muscle c.s. 40x

It is the number of muscle fibers packed into a given muscle cross-sectional area that determine overall force-generating capacity

MICROSTRUCTURE

• basic functional unit of muscle

• Striated (light & dark bands)

• Contains ACTIN & MYOSIN filaments that are responsible for contraction

REFERENCES Dimapilis, H. 2014. Muscular System. www.slideshare.net/hansdimapilis/muscular-systemidsn Accessed 05/03/2014

Agamez, M. 2011. An overview comparing the three different types of muscular tissue. http://www.slideshare.net/monica_agamez/muscular-system. Accessed on the 05/03/2014

Marydelaney, L. 2009, Muscular System. http://www.slideshare.net/marydelaney/chapter-22-muscular-system. Accessed 05/03/2014

By Itsebo, 2011. The muscular-system. http://www.slideshare.net/itsebo/the-muscularsystempowerpoint-dr-bantiles Accessed 05/03/2014

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Cerny, L. 2009. Applied Excecise Physiology, Muscular Skeletal. http://www.slideshare.net/pcerny/muscular-system Accessed 05/03/2014