MUSCLES

Chapter 8“We are made wise not by the recollection of our past, but the

responsibility for our future.”George Bernard Shaw

SMOOTH MUSCLES

Smooth – Hollow organs, blood vessels, and respiratory passages

Involuntary Causes wavelike contractions = peristalsis Look like a toothpick Uni-nucleate Triggers: nerve impulse, hormonal

stimulation, stretching and more

CARDIAC MUSCLES

Found only in heart Involuntary Intercalated disc Uni-nucleate Striated Triggers: self-excitatory; nerves and/or

hormones influence rate

SKELETAL MUSCLE

MUSCLE FIBERS ARE CIGAR SHAPEDMULTINUCLEATE LARGEST OF MUSCLE FIBER TYPESSTRIATEDVOLUNTARY MOVES SKELETAL SYSTEM Triggers: nerve system

MUSCLE FUNCTIONS

PRODUCES MOVEMENT• SKELETAL – WALKING, LIFTING

• SMOOTH – BLOOD & FOOD MOVEMENT

• CARDIAC – PUMPS BLOOD

MAINTAINS POSTURE STABILIZES JOINTS GENERATES HEAT One neuron & all its muscle fibers = one motor unit

MUSCLE COMPOSITION

Muscle fiber has cell wall called sarcolemma The sarcolemma is insulated by ENDOMYSIUM Many groups of endomysium wrapped fibers are

grouped together, wrapped in PERIMYSIUM and called a FASCICLE.

Many fasicles are wrapped together by EPIMYSIUM EPIMYSIUM COVERS ENTIRE MUSCLE &

CONTINUES DOWN TO MERGE INTO A TENDON OR SPREAD INTO AN APONEUROSES

NEUROMUSCULAR JUNCTION

Impulse from nerve caused a release of neurotransmitter (acetylcholine – ACh) via vesicle to exocytose to synaptic cleft.

ACh diffuses across cleft to receptors on muscle sarcolemma at the motor end plate.

Muscle must be excitable to begin the action potential

MUSCLE CONTRACTION

Must be able to shorten and change its shape The sarcolemma is filled with MYOFIBRILS

(organelles of the cell) Each MYOFIBRIL has bands, giving it a

striped look The bands are actin and myosin filaments.

They are the contractile unit of the sarcomere.

FROM SMALLEST TO LARGESTA REVIEW……..

ACTIN & MYOSIN (MICROFILAMENTS) make up a sarcomere

Many SARCOMERE make a MYOFIBRIL Many myofibrils are in a cell; the cell wall is

called a SARCOLEMMA Sarcolemma are covered by ENDOMYSIUM Several endomysium covered sarcolemma

are wrapped by PERIMYSIUM to make a FASCICLE

CONTINUED

Many fasicles are wrapped together by EPIMYSIUM The epimysium wrapped package of fibers is a

muscle; biceps, triceps, spinator EPIMYSIUM merges into a tough cord called a

TENDON to connect the biceps to its insertion site EPIMYSIUM may spread to become an

APONEUOSIS (SHEET) which attaches the muscle to a bone surface.

BANDING OF SARCOMERE

BARE ZONE = NO ACTIN PRESENT AT RELAXATION

DARK AREA = THICK FILAMENT CALLED MYOSIN

THIN FILAMENT CALLED ACTIN

HOW A CONTRACTION HAPPENS

The presence of ACH at the muscle receptor causes a change in polarity. The change in Na and K balance causes the ACTION POTENTIAL

Once started, the stimulus is unstoppable and travels the length of the sarcolemma.

The action potential stimulates the sarcoplasmic reticulum to RELEASE CALCIUM into the cytoplasm

CALCIUM triggers the opening of the myosin binding site on the actin filaments by binding to tropinin and tropomyosin.

You Tube Assistance Nerve at Synapse

http://www.bing.com/videos/search?q=Action+Potential+Animation+McGraw+Hill&Form=VQFRVP#view=detail&mid=BD481F1B29FC2BF8421DBD481F1B29FC2BF8421D

Muscle http://www.bing.com/videos/search?q=YouTube+Muscle+Contraction&FORM=RESTAB#view=detail&mid=27DFE0C5623BB0825B6327DFE0C5623BB0825B63

CONTINUED

The cross-bridge heads attach to the open site. The attachment and release of cross bridges to

actin causes a “rowing motion” of the myosin heads pulling the actin filament closer together resulting in a contraction.

During the muscle contraction, Acetylcholinesterase breaks down ACH to stop the influx of ions across the sarcolemma

CONTINUED

THE CELL RETURNS TO RESTING STATE AS THE SODIUM- POTASSIUM PUMP RETURNS THE IONS TO ORIGINAL CONCENTRATION

What kind of movement is this called? THE ACETYLCHOLINESTERASE HAS

NEGATED THE NERVE IMPULSE UNTIL THE NEXT NEUROTRANSMITTER RELEASE IS ACHIEVED

ENERGY FOR CONTRACTIONS

MUSCLES STORE VERY LITTLE ATP IT’S GONE IN SECONDS!!! NEXT, IT LOOKS FOR CREATINE

PHOSPHATE IN MUSCLES TAKES A PHOSPHORUS MOLECULE

TO RE-ENERGIZE ADP TO ATP USES ALL CP WITHIN 20 SECONDS!!!

AEROBIC RESPIRATION

OCCURS IN MITOCHONDRIA GLUCOSE BROKEN DOWN INTO H2O

& CO2 RELEASING ENERGY ENERGY CAPTURED AS ATP GET 36 ATP FOR 1 GLUCOSE SLOW; NEEDS O2 (FROM

MYOGLOBIN) & NUTRIENT FUELS IN CONTINUOUS FLOW

ANAEROBIC GLYCOLYSIS

OCCURS IN CYTOSOL GLUCOSE BECOMES PYRUVIC ACID &

ENERGY 2 ATP FOR 1 GLUCOSE PYRUVIC ACID & OXYGEN = ENERGY PYRUVIC ACID & NO O2 = LACTIC ACID FASTER; BUT PROMOTES MUSCLE

FATIGUE & SORENESS

MUSCLE FATIGUE

FATIGUE = UNABLE TO CONTRACT EVEN THOUGH STIMULATED

CONTRACTION BECOMES WEAKER UNTIL STOPS

USUALLY DUE TO O2 DEBT OF PROLONGED MUSCLE ACTIVITY

CAN HAPPEN TO MARATHON RUNNERS

O2 DEBT MUST BE PAID BACK

EFFECTS OF EXERCISE ON MUSCLES

USE IT OR LOSE IT!!!!!!! EXERCISE INCREASES SIZE, STRENGTH

& ENDURANCE AEROBIC EXERCISE = INCREASED

RESISTANCE TO FATIGUE, IMPROVES METABOLISM & DIGESTION, INCREASES COORDINATION, MAKES SKELETON STRONGER, LUNGS MORE EFFICIENT, CLEANS FAT DEPOSITS FROM BLOOD VESSEL WALLS

ISOTONIC CONTRACTIONS

SAME TONE OR TENSION BENDING KNEE SMILING MOVEMENT OCCURS

ISOMETRIC CONTRACTION

SAME MEASUREMENT INCREASES THE TENSION ON THE

MUSCLE NO MOVEMENT MUSCLES vs IMMOVABLE OBJECT

RESISTANCE EXERCISES

BODY BUILDERS USE THIS MAKING MUSCLES CONTRACT WITH

AS FORCE AS POSSIBLE ENLARGES THE MUSCLE CELL

USE ISOTONIC FOR HEALTH USE ISOMETRIC FOR DEFINITION OF

MUSCLES

MUSCLE TONE

SOME MUSCLE FIBERS ARE ALWAYS CONTRACTING EVEN WHEN WE ARE RELAXED

MAKES MUSCLE FEEL FIRM CONTINUOUS PARTIAL

CONTRACTIONS = MUSCLE TONE

MOVEMENT NAMES

FLEXION – DECREASE ANGLE OF JOINT EXTENSION – ENLARGES ANGLE ROTATION – MOVING BONE AROUND

LONGITUDINAL AXIS ABDUCTION – AWAY FROM MIDLINE ADDUCTION – TOWARD MIDLINE CIRCUMDUCTION – PROXIMAL END IT

STABLE, DISTAL END MOVES IN A CIRCLE

SPECIAL MOVEMENTS

DORSIFLEXION – STAND ON HEELS PLANTAR FLEXION – POINT TOES INVERSION – TURN SOLE MEDIALLY EVERSION – TURN SOLE LATERALLY SUPINATION – PALM FACES ANTERIORLY PRONATION – PALM FACES DORSALLY OPPOSITION – THUMBS TO FINGER TIPS

INTERACTIONS of MUSCLES

PRIME MOVER – MAJOR MUSCLE CAUSING MOVEMENT

ANTAGONIST- REVERSES MOVEMENT OF PRIME MOVER

SYNERGISTS – HELPS PRIME MOVER OR STABILIZES JOINT

FIXATORS – STABILIZE ORIGIN OF PRIME MOVER OR HOLDS BONE STILL

NAMING MUSCLES

DIRECTION OF THE FIBERS SIZE OF MUSCLE LOCATION NUMBER OF ORIGINS SHAPE ACTION LOCATION OF ORIGIN & INSERTION

ARRANGEMENT OF FASCICLES

CIRCULAR – SPHINCTERS CONVERGENT – MEET IN ONE SPOT PARALLEL – EVEN TO LONG AXIS

• FUSIFORM – LIKE PARALLEL WITH WIDE CENTER

PENNATE- FEATHERLIKE PATTERN, ENTERS THE TENDON• UNIPENNATE, BIPENNATE, MULTIPENNATE

FACIAL MUSCLES

FRONTALIS ORBICULARIS OCULI ORBICULARIS ORIS BUCCINATOR ZYGOMATICUS CHEWING MUSCLES

• MASSETER

• TEMPORALIS

NECK MUSCLES

PLATYSMA – SHEET OF MUSCLE FROM CHEST TO MANDIBLE- PULLS CORNER OF MOUTH DOWN = SAG

STERNOCLEIDOMASTOID – COME FROM STERNUM AND CLAVICLE TO INSERT ON MASTOID

ANTERIOR TRUNK MUSCLES

PECTORALIS MAJOR INTERCOSTALS ABDOMINAL GIRDLE

• RECTUS ABDOMINUS – STRAIGHT FROM PUBIS TO RIB CAGE

• EXTERNAL OBLIQUE – SIDES TO CENTER DOWNWARD

• INTERNAL OBLIQUE – SIDES TO CENTER UP

• TRANSVERSE ABDOMINUS – LOWER RIBS AND ILIAC CREST ACROSS ABDOMEN

POSTERIOR MUSCLES

TRAPEZIUS – TRIANGULAR IN UPPER BACK

LATISSIMUS DORSI – LOWER BACK ERECTOR SPINAE – ALONG SPINE DELTOID – TRIANGULAR IN

SHOULDER/ UPPER ARM

MUSCLES CAUSING HIP MOVEMENT

GLUTEUS MAXIMUS – FORMS BUTTOCKS, HIP EXTENSOR

GLUTEUS MEDIUS – HIP ABDUCTOR, STEADIES PELVIS DURING WALKING

ILIOSPOAS – HIP FLEXOR, PREVENTS HYPEREXTENSION

ADDUCTOR MUSCLE – ADDUCT HIP

MUSCLES & KNEE JOINTS

HAMSTRING GROUP – POSTERIOR THIGH, HAVE LARGE TENDON BY KNEE

SARTORIUS - WEAK THIGH FLEXOR; SYNERGISTICS TO SIT LIKE AN INDIAN

QUADRICEPS – • RECTUS FEMORIS – EXTENDS KNEE & FLEX HIP

• 3 VASTUS MUSCLES – HELP EXTEND KNEE

MUSCLES AND ANKLE/ FOOT

GASTROCNEMIUS IS MOST IDENTIFIABLE AS THE CALF MUSCLE

CAUSES PLANTAR FLEXION OF FOOT AND FLEXES THE KNEE

DEVELOPMENTAL ASPECTS OF MUSCLES

MUSCULAR DYSTROPHY – MUSCLES ENLARGE DUE TO FAT & CONNECTIVE TISSUE DEPOSITS BUT THE MUSCLE FIBERS ARE DEGENERATING • DUSCHENNE’S MD – DX BY AGE 2-6

• W/C BY 10 -12

• DEATH IN YOUNG ADULTHOOD

CONTINUED

MYASTHENIA GRAVIS – A SHORTAGE OF ACH RECEPTORS AT NEURO- MUSCULAR JUNCTION DUE TO ANTIBODIES AT RECEPTOR SITES. MUSCLE CELLS HAVE POOR STIMULATION & WEAKEN. DEATH RESULTS FROM RESPIRATORY FAILURE.

AGING

LOSE MUSCLE MASS AND STRENGTH AS WE AGE UNLESS WE EXERCISE TO KEEP FIRM

LOSE 50% OF STRENGTH BY AGE 80

DISORDERS OF ASSOCIATED STRUCTURES

BURSITIS TENDONITIS BUNIONS TENOSYNOVITIS SHINSPLINTS CARPAL TUNNEL SYNDROME

MEDICAL TERMINOLOGY

PLEASE KNOW THE TERMS ON PAGES 181 AND 182