Download MUSCULAR SYSTEM

MUSCULAR SYSTEM
Muscles make up 50-60% of body wt.
More than 650 muscles in the body.
Each muscle is made of thousands of
muscle fibers ~ the size of a fiber optic
filament.
It takes 17 muscles to smile & 42 to frown.
The hardest working muscle is the heart.
The largest
muscle is the
Gluteus
Maximus.
The longest
muscle is the
Sartorius.
The strongest
muscle is the
Masseter
The prefix myo- & mys- means muscle
& the prefix sarco- means flesh so if
you hear these prefixes you’ll know
we’re talking about muscles.
Muscle Functions
1. Create skeletal movement by
contracting & relaxing.
2. control of organ & vessel size
3. maintain posture & position
4. support soft tissue
5. guard entrances and exits
6. maintain body temperature (85%)
7. Only body tissue that can shorten
(contract)
C. 3 Kinds of Muscle Tissue
1. Skeletal
– Striated
– Voluntary
– Stacked in Sheets
AKA: Somatic
Tissue
-Multinucleated
-Found attached to
skeleton
C. 3 Kinds of Muscle Tissue
2. Cardiac aka: heart muscle
#Branched cells w/Single
nuclei per cell.
#Thick striations called
Intercalated discs that
#Involuntary
#Cells are fused so when one
cell contracts, they all
contract, creating the
heartbeat.
C. 3 Kinds of Muscle Tissue
3. Smooth aka: Visceral
– Spindle shaped
– Nonstriated
– Involuntary
-Found around hollow organs such as
arteries, esophagus, stomach
D. Muscle Characteristics
1. Contractility
Ability to shorten and
exert tension or force
2. Excitability
Ability to respond to
stimuli
3. Extensibility
Ability to contract after
being stretched
4. Elasticity
Ability to regain initial
length after contraction
I. Overview
E. Each muscle is an organ comprised of:
1. Muscle tissue (smooth, cardiac,
or skeletal)
2. Connective tissues
3. Nervous tissue
4. Blood
II. Anatomy of Skeletal Muscle
A.Connective
Tissue
1. Superficial
Fascia: Fibrous
connective
tissue
surrounding &
separating
each
muscle
A. Connective Tissue
2. Deep
a. Epimysium – a tough
outer coat of connective
tissue surrounding the
entire muscle.
b. Perimysium - several
sheathed muslce fibers
wraped in a coarse fibrous
membrane.
A. Connective Tissue
2. Deep
c. Fascicles – a bundle of
perimysium muscle fibers.
d. Endomysium - a delicate
connective sheath around a
single muscle fiber
A. Connective Tissue
3. Tendons – cord like dense
fibrous connective tissue.
a. Formed from the union of
all three deep fascia
b. Connect muscle to
muscle or muscle to bone
A. Connective Tissue
4. Aponeurosis – flat sheet of
connective tissue that
indirectly attaches muscles
to bones, cartilage or other
muscles.
Aponeurosis
B. Muscle Fibers
1. Each muscle fiber
a. is a single, long, cylindrical muscle cell.
• Sarcolemma is the plasma membrane
of a muscle cell.
• Sarcoplasm is the cytoplasm of a
muscle cell.
• Many mitochondria
• Nuclei
• Sarcoplasmic reticulum
B. Muscle Fibers
1. Each muscle fiber
b. is wrapped in endomysium
1. Each muscle fiber
c. is a bundle of myofibrils which
is made of a budle of
myofilaments
B. Muscle Fibers
2. Fascicles:
a. a bundle of
muscle
fibers
b. wrapped in
perimysium
B. Muscle Fibers
3. Myofibrils
a. made of thin and thick
filaments
B. Muscle Fibers
3. Myofibrils
b. Thick filaments made up of
the protein myosin.
c. Thin filaments are made up
of the protein actin.
Thick filaments
Thin filaments
Tropomyosin and troponin are regulatory proteins
Actin and myosin are contractile proteins.
B. Muscle Fibers
3. Myofibril
d. Together, the thick and
thin filaments make up the
striations
B. Muscle Fibers
4. Sarcomeres- chains of tiny
contractile myofibrils
a. Contractile unit of a muscle
b. Consists of overlapping thick
and thin filaments
Sarcomere
B. Muscle Fibers
4. Sarcomere
c. Muscle contraction
results from thick and thin
filaments sliding past one
another.
C. Neuromuscular Junction
1. Where the
neuron and
muscle fiber
meet
2.The neuron and muscle fibers
it controls make up a motor
unit (2-2000 fibers/unit)
MOTOR UNIT
C. Neuromuscular Junction
3. When
stimulated, all
of the muscle
fibers of a
motor unit
contract all at once.
C. Neuromuscular Junction
4. Anatomy
Axon terminal – nerve end
• Produces a neurotransmitter
- acetycholine (Ach)
C. Neuromuscular Junction
4. Anatomy
Motor end
plate –
site on
muscle
with
Motor
end plate
acetycholine receptors
Synaptic cleft - space between
the nerve & motor end plate
III. Skeletal Muscle Contraction
A. Initiation events
1. nerve impulse
2. ACh released
3. Ach binds to
receptor on
muscle
4. Enzyme
(Acetylcholine
esterase
removes ACh
III. Skeletal Muscle Contraction
B. Action Potential
1. ACh causes to Na+ to diffuse
into cell
2. If threshold is reached, action
potential occurs
- impulse travels along
membrane resulting in
contraction
III. Skeletal Muscle Contraction
C. Sliding Filament Theory
1.Action potential causes Ca++
release from S.R
2.Ca++ binds to thin filament
3.Thin filament rotates exposing
binding site for myosin
4.Myosin binds actin
» uses ATP to "rachet" once
» releases, "and binds to next
actin
Calcium is the "switch" that turns
muscle "on and off" (contracting and
relaxing).
III. Skeletal Muscle Contraction
D. How Neurotoxins Work
1.cobra toxin and curare
– block Ach receptors
– cause flaccid paralysis, potentially
fatal respiratory arrest
2.nerve gas and insecticides
• inhibit AchE
• cause potentially fatal paralytic
convulsions
How a Nerve Gas Works
Normal
Nerve Gas
Effect of Atropine on the
Transmission of Acetylcholine in the
presence of a nerve agent
III. Skeletal Muscle Contraction
D. How Neurotoxins Work
3.Botulism toxin and curare
– block Ach release
– cause flaccid paralysis, potentially
fatal respiratory arrest
4.Tetanus toxin
• cause excessive Ach release from
motor neurons
• causes potentially fatal paralytic
convulsions (“lock jaw”)
III. Skeletal Muscle Contraction
E. Rigor Mortis
•
•
•
•
Ca++ pumps run out of ATP
Ca++ cannot be removed
continuous contraction
eventually tissues break down
IV. Energy Metabolism in Sk.Ms.
A. Aerobic Respiration
1.Most efficient use of glucose
Sources of glucose include blood
glucose and stored glycogen
2.36ATP/glucose
3.requires oxygen
4.occurs in mitochondria
– Muscle cells have more
mitochondria than any other cell
– Require a steady supply of O2
B. Creatine-phosphagen system
1.During rest, muscles store
energy as creatine
phosphokinase (CPK or CK)
2.During intense exercise, ATP
is depleted first, then CK is
used to convert ADP back to
ATP
C. Lactic Acid Pathway
1.Anaerobic use of glucose
2.2 ATP/ glucose
3.Lactic acid produced as waste
product – Oxygen Debt
– Is toxic to tissue
– Can be recycled in liver
V. Muscle Twitch
-cycle of contraction and
relaxation
V. Muscle Twitch
-cycle of contraction and
relaxation
A. Reasons for varying degrees
1. The number of muscle fibers
innervated by a single neuron
varies
2. Some motor units have lower
thresholds than others
3. Muscle fibers differ functionally:
fast twitch – slow twitch fibers
V. Muscle Twitch
B. Fast vs Slow Twitch Fibers
1. Differ in
– How they make ATP
– Speed of ATP break down
– Mitochondria content
– How fast they fatigue
B. Fast vs Slow Twitch Fibers
2. Slow Twitch Fibers
–
–
–
–
–
–
Smallest fibers
Fatigue resistant
Aerobic ATP production
Many mitochondria
Slow contractions
Example: uroanal muscles
B. Fast vs Slow Twitch Fibers
2. Oxidative Fast Twitch Fibers
FOG
–
–
–
–
–
Fatigue resistant
Aerobic ATP production
Many mitochondria
Fast contractions
Example: arm muscles
B. Fast vs Slow Twitch Fibers
3. Glycolytic Fast Twitch Fibers
– Largest fibers
– Fatigue easily
– Anaerobic ATP production
– Few mitochondria
– Strong fast contractions
– Example: sprinter’s leg muscles
B. Fast vs Slow Twitch Fibers
4. Muscles have combination of all
three fibers
– The number of each type varies
from individual to individual
Endurance running - slow and fast
oxidative fibers
Sprints - fast oxidative fibers and some
fast glycolytic fibers
Powerlifting - fast glycolytic fibers &
some fast oxidative
Old age - increase in slow oxidative
fibers
B. Fast vs Slow Twitch Fibers
4. Muscles have combination of
all three fibers
– Training/conditioning can
change the predominant fiber
type in muscles
Anabolic steroids
– similar to testosterone
– large doses required for good
effect
– Side effects:
– overall - kidney and heart damage,
aggressiveness
– females - sterility, facial hair,
breast & uterine atrophy
– males - baldness, atrophy of testis
Sports injuries - RICE therapy
– Rest
– Ice
– Compression
– Elevation
V. Skeletal Muscle
A. Muslce Attachments
1.Origin – attachment site of a muscle or
tendon to a bone that doesn’t move
during contraction.
2.Insertion – is the attachment site of a
muscle or tendon to a moving bone that
moves during a contraction. (usually distal)
V. Skeletal Muscle
B. Lever Systems
1.lever - rod that moves at the
fulcrum (fixed point)
2.fulcrum typically the joint moving
3.Resistance - gravity pulling on
body
4.Effort - muscle contraction
V. Skeletal Muscle
B. Lever Systems
4. Movement
occurs when
E > R
– First class
levers - E F R
V. Skeletal Muscle
B. Lever Systems
4. Movement
occurs when
E > R
– 2nd class
levers – F R E
Levers that operate @ a
mechanical disadvantage are fast
levers that require the muscles to
exert more force than the
resistance to be moved.
V. Skeletal Muscle
B. Lever Systems
4. Movement
occurs when
E > R
– 3rd class
levers – F E R
most common
Levers that operate @ a mechanical
advantage allow a large load to be moved
over a relatively small distance but
require relatively little effort
Interactions of Skeletal Muscles
• Skeletal muscles work
together or in opposition
• Muscles only pull (never
push)
• As muscles shorten, the
insertion generally
moves toward the origin
• Whatever a muscle (or
group of muscles) does,
another muscle (or group)
“undoes”
V. Skeletal Muscle Interactions
C. Muscle Groups
1.Many muscles are required
for any given movement
– 1 muscle moves arm up
– another muscle moves arm
down
C. Muscle Groups
2. Muscles work
together
– Agonist
> Prime move
> muscle that causes a movement
– Antagonist
> opposes the muscle that stretches;
regulates the muscle contraction
Ex. Arm flexion
Biceps – Agonist (prime mover)
Triceps -- Antagonist
Uncurl arm -- roles are reversed
C. Muscle Groups
2. Muscles work
together
– Synergist
>Assists the prime mover
– Fixator
>auxiliary muscles that steady a
movement (immobilizes a bone or muscle’s origin)
The Belly of a muscle is called the
Gaster!
Muscle Naming
1. Location of the muscle ex. Anterior tibialis,
ASIS, supra=above, infra=below,& sub=underneath
2. Size of the muscle ex. Maximus=largest,
minimis=smallest, vastus=huge, longus=long,
brevis=short, major=large, & minor=small
3. Direction of muscle fibers ex. Oblique (slant)
Rectus (straight)
4. Number of origins ex. Triceps=3 origins or
biceps=2 origins.
Muscle Naming
5. Location of origin & insertion ex. Sternocleidomastoid
sterno=sternum, cleiodo=clavicle, mastoid=location on the temporal
bone (mastiod bone)
6. Action of the muscle ex. Flexor= shortens angle b/w 2 bones,
Extensor= increases the angle b/w 2 bones, Depressor = lowers,
abductor= moves away from the midline, levator – lifts a structure
7. Shape of the muscle ex. Trapezius, Rhomboids,
deltoid=triangular, Latissimus=wide, teres=round, trapezius=trapezoid,
serratus=saw-tooth, & orbicularis=circular
 Remember there are always exceptions to every rule & some muscle do not obey this
naming rule.
Types of Body Movements
• Flexion – movement that decreases the angle b/w 2
bones. Seen in hinge joints & ball & socket joints.
• Extension– movement that increases the angle b/w
2 bones. If extension is greater than 180o it’s called
hyperextension.
• Abduction – Movement away from the midline of
the body.
Types of Body Movements
• Adduction – Movement toward the midline of the
body.
• Rotation – Movement where 1 bone moves around
the longitudinal axis of another bone. Common
movement in ball & socket joints.
• Circumduction – a combination movement of
flexion, extension, abduction & adduction. The
proximal end of a bone is stationary while the distal
end moves in a circle. Common in ball & socket
joints.
Types of Body Movements
• Dorsiflexion – movement of foot decreases the
angle b/w the foot & the tibia. (upward movement of the
foot – take your foot off the gas) Dorsiflexion in the foot is
comparable to extension of the hand @ the wrist.
• Plantarflexion – movement of the foot to increase
the angle b/w the foot & the tibia. (downward movement
of the foot – mash on the gas) Plantarflexion of the foot is
comparable to flexion of the hand @ the wrist.
Types of Body Movements
• Inversion – movement of the foot/ankle causing the
sole of the foot to turn inward, (internal rotation).
• Eversion – movement of the foot/ankle causing the
sole of the foot to turn outward, (external rotation)
• Pronation – movement causing the palm of the
hand to turn down.
Types of Body Movements
• Supination – movement causing the palm of the
hand to turn upward. (your hands are in supination
when standing in anatomical position)
• Opposition – move the thumb to touch to tips of the
opposite finger tips of the same hand.
• Protraction – movement of a body part anteriorly.
forward motion (jutting out) of a limb.
• Retraction – movement of a body part posteriorly.
backward motion of a limb.
Types of Body Movements
• Elevation – upward movement of a body part.
• Depression – downward movement of a body
part.
Types of Body Movements
Types of Body Movements
Types of Body Movements
Joint Motions
Arrangement of Muscle Fibers
• Convergent – fascicles converge from a broad origin to a single
tendon insertion (e.g., pectoralis major)
• Circular – fascicles are arranged in concentric rings (e.g.,
orbicularis oris)
Arrangement of Muscle Fibers
• Parallel – fibers run parallel to the long axis of the muscle (e.g.,
sartorius)
• Pennate (uni, bi, or multi)– short fascicles that attach obliquely to a
central tendon running the length of the muscle (e.g., rectus
femoris)
Major Skeletal
Muscles:
Anterior View
Figure 10.4b
Major Skeletal
Muscles:
Posterior View
Figure 10.5b
Muscle Functions of the Head & Neck
• Frontalis: Elevates the eyebrow; wrinkles forehead
horizontally.
• Orbicularis Oculi: Closes the eyelids; causes
squinting, winking & blinking.
• Orbicularis Oris: Draws lips together; pucker &
kissing muscle.
• Zygomaticus: Raises corner of mouth laterally as
in smiling or laughing.
• Buccinator: Compresses the cheek to hold food
during chewing, sucking in cheeks & allows to
blow a horn.
Muscle Functions of the Head & Neck
• Platysma: Depresses corner of mouth; Frowning,
pouting; tightens neck muscles when shaving.
• Masseter: Raises mandible & draws it forward=
Chewing
• Occipitalis: Draws scalp backward.
• Temporalis: Raises mandible. Covers temporal
bone in head.
• Mentalis: wrinkles chin.
• Sternocleidomastoid: Flexes head & bends it
laterally.
Muscles of the Scalp, Face, and Neck
Figure 10.6
Functions of Ventral Muscles of the Torso
• Pectoralis Major: Adducts, flexes & rotates
the humerus medially. Moves arm forward
across chest. (adduction)
• Pectoralis Minor: Draws scapula forward &
downward.
• Serratus Anterior: draws scapula forward
(protraction), upward rotation of the
shoulder girdle.
• External Intercostals: chest muscles that
elevate ribs & enlarge thorax during
breathing.
Ventral Torso Muscles
Muscles of Respiration
Figure 10.10a
Functions of Ventral Muscles of the Torso
• Internal Intercostals: Draw adjacent ribs
together.
• Diaphragm: Expands thorax; compresses contents
of abdominal cavity. (breathing)
• Rectus Abdominus: The major muscles for spine
/trunk flexion (aka: your 6pack)
• External Oblique: Slanted muscles of the abdomen
that flex & rotate the trunk (aka: you love handles)
• Internal Oblique: flexion of the trunk, lateral
flexion (same side), rotation (same side) of the trunk.
• Transverse Abdominis: compresses the
abdominal/pelvic cavity.
Muscles of the Abdominal Wall
Figure 10.11a
Functions of Dorsal Muscles of the Torso
• Trapezius: Hyperextension of head; adducts
scapula; raises scapula. Allows you to shrug your
shoulder & look up.
• Rhomboids Major & Minor: (beneath the trap) Small
rectangular muscles that square the shoulders iow:
Adducts & downward rotation of the shoulder.
• Latissimus Dorsi: A large muscle that adducts &
extends the shoulder. (muscle originates from the lumbodorsal fascia)
• Teres Major & Minor: External rotation &
horizontal abduction of the arm.
Functions of Dorsal Muscles of the Torso
• Erector Spinae: Primary back extensor, runs the length of the spine.
Also causes lateral trunk flexion & rotation of the head, neck,
shoulder, chest, & arm muscles. Made up of three columns on each
side of the vertebrae – iliocostalis, longissimus, and spinalis. Lateral
bending of the back is accomplished by unilateral contraction of
these muscles
• Lumbar Aponeurosis: Sheet like tendinous expansion of a muscle.
• Levator Scapulae: Extension of the neck, downward rotation &
elevation of the scapula. Synergist to the trapezius.
Dorsal Muscles of the Torso
Muscle Functions of the Upper Extremity
Shoulder:
• Anterior Deltoid: Abducts, flexes, internally
rotates & horizontally adducts the arm. (deltoid is the
antagonist to the trapezius)
• Medial Deltoid: Abducts the arm
• Posterior Deltoid: Abducts, extends, externally
rotates & horizontally abducts the arm.
• Coracobrachialis: flexes & horizontally adducts the
arm
Muscles Crossing the Shoulder
Posterior view
Figure 10.14a
Muscle Functions of the Upper Extremity
ROTATOR CUFF: SITS
• Supraspinatus; abducts the upper arm.
• Infraspinatus : Externally rotations the upper arm
• Teres Minor: Externally rotates the upper arm.
• Subscapularis : Internally rotations the upper arm.
Posterior view
Muscle Functions of the Upper Extremity
Muscles of the Arm
• Biceps brachii: Flexion of the elbow & shoulder &
supination of the forearm.
• Brachialis: Flexes the elbow.
• Pronator teres: Pronates the forearm.
• Triceps brachii: Extends the elbow, adducts &
extends the shoulder. (antagonist to biceps brachii)
• Anconeus: Elbow extension
Muscles Crossing the Shoulder
Anterior view
Posterior view
Muscle Functions of the Upper Extremity
Muscles of the Arm
• Supinator: supinates the forearm.
• Flexor carpi radialis: Flexes & abducts the wrist.
• Flexor carpi ulnaris: Flexes & adducts the wrist.
• Extensor carpi radialis longus: Extends & adducts
the wrist.
• Extensor digitorum (longus & brevis): Extends
the wrist.
Superficial Dorsal view
Deep Dorsal view
Muscle Functions of the Hand
There are three groups of intrinsic hand muscles:
• The thenar eminence (ball of the thumb)
• The hypothenar eminence (ball of the little finger)
– both have a flexor, an abductor, and an
opponens (opposer)muscle
• The midpalm muscles, the lumbricals and
interossei, extend the fingers
• The interossei also abduct and adduct the fingers
Superficial Dorsal view
Deep Dorsal view
Muscle Functions of the Hand
• Flexor digitorum Longus & brevis: flexes the fingers.
• Extensor digitorum longus & brevis: extends the Fingers.
• Extensor Pollicus Longus & Brevis: extends the thumb.
• Abductor Pollicus Longus & Brevis: abducts the thumb.
• Adductor Pollicus Longus & Brevis: adducts the thumb.
• Flexor Pollicus Longus & Brevis: flexes the thumb.
Muscle Functions of the Lower Extremity
Muscles of the Quadriceps (primary knee extensors)
• Rectus femoris: hip flexion & knee extension
• Vastus Lateralis & Medialis: knee extension.
• Vastus Intermedius: knee extension
Other Muscles of the Thigh
• Sartorius: flexion, external rotation & abduction of the hip; Flexion
& internal rotation of the knee
• Gracilis: Abduction, flexion & internal rotation of the hip; Internal
rotation of the knee.
• Adductor longus: Adduction, flexion & horizontal adduction of
the hip. Allows you to grip a horse’s back w/your legs.
• Adductor magnus: Adduction, flexion & horizontal adduction of
the hip.
Muscles of the Pelvis & Femur
Muscle Functions of the Lower Extremity
Muscles of the Posterior Thigh:
• Semimembranosus: Extension of the hip; Flexion
& internal rotation of the knee.
• Semitendinosus: Extension & internal rotation of
the hip; Flexion & internal rotation of the knee.
• Biceps Femoris: Extension of the hip; External
rotation & flexion of the knee.
•
Muscle Functions of the Lower Extremity
Muscles of the Posterior Thigh:
• Gluteus Maximus: Extension, external rotation,
horizontal abduction & adduction of the hip.
Used to extend the hip when climbing stairs; forms
the buttox.
• Gluteus Medius & Minimus: abduction, horizontal
abduction & internal rotation of the hip.
Muscle Functions of the Lower Extremity
Muscles of the lower leg:
• Tibialis Anterior: Dorsiflexion & inversion of the
foot.
• Extensor Digitorum Longus: Dorsiflexion &
eversion of the foot.
• Extensor Hallicus Longus: inversion & extension
of the big toe.
• Peroneus (Fibularis) Longus & Brevis: Plantarflexion &
eversion of the foot.
Muscle Functions of the Lower Extremity
Muscles of the lower leg:
• Soleus: plantarflexion of the foot. (lower calf muscle)
• Gastrocnemius: Plantarflexion of the foot &
flexion of the knee. (upper calf muscle)
• Triceps Surae is the combination of the Soleus & the Gastronemius. Aka: toe
dancer’s muscle.
• Abductor Hallicus Longus & Brevis: abducts the
big toe.
• Adductor Hallicus Longus & Brevis: adducts the
big toe.
• Flexor Hallicus Longus & Brevis: flexes the big
toe.
Muscles of the
Lower Leg
Figure 10.22a
Muscle Functions of the Lower Extremity
Muscles of the lower leg:
• Flexor digitorum Longus & brevis: flexes the toes.
• Extensor digitorum longus & brevis: extends the
toes.
• Extensor Hallicus Longus & Brevis: extends the
big toe.
Muscles of the
Anterior Lower
Leg
Figure 10.21a
References
http://images.google.com/images?svnum=10&hl=en&lr=&ie=U
TF-8&oe=UTF-8&q=fascia++epimysium&spell=1
\
http://www.mhhe.com/biosci/ap/holeessentials/student/olc/graph
ics/hole06ehap_s/other/chap08outline.doc
http://fitness.freewebspace.com/muscles%20and%20their%20m
ovements.htm