Download Muscle Tissue & Muscular System

Muscular System
 Muscle Tissue
 The Muscular System
Muscle Tissue
Introduction
Skeletal Muscle Tissue
& The Muscular System
Anatomy of Skeletal
Muscle
Contraction of Skeletal
Muscle
Muscle Mechanics
Muscle Tissue
Aging & the Muscular
System
Integration With Other
Systems
Cardiac Muscle Tissue
Smooth Muscle Tissue
Introduction
• Importance to body function
• Importance to human activity
• Active & passive forces
Learning Objectives
• Importance:
 Discuss the central role of muscle
tissue in a variety of human
activities and necessary body
functions
• Active Forces:
 Compare & contrast tension,
compression, & resistance
Importance:
Function & Activity
• Human activity
 gross movements of the body
 communication
speaking
facial expression & gestures
• Body function




circulation
respiration
digestion
reproduction
Body Movement
Communication
Bodily Functions
Active & Passive
Forces
• Resistance
 passive force opposing movement
 dependent on weight, shape, friction, etc
• Tension
 active force applied to an object to produce
movement
 when applied tension > resistance, object is
pulled toward source of tension
• Compression
(not assoc. w/ muscle movement)
 active force applied to an object to produce
movement
 when applied compression > resistance, object is
pushed away from source of compression
Muscle Contraction
Produces Tension
RESISTANCE
TENSION
Skeletal Muscle Tissue
& The Muscular System
• Tissue characteristics
• Functions of muscle tissue
Learning Objectives
• Characteristics & Functions:
 Describe the characteristics &
functions of muscle tissue
Muscle Tissue
• One of 4 primary tissue types of the
body
• Types of muscle tissue
 skeletal
 cardiac
 smooth
• Body muscles are organs
that contain skeletal muscle tissue,
connective tissues, nerves, epithelial
tissue & smooth muscle tissue (in
blood vessels)
Muscle Tissue Types
skeletal muscle
smooth muscle
cardiac muscle
Functions of
Skeletal Muscle Tissue
• Produce skeletal movement
• Maintain posture & body
position
• Support soft tissues
• Guard entrances into & exists
out of the body
• Maintain body temperature
Mr. G
Before he got
married
Anatomy of
Skeletal Muscle
• Connective tissue organization
• Blood vessels & nerves
• Microanatomy of skeletal
muscle fibers
Learning Objectives
• Tissue Structure:
 Describe the organization of
muscle at the tissue level
• Cellular Structure:
 Explain the unique characteristics
of skeletal muscle fibers
• Organelle Structure:
 Identify the structural components
of a sarcomere
Connective Tissue
Organization
• Surrounding Sheaths
– Epimysium
– Perimysium
– Endomysium
• Tendons
Connective Tissue
Organization
• Epimysium
 outer connective tissue layer
dense layer of collagen fibers
deep fascia
 surrounds entire muscle
• Perimysium
 middle connective tissue layer
collagen & elastic fibers
contains blood vessels & nerves
 surrounds fascicles: dividing
muscle into compartments
Connective Tissue
Organization
• Endomysium
 inner connective tissue layer
delicate c.t.
 surrounds muscle fibers & satellite
cells
satellite cells (stem cells)
Connective Tissue
Organization
 Epimysium, perimysium, &
endomysium unite at muscle ends to
form:
• Tendons –
linear bundle attaching muscle to
bone
• Aponeuroses –
broad sheet attaching muscle to
bone [same function as “tendon”]
Connective
AnimationTissue
Organization
Blood Vessels
& Nerves
blood vessels
nerve
Microanatomy
• Organelles of Skeletal Muscle
Fibers
• Sarcomere Organization
• Microfilament Structure
Microanatomy of
Skeletal Muscle Fibers
• Muscle fiber: muscle cell
 long, thin (among largest cells in body)
 multinucleate – peripheral, oval
nuclei
• Sarcolemma: cell membrane
 openings for penetrating tubules
 established membrane potential
due to Na-K ion exchange pumps
Microanatomy of
Skeletal Muscle Fibers
• Sarcoplasm: cytoplasm
 contains contractile proteins
 contains numerous mitochondria
• Sarcoplasmic reticulum (SR):
endoplasmic reticulum
 terminal cisternae – fused SR
tubules
 triads – regions where T tubules &
SR cisternae contact
Microanatomy of
Skeletal Muscle Fibers
• Transverse tubules: T tubules
 continuous w/ sarcolemma
 network throughout cell
 close contact w/ SR
• Myofibrils
 100s-1000s of bundles of
myofilaments
thin filaments
thick filaments
Microanatomy of
Skeletal Muscle Fibers
• Sarcomere




repeating units in myofibrils
linked end-to-end
functional unit of a muscle fiber
components
thick protein filaments
thin protein filaments
proteins stabilizing thick & thin
filaments
proteins regulating interaction btw/
thin & thick filaments
Sarcomere
Organization
• Banded appearance due to
overlap of thick & thin filaments
 A bands – appear dark
 I bands – appear light
• A band – contains thick & thin
filaments
 M line
center of sarcomere
thick filaments only - connected by
stabilizing protein
Sarcomere
Organization
• A band
(cont)
 H zones
lateral to M line
thick filaments only
 Zones of overlap
lateral to H zones
thick & thin filaments overlap
Sarcomere
Organization
• I bands – contain thin filaments only
 edges of sarcomere
• Z lines
 boundaries btw/ adjacent
sarcomeres
 protein complexes attached to thin
filaments
Note A & I bands &
peripheral nuclei
Sarcomere Organization
A
I
Functional Organization
Thin Filaments
• Composition (proteins)
 F actin
twisted filament of G actin globular
proteins
contains active sites that can bind to
thick filaments
 tropomyosin
protein cover over active sites of F actin
 troponin
binds tropomyosin to active site
contains Ca2+ receptor
Thin Filaments
• Troponin-tropomyosin complex
 reacts to bound Ca2+ by uncovering
active sites on F actin of thin
filament
 necessary for contraction
Thick Filaments
• Composition (protein)
 myosin
subunits – tail & head
 tail –
binds to other myosin molecules
 head –
projects outward toward thin
filament
called cross-bridges
Thick & Thin
Filament Structure
Contraction
Of Skeletal Muscle
• The control of skeletal muscle
activity
• Relaxation
• The contraction cycle
• Length-tension relationships
Learning Objectives
• Neuromuscular Junction:
 Identify the components of the
neuromuscular junction &
summarize the events involved in
the neural control of skeletal
muscle function
• Muscle Cell Contraction:
 Explain the key steps involved in
the contraction of a skeletal
muscle fiber
Control of Skeletal
Muscle Activity
• Neuromuscular junction
 neural axon branch terminates w/
synaptic terminal at every muscle
fiber
 synaptic terminal – contains
neurotransmitter acetylcholine
(ACh)
 synaptic cleft – separates terminal
from muscle fiber sarcolemma
Control of Skeletal
Muscle Activity
• Neuromuscular junction
 motor end plate – sarcolemma
surface w/ ACh receptors
 acetylcholinesterase (AChE) – in
cleft; breaks down ACh
• ACh receptors of motor end plate
bind to ACh released from synaptic
terminal and respond by opening
gated ion channels in sarcolemma
Membrane Potential:
Electrochemical Gradient
positive charge due to  [Na+]
negative charge due to
 [protein]  [a.a.]  [F.A.]
Neural Stimulation of
Muscle Fibers
Step 1. Arrival of action potential.
action potential – electric impulse
travels down axon of neuron
enters synaptic terminal of neuron
Step 2. Release of ACh.
exocytosis – synaptic vesicles
containing ACh fuse w/
neurolemma
ACh enters synaptic cleft
Neural Stimulation of
Muscle Fibers
Step 3. ACh binds at motor end
plate.
ACh diffuses across cleft & binds
to ACh receptors of sarcolemma
gated Na-channel proteins open &
sarcolemma becomes permeable
to Na+
Na+ floods into sarcoplasm
Neural Stimulation of
Muscle Fibers
Step 4. Appearance of action
potential in sarcolemma.
Na+ influx results in action
potential at motor end plate
action potential spreads across the
“excitable” sarcolemma & down T
tubules
action potential affects SR
Neural Stimulation of
Muscle Fibers
Step 5. Return to initial state.
AChE in cleft breaks down ACh
ACh unbinds from receptors
gated Na-channels close & Na+ is
pumped back out of sarcoplasm by
Na-K ion pumps
Steps 1 – 5
Contraction &
Relaxation
• Excitation-Contraction Coupling
 action potential impulses cause
release of Ca2+ from SR
 Ca2+ binds to F actin of myofibrils
to initiate sarcomere contraction
 continued reception of impulses
causes continued contraction
• Relaxation
 Ca2+ is reabsorbed by SR
 sarcomeres cease contraction
Sarcomere
Contraction Cycle
Step 1. Active site exposure.
Ca2+ released from SR binds to
troponin
troponin pulls tropomyosin away
from active site on F actin
Step 2. Cross-bridge attachment.
myosin heads (cross-bridges) bind
to exposed active sites of F actin
Sarcomere
Contraction Cycle
Step 3. Pivoting of myosin head.
 “cocked” myosin heads are bent away
from M line due to stored energy from
breakdown of ATP to ADP + Pi
 ADP & Pi remain bound to heads in
resting sarcomere
 attachment of myosin head to active site
of F actin releases stored energy to
create a power stroke of head toward M
line
 ADP & Pi are released as stroke occurs
Sarcomere
Contraction Cycle
Step 4. Cross-bridge detachment.
ATP binds to myosin head
following stroke
head unbinds from active site
exposed active site available for
binding to next myosin head along
length of myosin filament
Sarcomere
Contraction Cycle
Step 5. Myosin reactivation.
ATP  ADP + Pi
released energy “recockes” myosin
head
 Cycle can now be repeated under
conditions:
  [Ca2+] maintained
  [ATP] maintained
Observations of Sarcomere
During Muscle Contraction
sliding filament theory
Sarcomere Contraction
• To View Video:
– Move mouse cursor over slide titlelink
– When hand appears, click once
• MOV Video plays about 3-1/4 min
Additional Animation
Muscle Mechanics
• Tension production
• Energetics of muscular activity
• Muscle performance
Learning Objectives
• Muscle Contraction:
 Explain the all-or-nothing principle
of muscle contraction
 Discuss the structure & function
of a motor unit
 Distinguish between isotonic &
isometric contraction
• Energetics:
 Describe the mechanisms by
which muscle fibers obtain the
energy to power contractions
Muscle Contraction:
Tension Production
• All-or-None Principle
 muscle fibers are either
stimulated to the point of
contraction or not
 once stimulated, the entire
muscle fiber contracts
• Tension produced by whole
skeletal muscle due to:
1) frequency of stimulation
2) # of fibers stimulated w/in muscle
Muscle Contraction:
Motor Unit
• Motor unit
 A single motor neuron & all the
muscle fibers controlled by it
• Motor unit size
 4-6 fibers in eye muscles – provide
precise control of movement
 1000-2000 in leg muscles – provide
less precise control
Muscle Contraction:
Motor Unit
• Recruitment
 Smooth, steady increase in the number
of motor units involved in a muscle
contraction
 a.k.a., multiple motor unit summation
• Muscle tone
 some motor units w/in a muscle are
always active
 switch off w/ resting units regularly to
distribute activity
Isotonic Muscle
Contraction
• Isotonic contraction
Tension plateaus & muscle changes length
 concentric contraction
– tension > resistance: muscle shortens
ex: lifting weight
 eccentric contraction
– peak tension < resistance: muscle
elongates due to contraction of another
muscle or gravity
ex: lowering weight
Isometric Muscle
Contraction
• Isometric contraction
 tension varies but does not
overcome resistance
 muscle does not shorten
 Note: individual muscle fibers
shorten until tendons are taught &
external tension = internal tension
generated by fibers
ex: holding a weight stationary;
pushing against an immovable object
Charles
Atlas
Muscle Relaxation: Return
to Resting Length
Causes of muscle relaxation:
• Recoil of stretched elastic fibers in
perimyzium
• Contractions of opposing muscles
• Gravity
Energetics
of Muscle Activity
• ATP is produced by cellular
respiration in muscle fibers
• At rest, excess ATP energy stored as
creatine phosphate (CP)
ATP + creatine 
ADP + creatine phosphate
Energetics
of Muscle Activity
• During contraction myosin crossbridges beak down ATP to ADP + Pi
• Energy stored as creatine phosphate
(CP) “recharges” ADP
ADP + creatine phosphate
 ATP + creatine
Aerobic Energy
Metabolism : O2 Present
• Glycolysis
 in cytosol of cytoplasm
 C6H12O6  2 pyruvate
 yields 2 ATP (net)
• Aerobic cellular respiration
 in mitochondria
 2 pyruvate + 6O2  6CO2 + 6H2O
 yields 25-34 ATP
Storage Compounds
O=O
glycogen stores glucose
myoglobin stores O2
Anaerobic Energy
Metabolism: O2 Absent
• Glycolysis
 in cytosol of cytoplasm
 C6H12O6  2 pyruvate
 yields 2 ATP (net)
• Lactic acid fermentation
 in cytosol
 2 pyruvate  2 lactic acid
 yields 0 ATP
Muscle
Muscle Activity:
Activity:
Resting
Moderate
Strenuous
Learning Objectives
• Fiber Types:
 Relate the types of muscle fibers
to muscle performance
• Aerobic & Anaerobic
Endurance:
 Distinguish between aerobic &
anaerobic endurance & explain
their implications for muscle
performance
Fiber Types: Fast
• Fast twitch muscle fibers





contract w/in 0.01 sec after stimulation
large diameter
densely packed myofibrils
reserves:  glycogen; ↓ myoglobin
few mitochondria
• Powerful contraction w/ rapid fatigue
 deplete ATP reserves rapidly
 activity supported by anaerobic
metabolism
• Pale reddish color
Fiber Types: Slow
• Slow twitch muscle fibers





contract w/in 0.03 sec after stimulation
small diameter
fewer myofibrils
reserves:  myoglobin;  lipid; ↓ glycogen
many mitochondria
• Moderate contraction w/ slow fatigue
 deplete ATP reserves more slowly
 activity supported by aerobic metabolism
• Dark reddish color
Fiber Types:
Intermediate
• Intermediate muscle fibers
 properties intermediate btw/ fast twitch
& slow twitch
• Pale reddish color
Note:
 Human muscles contain mixtures of
3 types
 Content varies w/ genetics & use
Muscle Size
• Hypertrophy
 increase in muscle mass
 # muscle fibers constant
 diameter of muscle fibers 
• Atrophy
 decrease in muscle mass
 # muscle fibers constant
 diameter of muscle fibers 
Anaerobic Endurance
• Length of time muscular
contraction can continue
supported by glycolysis &
existing reserves of ATP & CP
• Limited by
 Amount of ATP & CP on hand
 Amount of available glycogen
 ability of muscle to tolerate lactic
acid
Anaerobic Endurance
• Training regimen
 Frequent, shortduration
exercise w/
intensive levels
of muscular
activity
 Ex: sprinting;
speed swimming;
weight lifting;
basketball
Aerobic Endurance
• Length of time muscular
contraction can continue
supported by mitochondrial
activity
• Limited by
 Amount of substrates from
breakdown of carbohydrates, fatty
acids, &/or amino acids
 Amount of available oxygen
Aerobic Endurance
• Training regimen
 Sustained, long
duration
exercise w/ low
levels of
muscular activity
 Ex: jogging;
cross country
running; distance
swimming; dance
movements
Aging &
The Muscular System
• Effects of aging on the body’s
skeletal muscles
• Effect of life style on aging of
muscles
Learning Objectives
• Aging:
 Specify 4 effects of aging on
muscles
 Discuss how regular exercise
early in life can counter the
effects of aging on the
muscular system
Effects of Aging
• Skeletal muscle fibers decrease in
diameter
–  in myofibrils
• Skeletal muscles lose elasticity
– fibrosis  collagen content
• Tolerance for exercise decreases
–  thermoregulatory ability
–  rate of fatigue
• Ability to recover from muscular injuries
decreases
– # satellite cells 
–  collagen content
Life Style & Aging
• Rate of decline in muscle
performance is same for all
individuals regardless of exercise
patterns or lifestyle
• To be in good shape late in life ……
you must be in very good shape early
in life
• Regular, moderate exercise is more
important than extremely demanding
exercise
Integration With Other
Systems
• Dependence on other body
systems
• Responses of body systems to
muscular activity
Learning Objectives
• Integration:
 Discuss the interaction &
responses of 5 specific body
systems to muscular activity
Integration: Support From
Other Body Systems
• Cardiovascular System
  heart rate & dilation of blood vessels
cause
 O2 delivery & CO2 removal
transports heat to skin for radiation to
environment
• Respiratory System
  respiratory rate & depth of respiration
 O2 delivery & CO2 removal
• Integumentary System
 dilation of blood vessels &  sweating
removes excess heat that would interfere w/
muscle protein activity
Integration: Support From
Other Body Systems
• Nervous System
 controls voluntary muscle contraction
 regulates/coordinates cardiovascular,
respiratory, & integumentary system
activities
• Endocrine System
 regulates/coordinates cardiovascular,
respiratory, & integumentary system
activities
 maintains [Ca2+] & [-PO43-] in blood &
other body fluids via skeletal, digestive,
& urinary systems
Integration: Bones,
Joints, & Muscles
• To View Video:
– Move mouse cursor over slide titlelink
– When hand appears, click once
• ASX Video plays about 24 min
• A Video Quiz is included in the
presentation
Cardiac
Muscle Tissue
• Structural differences between
cardiac & skeletal muscle
tissues
• Functional differences between
cardiac & skeletal muscle
tissues
• The role of cardiac muscle in
the body
Learning Objectives
• Structure & Function:
 Identify the structural &
functional differences between
cardiac muscle tissue & the
other types of muscle tissue
 Discuss the role that cardiac
muscle plays in the
cardiovascular system
Cardiocytes:
Structural Organization
•
•
•
•
•
•
•
Single nucleus
Branched cellular structure
Striated – myofibrils & sarcomeres
T tubules – short & broad; no triads
SR – no terminal cisternae
Mitochondria –  #
Intercalated discs – btw/ adjacent
cells; transfer contractions from one
cell to several others
instantaneously
Cardiocytes:
Functional Features
• Automaticity – contraction w/out
neural stimulation
– “pacemaker” cells
• Innervation – alters pace of
contraction
• Duration of contraction – 10 X longer
• Sarcolemma characteristics –
prevent summation & tetany
• Dependent on aerobic metabolism – 
# mitochondria &  [myoglobin]
Smooth
Muscle Tissue
• Structural differences between
smooth & skeletal muscle
tissues
• Functional differences between
smooth & skeletal muscle
tissues
• The role of smooth muscle in
body systems
Learning Objectives
• Structure & Function:
 Identify the structural & functional
differences between smooth
muscle tissue & the other types of
muscle tissue
 Discuss the role that smooth
muscle plays in various body
systems
Smooth Muscle Cells:
Structural Organization
• Single nucleus
• Spindle-shaped cellular structure
• Non-striated – no myofibrils or
sarcomeres; thick & thin filaments
scattered through cytoplasm
• Dense body network – attach to thin
filaments & to sarcolemma
• No T tubules
• SR – loose network
• Connective tissue sheaths – do not
unite to form tendons or aponeuroses
Smooth Muscle Cell:
Functional Features
• Excitation-Contraction coupling –
Ca2+ enter cell from extracellular
fluid & bind to calmodulin which
activates myosin light chain kinase
to break down ATP & initiate
contraction
• Plasticity – length-tension
relationship allows for variable
contraction length
Smooth Muscle Cell:
Functional Features
• Control of contraction – involuntary;
many cells not innervated; respond to
nearby smooth muscle cells
 multiunit smooth muscle cells –
connected to 1 or more motor neurons;
leisurely contraction
loci – iris of eye; ♂ reproductive tract; large
arteries; arrector pili muscles
smooth muscle sheet
 visceral smooth muscle cells –
many lack direct neural contact
loci – digestive tract; urinary & gall bladders;
many internal organs
The Muscular System
Introduction
Biomechanics &
Muscle Anatomy
Muscle Terminology
The Axial Muscles
The Appendicular
Muscles
Introduction
• Voluntary control
• Form & function
• Factors determining the effects
of contraction
Muscles
• To View Video:
– Move mouse cursor over slide titlelink
– When hand appears, click once
• ASX Video plays about 5 min
Learning Objectives
• Muscle Control:
 Relate the muscular system to nervous
control
• Muscle Shape:
 Discuss how the structure of a muscle
provides clues to its primary function
• Effects of Muscle Contraction:
 Discuss 2 factors that interact to
determine the effect of a muscle’s
contraction
Voluntary Muscles
• Muscular System
 All muscles controlled voluntarily
 700 identified
 20% studied in book
 ~ 30 studied for course
• Form & function
 locomotor muscles - stretch across
joints
 soft tissue support muscles - form sheets
or slings
 muscles guarding body entrances - form
rings
Voluntary Muscles
• Effects of contraction determined by
 anatomical arrangement of muscle fibers
 attachment points of muscle to bones
Biomechanics &
Muscle Anatomy
• Organization of skeletal muscle
fibers
• Skeletal muscle length-tension
relationships
• Levers
Learning Objectives
• Fascicles:
 Describe the arrangement of
fascicles in the various types of
muscles & explain the resulting
functional differences
• Levers:
 Describe the different classes of
levers & how they make muscles
more efficient
Organization of Skeletal
Muscle Fibers
• Fascicles
 bundles of muscle fibers w/in a
muscle
• Patterns of fascicle organization
 parallel muscles – fascicles parallel
to long axis of muscle
central body or belly w/ tendons at
ends (most muscles)
some w/ broad attachments –
aponeuroses
Ex: biceps brachii
Organization of Skeletal
Muscle Fibers
• Patterns of fascicle organization
 convergent muscles – fascicles begin
over a broad area & narrow to a
single tendon or tendinous sheet
 raphe – some attach to band of
collagen fibers
Ex: pectoralis major
Organization of Skeletal
Muscle Fibers
• Patterns of fascicle organization
 pennate muscles – fascicles form
common angle w/ tendon
feather-shaped
unipennate – all fascicles on same
side of tendon; Ex: tensor digitorum

bipennate – fascicles on both sides
of tendon; Ex: rectus femoris

multipennate – tendon & fascicles
branch; Ex: deltoid

Organization of Skeletal
Muscle Fibers
• Patterns of fascicle organization
 circular muscles – fascicles
concentrically arranged around
opening or recess
 contraction  decrease in diameter
Ex: orbicularis oris
Fascicle Arrangements
Length-Tension
Relationships
• Muscles develop maximum tension
over a narrow range of sarcomere
length
 stretched muscle – less overlap of thick
& thin filaments in sarcomere
 contracted muscle – normal thick-thin
filament relationship is disrupted
Ex: when curling weights flexion is harder to
achieve when arm muscles are stretched in
extended arm, becomes easier as muscles
contract, then harder after full flexion is
achieved
Length-Tension
Relationships
• During complex movement – muscles
work in groups
 smaller muscles aid larger muscles to
reach length where maximum tension
can be achieved
Levers
•
Lever – rigid structure that moves
on a fixed point called the fulcrum

•
In body, each bone is a lever; each joint
is a fulcrum
Lever action
1) change direction of an applied force
2) change distance & speed of movement
produced by applied force
3) change the effective strength of an
applied force
Classes of Levers
•
First-class - fulcrum btw/ AF & R
 like see-saw
Ex: muscles that extend neck
•
Second-class - R btw/ AF & fulcrum
 like loaded wheelbarrow
Ex: calf muscles during plantar flexion
•
Third-class - AF btw/ R & fulcrum
 opposite of 2nd-class
 most common lever action of body
Ex: biceps brachii during flexion
Muscle Terminology
• Origins & insertions
• Actions
• Names of skeletal muscles
• Divisions of the muscular
system
Learning Objectives
• Origins & Insertions:
 Predict the actions of a muscle on the
basis of the relative positions of its
origin & insertion
• Movements:
 Explain how muscles interact to produce
or oppose movements
• Muscle Names:
 Explain how the name of a muscle can
help identify its location, appearance,
and/or function
Origins & Insertions
• Origin
 beginning point of muscle
attachment
 usually remains stationary – bone
that moves little or not at all
 usually proximal on limb
• Insertion
 end point of muscle attachment
 usually moves – bone that moves
 usually distal on limb
Actions
• Actions include flexion,
extension, adduction, etc
• In terms of bone affected
 textbook ex: “flexion of the
forearm”
• In terms of joint affected
 professional ex: “flexion of the
elbow”
Primary Actions
• Agonist
– prime mover muscle chiefly
responsible for a movement
Ex: biceps brachii flexes elbow
• Antagonist
– prime mover muscle chiefly
responsible for the opposite
action of the agonist
Ex: triceps brachii extends elbow
Primary Actions
• Synergist
– assists action of prime mover
agonist or antagonist
 aid in action of prime mover
 fixator - stabilizes origin of prime
mover by preventing competing
movement at a joint
Naming Skeletal
Muscles
• Fascicle organization
 rectus = straight: fascicles parallel
to long axis of body
 transversus = across: fascicles
perpendicular to long axis of body
 obliquus = oblique: fascicles
angled to long axis of body
• Location
 brachii = arm
 femoris = thigh
Naming Skeletal
Muscles
• Relative position
 externus, extrinsic, superficialis = outer
body surface
 internus, intrinsic, profundus = beneath
the body surface
• Structure
 biceps = 2 tendons of origin
 quadriceps = 4 tendons of origin
• Shape
 deltoid = triangular
 orbicularis = circular
Naming Skeletal
Muscles
• Size & length
 longus & longissimus = long &
longest (respectively)
 vastus = large
 teres = long & round
 brevis = short
 magnus, major, & maximus = big,
bigger, & biggest (respectively)
 minor & minimus = smaller &
smallest (respectively)
Naming Skeletal
Muscles
• Position relative to body axis




anterior = front
posterior = back
lateralis = toward side
medialis = toward midline
• Origin & insertion
 sternohyoid = origin on sternum,
insertion on hyoid bone
Naming Skeletal
Muscles
• Action
flexor = causes flexion
extensor, tensor = causes extension
depressor = causes lowering of body part
buccinator = trumpeter (muscle that
purses lips)
 sartorius = tailor-like (muscle that allows
crossing of legs)




Muscular System
• Divisions of the Muscular
System
 axial musculature
positions head & spinal column
moves rib cage
60% of all muscles
 appendicular musculature
stabilizes & moves the arms & legs
40% of all muscles
Axial Muscles
• Muscles of the head & neck
• Muscles of the spine
• Oblique & rectus muscles
• Muscles of the pelvic floor
Learning Objectives
• Axial Muscles:
 Identify the principal axial muscles
of the body together with their
origins, insertions, actions, &
innervation
Muscles of the
Head & Neck
•
•
•
•
•
•
•
•
orbicularis oris
orbicularis oculi
oculomotor muscles
zygomaticus major & minor
buccinator
masseter
sternocleidomastoid
platysma
Muscles of the
Face
Oculomotor Muscles
Muscles of the
Torso
•
•
•
•
•
•
scalenes
external intercostals
internal intercostals
external oblique
rectus abdominis
diaphragm
Appendicular Muscles
• Muscles of the shoulders &
upper limbs
• Muscles of the lower limbs
• Musculoskeletal compartments
Learning Objectives
• Appendicular Muscles:
 Identify the principal appendicular
muscles of the body together with
their origins, insertions, actions, &
innervation
 Compare the major muscle groups
of the upper & lower limbs & relate
their differences to their functional
roles
Muscles of the
Shoulder
•
•
•
•
•
•
trapezius
serratus anterior
pectoralis minor
pectoralis major
latissimus dorsi
deltoid
Muscles of the
Upper Limb
•
•
•
•
•
triceps brachii
biceps brachii
brachioradialis
brachialis
extensor muscles (general
locus)
• flexor muscles (general locus)
Muscles of the
Anterior Thigh
•
•
•
•
•
•
rectus femoris
vastus lateralis
vastus medialis
vastus intermedius
sartorius
gracilis
quadriceps
femoris
Muscles of the
Anterior Thigh
Muscles of the
Lateral & Posterior Thigh
•
•
•
•
•
tensor fasciae latae
gluteus maximus
semitendinosis
biceps femoris
semimembranosis
hamstrings
Muscles of the
Lower Leg
• gastocnemius
– calcaneal tendon (Achilles tendon)
•
•
•
•
soleus
tibialis anterior
peroneus longus
peroneus brevis
Muscles of the
Anterior Lower Leg
Musculoskeletal
Compartments
Muscular System
Overview