Download Muscular System

Muscular System
Chapter 8
8:1 Introduction
Three (3) Types of Muscle Tissues
• Skeletal Muscle
• Usually attached to bones
• Voluntary
• Striated
• Cardiac Muscle
• Wall of heart
• Involuntary
• Striated
• Smooth Muscle
• Walls of most viscera, blood vessels and skin
• Involuntary
• Not striated
Prefixes ____, _____, and ____ all refer to muscle
2

Skeletal muscle tissue
 Packaged into skeletal muscles
 ___________
 Longest of the muscle cell types
 Have stripes called striations
 __________ – subject to conscious control
 Contracts rapidly; however, tires easily and
must rest after short period of activity
 Origin/insertion
8.2: Structure of Skeletal Muscle
• Skeletal Muscle
• Organ of the muscular system
composed of:
• ____________
• ____________
• ___________
•____________
5
Connective Tissue Coverings
•
Fascia – _________
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Aponeuroses
•
Tendons – ____
•
Aponeuroses – _____
Skeletal muscles
Tendons
6
Connective Tissue Coverings
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• Muscle coverings:
• Epimysium –
___________ (blends with
Fascia)
• Perimysium – _______
•Endomysium –
___________(fasciculus)
within fascicle
Muscle
Bone
Fascicles
Tendon
Muscle fibers (cells)
Fascia
(covering muscle)
Epimysium
Perimysium
Myofibrils
Thick and thin filaments
Endomysium
Fascicle
Axon of motor
neuron
Blood vessel
Nucleus
Sarcoplasmic
reticulum
Myofibril
Filaments
Muscle fiber
Sarcolemma
5
7
Skeletal Muscle Fibers
• Myofibrils
– play role in
contraction
•Composed of thick and
thin protein myofilaments
• ________myofilaments (thin)
• _______ myofilaments (thick)
• _______ (functional unit of
muscle)
• Sarcoplasmic reticulum (SR)
• Transverse (‘T’) tubule
• Triad
• Cisternae of SR
• T tubule
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Myofibrils
Cisternae of
sarcoplasmic reticulum
Triad
Transverse tubule
Nucleus
Sarcoplasmic
reticulum
Openings into
transverse tubules
Mitochondria
Thick and thin
filaments
Sarcoplasm
Nucleus
Sarcolemma
8
Skeletal Muscle Fibers
Striation pattern
made by
arrangement of
myofilaments in
myofibrils
• I band (thin)
• A band (thick and
thin)
• H zone (thick)
• Z line (or disc)
• M line
• Sarcomere
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Skeletal muscle fiber
Sarcoplasmic
reticulum
Thick (myosin)
filaments
Thin (actin)
filaments
Myofibril
Sarcomere
Z line
I band
(a)
H zone
Z line
M line
A band
I band
A band
(b)
9
• Thin myofilaments
• Thick myofilaments
• Composed of myosin protein
• Form the cross-bridges
• Composed of actin protein
• Associated with troponin
and tropomyosin proteins
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Myosin “heads”
Troponin
Tropomyosin
Myosin
molecule
Thick
filament
Thin filament
Actin molecule
11
Neuromuscular Junction
• Synapse - __________
• Parts
• Motor neuron
• Motor end plate
• Synaptic cleft
• Synaptic vesicles
• Neurotransmitters
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Synaptic
vesicles
Mitochondria
Motor
neuron axon
Acetylcholine
Synaptic
cleft
Folded
sarcolemma
Axon branches
Muscle fiber
nucleus
(a)
Motor
end plate
Myofibril of
muscle fiber
12
8.3: Skeletal Muscle Contraction


Contraction results from a movement
within the myofibrils in which the actin and
myosin filaments slide past one another,
shortening the sarcomeres.
Muscle fiber shortens and pulls on its
attachments
14
Stimulus for Contraction
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• Acetylcholine (ACh)
• Nerve impulse causes release of
ACh from synaptic vesicles
• ACh binds to ACh receptors on
motor end plate
• Generates a muscle impulse
• Muscle impulse eventually
reaches the SR and the cisternae
Synaptic
vesicles
Mitochondria
Motor
neuron axon
Acetylcholine
Synaptic
cleft
Folded
sarcolemma
Axon branches
Muscle fiber
nucleus
(a)
Motor
end plate
Myofibril of
muscle fiber
15
Excitation-Contraction Coupling
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• Muscle impulses cause SR to
release calcium ions into cytosol
• _________ binds to troponin to
change its shape
• The position of ___________ is
altered
• Binding sites on actin are now
exposed
• Myosin heads bind to actin,
forming cross-bridges
•Page 194
Tropomyosin
Troponin
Thin filament
Actin monomers
ADP + P
ADP + P
Thick filament
1 Relaxed muscle
Ca+2
Ca+2
Muscle contraction
Release of Ca+2 from sarcoplasmic
reticulum exposes binding sites on
actin:
Muscle relaxation
Active transport of Ca+2 into sarcoplasmic
reticulum, which requires ATP, makes
myosin binding sites unavailable.
Ca+2 binds to troponin
ATP
Tropomyosin pulled aside
Binding sites on
actin exposed
Ca+2
ADP + P
Ca+2
ADP + P
Ca+2
2 Exposed binding sites on actin molecules
allow the muscle contraction cycle to occur
ADP + P
ADP + P
Contraction cycle
6 ATP splits, which
provides power to
“cock” the myosin
heads
ADP + P
ADP + P
3 Myosin heads bind
to actin, forming
cross-bridges
ADP
ADP
ATP
ATP
P
ATP
ATP
5 New ATP binds to myosin, releasing linkages
P
ADP + P
4
Cross-bridges pull thin filament (power stroke),
ADP and P released from myosin
16
The Sliding Filament Model
of Muscle Contraction
• When sarcromeres
shorten, thick and thin
filaments slide past one
another
• H zones and I bands
narrow
• Z lines move closer
together
•Page 195
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Sarcomere
Sarcomere
A band
Z line
Z line
A band
Z line
Thin
filaments
1 Relaxed
Z line
Thick
filaments
2 Contracting
(b)
3 Fully contracted
(a)
b: © H.E. Huxley
17
Cross Bridge Cycling
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• Myosin head attaches to actin
binding site, forming cross-bridge
• Myosin cross-bridge pulls
thin filament
Tropomyosin
Troponin
Thin filament
Actin monomers
ADP + P
ADP + P
Thick filament
1 Relaxed muscle
Ca+2
Muscle contraction
Release of Ca+2 from sarcoplasmic
reticulum exposes binding sites on
actin:
• ADP and phosphate
released from myosin
Ca+2
Muscle relaxation
Active transport of Ca+2 into sarcoplasmic
reticulum, which requires ATP, makes
myosin binding sites unavailable.
Ca+2 binds to troponin
ATP
Tropomyosin pulled aside
Binding sites on
actin exposed
Ca+2
• New ATP binds to myosin
ADP + P
Ca+2
ADP + P
Ca+2
2 Exposed binding sites on actin molecules
allow the muscle contraction cycle to occur
• Linkage between actin and
myosin cross-bridge break
• ATP splits
• Myosin cross-bridge goes back
to original position
ADP + P
ADP + P
Contraction cycle
6 ATP splits, which
provides power to
“cock” the myosin
heads
ADP + P
ADP+ P
3 Myosin heads bind
to actin, forming
cross-bridges
ADP
ADP
ATP
ATP
P
ATP
ATP
5 New ATP binds to myosin, releasing linkages
P
ADP + P
4
Cross-bridges pull thin filament (power stroke),
ADP and P released from myosin
18
Relaxation
• __________________ – rapidly decomposes ACh remaining in
the synapse
• Muscle impulse stops
• Stimulus to sarcolemma and muscle fiber membrane ceases
• Calcium moves back into sarcoplasmic reticulum (SR)
• Myosin and actin binding prevented
• Muscle fiber relaxes
19
Energy Sources for Contraction
1) Creatine phosphate and 2) Cellular respiration
• Creatine phosphate – stores energy that quickly converts
ADP to ATP ****
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When cellular ATP is high
Creatine
Creatine
P
When cellular ATP is low
ADP
Creatine
ATP
Creatine
P
ADP
ATP
20
Oxygen Supply and
Cellular Respiration
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• Aerobic Phase
2 In the absence of
sufficient oxygen,
glycolysis leads to
lactic acid
accumulation.
1 Oxygen carried from
the lungs by
hemoglobin in red
blood cells is stored
in muscle cells by
myoglobin and is
available to support
aerobic respiration.
• Citric acid cycle
• Electron transport system
• Occurs in the mitochondria
• Produces most ATP
• __________ stores extra oxygen
• RBC’s carry O2 bound to
hemoglobin
2 ATP
Energy
Pyruvic acid
Lactic acid
Cytosol
• Glycolysis
• Occurs in cytoplasm
• Produces little ATP
Glucose
Mitochondria
• Cellular respiration:
• Anaerobic Phase
Citric acid
cycle
Electron
transport
chain
Synthesis of 34 ATP
CO2 + H2O + Energy
Heat
21
Oxygen Debt
• Oxygen debt – amount of O2
needed by liver cells to use the
accumulated lactic acid to
produce glucose and to restore
muscle ATP and creatine
phosphate concentrations.
• Oxygen not available
• Glycolysis continues
• Pyruvic acid converted to
lactic acid
• _______ converts lactic acid to
glucose
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Glycogen
Energy to
synthesize
Glucose
Energy
from
ATP
ATP
Pyruvic acid
Lactic acid
Glycolysis and
lactic acid formation
(in muscle)
Synthesis of glucose
from lactic acid
(in liver)
22
Muscle Fatigue
• Inability to contract muscle that has been exercised for a prolonged
period of time
• Commonly caused from:
• _________________
• _________________
• _________________
• _________________
• Cramp – sustained, involuntary muscle contraction; occurs when
changes in ECF and the associated motor neurons trigger
uncontrolled stimulation of muscle
23
Heat Production
• By-product of cellular respiration
• Muscle cells are major source of body heat
• Blood transports heat throughout body core
24
8.4: Muscular Responses
• Muscle contraction can be observed by removing a
single skeletal muscle fiber and connecting it to a device
that senses and records changes in the overall length of
the muscle fiber.
25
Threshold Stimulus
• Threshold Stimulus
• Minimal strength required to cause contraction
• Once reached, action potential is generated, resulting in
an impulse that spreads throughout the muscle fiber,
releasing enough Ca2+ ions to activate the cross-bridge
formation; which contracts the muscle
• A single action potential releases enough ACh to bring
the muscle fibers to threshold
26
Recording of a Muscle Contraction
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• Twitch
• Latent period
• Period of contraction
• Period of relaxation
• Refractory period
• All-or-none response
• Page 199
Force of contraction
• Recording a Muscle Contraction
Latent
period
Period of
contraction
Time of
stimulation
Period of
relaxation
Time
27
Summation
• Process by which individual twitches combine
• Produces sustained contractions
• Can lead to tetanic contractions - ___________________
Force of
contraction
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Force of
contraction
(a)
Force of
contraction
(b)
(c)
Time
28
Recruitment of Motor Units
• Single motor neuron
• All muscle fibers controlled
by motor neuron
Motor neuron
• As few as four fibers
of motor unit 1
• As many as 1000’s of
muscle fibers
• ___________________
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Motor neuron
of motor unit 2
Branches of
motor neuron
axon
Skeletal muscle
fibers
29
Recruitment of Motor Units
• Recruitment - increase in the number of motor units
activated
• Whole muscle composed of many motor units
• More precise movements are produced with fewer muscle
fibers within a motor unit
• As intensity of stimulation increases, recruitment of motor
units continues until all motor units are activated
30
Recruitment of motor units
Sustained Contractions
• Smaller motor units (smaller diameter axons) - _____________
• Larger motor units (larger diameter axons) - ____________
• Produce smooth movements
• Muscle tone – ____________________
32
8.5: Smooth Muscles
• Compared to skeletal muscle fibers, smooth muscle fibers
are:
• Shorter – walls of hollow organs
• Single, centrally located nucleus
• Elongated with tapering ends
• Myofilaments randomly organized
• Lack striations
• Lack transverse tubules
• Sarcoplasmic reticula (SR) not well developed
• Involuntary
• Two major types
• Multi-unit
• Visceral
33
Smooth Muscle Fibers
• Multi-unit Smooth Muscle
• Less organized
• Function as separate units
• Fibers function separately
• Iris of eye
• Walls of blood vessels
• Visceral Smooth Muscle
• Single-unit smooth muscle
• Sheets of muscle fibers
• Fibers held together by gap
junctions
• Exhibit rhythmicity
• Exhibit peristalsis
• Walls of most hollow organs
34
Smooth Muscle Contraction
• Resembles
skeletal muscle contraction in that:
• Interaction between actin and myosin
• Both use calcium and ATP
• Both are triggered by membrane impulses
• Different
from skeletal muscle contraction in that:
• Smooth muscle lacks troponin
• Smooth muscle uses calmodulin
• Two neurotransmitters affect smooth muscle
• _________________________________
• Hormones affect smooth muscle
• Stretching can trigger smooth muscle contraction
• Smooth muscle slower to contract and relax
• Smooth muscle more resistant to fatigue
• Smooth muscle can change length without changing
tautness
35
8.6: Cardiac Muscle
• Located only in the heart
• Striated
• Muscle fibers joined together by intercalated discs
• Fibers branch
• Network of fibers contracts as a unit (syncytium)
• Self-exciting and rhythmic
• Longer refractory period than skeletal muscle
• contracts at a fairly steady rate set by the pacemaker
•Single nucleus
•Involuntary
36
Characteristics of Muscle Tissue
38
8.7: Skeletal Muscle Actions
• Skeletal muscles generate a great variety of body
movements.
• The action of each muscle mostly depends upon the kind
of joint it is associated with and the way the muscle is
attached on either side of that joint.
39
Origin and Insertion
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Coracoid process
• Origin – immovable end
• Insertion – movable end
Origins of
biceps brachii
Tendon of
long head
Tendon of
short head
Biceps
brachii
Radius
Insertion of
biceps brachii
40
Interaction of Skeletal Muscles
• Prime mover (agonist) – ____________
• Synergists – ______________
• Antagonist – ____________
42
Know Origin/Insertion of the
following muscles









Epicranius
Masseter
Sternocleidomastoid
Trapezius
Deltoid
Biceps brachii
Palmaris longus
Rectus abdominis
Levator ani









Iliacus
Gracilis
Sartorius
Gastrocnemius
Zygomaticus
Coracobrachialis
Temporalis
Semispinalis capitis
External oblique
8.8: Major Skeletal Muscles
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Frontalis
Orbicularis oculi
Zygomaticus
Masseter
Orbicularis oris
Trapezius
Sternocleidomastoid
Deltoid
Pectoralis
major
Serratus
anterior
Biceps brachii
Brachialis
External oblique
Brachioradialis
Rectus
abdominis
Tensor
fasciae
latae
Sartorius
Rectus femoris
Gracilis
Adductor longus
Vastus medialis
Vastus lateralis
Fibularis longus
Gastrocnemius
Tibialis anterior
Soleus
Extensor
digitorum longus
44
Major Skeletal Muscles
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Temporalis
Occipitalis
Sternocleidomastoid
Trapezius
Deltoid
Teres minor
Teres major
Triceps
brachii
Infraspinatus
Brachialis
Rhomboid
Latissimus
dorsi
External
oblique
Gluteus medius
Gluteus
maximus
Adductor
magnus
Biceps femoris
Gracilis
Semitendinosus
Semimembranosus
Gastrocnemius
Calcaneal tendon
Vastus lateralis
Fibularis longus
Soleus
45
Muscles of Facial Expression
Page 206
46
Muscles of Mastication
Page 206
47
Muscles of Facial Expression
and Mastication
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Epicranial aponeurosis
Frontalis
Epicranius
Occipitalis
Temporalis
Orbicularis oculi
Zygomaticus major
Zygomaticus minor
Masseter
Buccinator
Sternocleidomastoid
Orbicularis oris
Platysma
(a)
Temporalis
Lateral pterygoid
Medial pterygoid
Buccinator
(b)
(c)
48
Muscles That Move the Head
and Vertebral Column
49
Muscles That Move the Head
and Vertebral Column
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Splenius capitis (cut)
Longissimus capitis
Semispinalis capitis
Spinalis capitis
Splenius capitis
Spinalis cervicis
Semispinalis capitis (cut)
Longissimus cervicis
Iliocostalis cervicis
Iliocostalis thoracis
Longissimus thoracis
Spinalis thoracis
Iliocostalis lumborum
Quadratus lumborum
50
Muscles That Move the
Pectoral Girdle
51
Muscles That Move the
Pectoral Girdle
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Levator scapulae
Supraspinatus
Infraspinatus
Teres minor
Teres major
Rhomboid minor
Rhomboid major
Trapezius
Deltoid
Latissimus dorsi
(a)
Trapezius
Rhomboid
minor
Rhomboid
major
Deltoid
Latissimus
dorsi
(b)
(c)
(d)
52
Muscles That Move the Arm
53
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Sternocleidomastoid
Pectoralis minor
Trapezius
Deltoid
Internal intercostal
External intercostal
Pectoralis major
Serratus anterior
Rectus abdominis
Linea alba
(band of connective tissue)
Internal oblique
External oblique
Transversus abdominis
Aponeurosis of external oblique
54
Muscles That Move the Arm
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Levator scapulae
Supraspinatus
Spine of scapula
Deltoid
Infraspinatus
Teres minor
Teres major
Long head of
triceps brachii
Lateral head of
triceps brachii
(a)
Levator scapulae
Supraspinatus
Infraspinatus
Teres minor
Teres major
Triceps
brachii
(b)
(c)
(d)
55
Muscles That Move the Forearm
56
Muscles That Move the Hand
• Flexors (anterior) and extensors (posterior)
57
Muscles That Move the Forearm
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Trapezius
Clavicle
Subscapularis
Deltoid
Coracobrachialis
Medial border
of scapula
Short head of
biceps brachii
Long head of
biceps brachii
Brachialis
(a)
Subscapularis
Coracobrachialis
Biceps brachii
(short and long
heads)
(b)
(c)
Brachialis
(d)
58
Muscles That Move the
Forearm and Hand
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Biceps brachii
Brachialis
Supinator
Pronator teres
Brachioradialis
Brachioradialis
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Extensor carpi
radialis longus
Flexor carpi ulnaris
Flexor digitorum
superficialis
Pronator quadratus
Flexor retinaculum
(a)
(b)
Pronator teres
Flexor digitorum
superficialis
Flexor carpi radialis
Pronator quadratus
(c)
(d)
(e)
59
Cross Section of the Forearm
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Abductor pollicis longus m.
Extensor digitorum m.
Flexor pollicis longus m.
Extensor carpi
ulnaris m.
Radius
Extensor pollicis
longus m.
Extensor carpi
radialis brevis m.
Ulna
Extensor carpi
radialis longus m.
Plane of
section
Flexor digitorum
profundus m.
Pronator teres m.
Ulnar n.
Brachioradialis m.
Ulnar a.
Radial n.
Flexor carpi ulnaris m.
Radial a.
Median n.
Flexor carpi radialis m.
Anterior
Flexor digitorum
superficialis m.
Palmaris longus m.
60
Muscles That Move the Hand
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Triceps brachii
Brachioradialis
Extensor carpi
radialis longus
Flexor carpi ulnaris
Extensor carpi
radialis brevis
Extensor carpi ulnaris
Extensor digitorum
Extensor carpi
radialis longusand
brevis
Extensor retinaculum
Extensor
carpi ulnaris
Extensor
digitorum
(a)
(b)
(c)
61
Muscles of the Abdominal Wall
62
Muscles of the Abdominal Wall
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Rectus abdominis
External oblique
Internal oblique
Transversus abdominis
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Peritoneum
Linea alba
Internal oblique
External oblique
(a)
Skin
(e)
Transversus
abdominis
Rectus abdominis
External oblique
Internal oblique
(b)
(c)
Transversus
abdominis
(d)
63
Muscles of the Pelvic Outlet
64
Muscles of Pelvic Outlet
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Scrotum
Penis
Clitoris
Anus
Ischiocavernosus
Urethral orifice
Bulbospongiosus
Vaginal orifice
Superficial
transversus
perinei
Anus
Levator ani
Gluteus maximus
External anal
sphincter
(a)
(b)
Coccyx
Coccygeus
Levator ani
Rectum
Vagina
Urethra
Urogenital diaphragm
Pubic symphysis
(c)
65
Muscles That Move the Thigh
66
Muscles That Move the Thigh
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Psoas major
Psoas minor
Iliacus
Tensor fasciae
latae
Pectineus
Sartorius
Adductor longus
Sartorius
Rectus femoris
Adductor magnus
Vastus lateralis
Gracilis
Quadriceps femoris
tendon (patellar tendon)
Vastus medialis
Vastus intermedius
Patella
Patellar
ligament
(a)
(b)
Adductor brevis
Adductor longus
Adductor magnus
Gracilis
(c)
(d)
(e)
Psoas major
Psoas minor
Iliacus
(f)
(g)
67
Muscles That Move the Thigh
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Gluteus medius
Tensor fasciae latae
Gluteus maximus
Sartorius
Rectus femoris
Vastus lateralis
Biceps femoris
Iliotibial tract (band)
(a)
Gluteus medius
Gluteus maximus
(b)
(c)
Gluteus minimus
Piriformis
(d)
68
Muscles That Move the Leg
69
Muscles That Move the Leg
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Gluteus medius
Gluteus maximus
Adductor magnus
Vastus lateralis
covered by fascia
Gracilis
Biceps femoris
Semitendinosus
Semimembranosus
Sartorius
Gastrocnemius
Semitendinosus
(a)
Semimembranosus
Biceps femoris
(short head)
(b)
Biceps femoris
(long head)
(c)
70
Muscles That Move the Leg
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Lateral
Medial
Semitendinosus m.
Semimembranosus m.
Long head of
biceps femoris m.
Gracilis m.
Adductor magnus m.
Short head of
biceps femoris m.
Plane
of
section
Sciatic n.
Adductor longus m.
Great saphenousv.
Femoralv . and a.
Sartorius m.
Vastus medialis m.
Shaft of femur
Vastus lateralis m.
Vastus intermedius m.
Adipose tissue
Rectus femoris m.
Skin
Anterior
71
Muscles That Move the Leg
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Plantaris
Iliotibial tract
(band)
Semitendinosus
Soleus
Biceps femoris
Semimembranosus
Gracilis
Sartorius
Gastrocnemius
Gastrocnemius:
Medial head
Lateral head
Fibularis
longus
(b)
(c)
Soleus
Calcaneal tendon
Fibularis
brevis
Flexor digitorum
longus
Tibialis posterior
Flexor retinaculum
Calcaneus
(a)
Flexor digitorum
longus
Fibular
retinacula
(d)
(e)
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Muscles That Move the Foot
73
Muscles That Move the Foot
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Patella
Patellar ligament
Tibialis anterior
Gastrocnemius
Fibularis longus
Extensor digitorum
longus
Soleus
Fibularis brevis
Tibia
Extensor retinacula
(a)
Tibialis anterior
Fibularis tertius
(b)
(c)
Extensor digitorum
longus
Extensor
hallucis
longus
(d)
74
Muscles That Move the Foot
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Biceps femoris
Gastrocnemius
Fibularis longus
Soleus
Vastus
lateralis
Head of fibula
Tibialis
anterior
Extensor digitorum
longus
Calcaneal tendon
Fibularis brevis
Fibularis tertius
Extensor retinacula
Fibular
retinacula
(a)
Fibularis longus
Fibularis brevis
(b)
(c)
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