1. Muscular System – Ch 6 Dancing frog legs:
http://www.youtube.com/watch?v=dmQSP8uUwL8
© 2012 Pearson Education, Inc.

2. The Muscular System Ch 6 Goals
Overview of Muscle Tissues
1. Describe similarities and differences in the structure and function of the three types of muscle tissue
and indicate where they are found in the body.
2. State the 4 main functions of the muscular system and list the main parts of the muscular system.
3. Define and explain the role of the following: endomysium, perimysium, epimysium, tendon, and
aponeurosis. and label them on a diagram.
Microscopic Anatomy of Skeletal Muscle
4. Describe the microscopic structure of skeletal muscle and explain the role of actin- and myosin-
containing myofilaments and label a sarcomere diagram.
Skeletal Muscle Activity
5. Describe how an action potential is initiated in a muscle cell. (neuromuscular junction, acetylcholine,
Ca++…)
6. Describe the events of muscle cell contraction (myosin heads binding to actin fibers & sliding them
past…).
8. Describe three ways in which ATP is regenerated during muscle activity.
9. Define oxygen debt and muscle fatigue and list possible causes of muscle fatigue.
10. Describe the effects of aerobic and resistance exercise on skeletal muscles and other body organs.
Muscle Movements, Types, and Names
11. Define origin, insertion, prime mover, antagonist, synergist, and fixator as they relate to muscles.
12. Demonstrate or identify the different types of body movements. (flexion, extension, hyperextension,
rotation, abduction, adduction, supination, pronation, opposition)
Gross Anatomy of Skeletal Muscles
14. Name and locate the major muscles of the human body (on a torso model, muscle chart, or diagram) and
state the action of each.
© 2012 Pearson Education, Inc.

3. The Muscular System
Muscles are responsible for
all types of body movement
• Movement of
• Skeleton
• Facial expressions
• Eyeball
• Goosebumps
• Iris to control amt of
light into eye
• Heart beating
• Substances through
body
© 2012 Pearson Education, Inc.

4. Characteristics of Muscles
•Skeletal and smooth muscle cells are
elongated (muscle cell = muscle fiber)
•Contraction and shortening of muscles is due
to the movement of microfilaments
•All muscles share some terminology
•Prefixes myo and mys refer to ―muscle‖
•Prefix sarco refers to ―flesh‖
• Composes almost 50% of body mass
© 2012 Pearson Education, Inc.

5. 3 Basic Muscle Types
© 2012 Pearson Education, Inc.

6. Skeletal Muscle Characteristics
• Most are attached by tendons to bones
• Cells are multinucleate
• Striated—have visible banding
• Voluntary—subject to conscious control
• Responds fastest to stimuli
© 2012 Pearson Education, Inc.

7. Connective Tissue Wrappings of Skeletal Muscle
• Cells are surrounded and bundled by connective tissue
• Endomysium—encloses a single muscle fiber (cell)
• Perimysium—wraps around a fascicle (bundle) of muscle fibers
• Epimysium—covers the entire skeletal muscle
• Fascia—on the outside of the epimysium;
covers & separates muscles
Short video showing
live human fascicles
being stimulated
http://www.youtube.co
m/watch?v=1-
dpnqNupns
© 2012 Pearson Education, Inc.

8. Muscle
fiber
Blood vessel (cell)
Perimysium
Epimysium
(wraps entire
muscle)
Fascicle
(wrapped by
perimysium)
Endomysium
(between
fibers)
Tendon
Bone
© 2012 Pearson Education, Inc. Figure 6.1

9. Skeletal Muscle Attachments
• Epimysium blends into a connective tissue attachment
• Tendons—cord-like structures
• Mostly collagen fibers
• Often cross a joint due to toughness and small size
• Aponeuroses—sheet-like structures
• Attach muscles indirectly to bones, cartilages, or
connective tissue coverings
© 2012 Pearson Education, Inc.

10. Skeletal Muscle
Attachments
• Sites of muscle
attachment
• Bones
• Cartilages
• Connective tissue
coverings
• Some facial muscles
attached from skull
to skin – allow for
facial expressions
© 2012 Pearson Education, Inc.

11. Skeletal Muscle Functions
Yea, I’m hot
•Produce movement stuff.
•Maintain posture
•Stabilize joints
•Generate heat
© 2012 Pearson Education, Inc.

12. Microscopic Anatomy of Skeletal Muscle
•Sarcolemma—specialized plasma membrane
•Myofibrils—long organelles inside muscle cell
•Sarcoplasmic reticulum—specialized smooth
endoplasmic reticulum
© 2012 Pearson Education, Inc.

13. Sarcolemma
Myofibril
Dark Light Nucleus
(A) band (I) band
(a) Segment of a muscle fiber (cell)
© 2012 Pearson Education, Inc. Figure 6.3a

14. Microscopic Anatomy of Skeletal Muscle
• Myofibrils are aligned to give distinct bands
• I band = light band
• Contains only thin filaments
• A band = dark band
• Contains the entire length of the thick filaments
© 2012 Pearson Education, Inc.

15. Microscopic Anatomy of Skeletal Muscle
• Sarcomere—contractile unit of a muscle fiber (area b/t two Z
discs)
• Organization of the sarcomere
• Myofilaments
• Thick filaments = myosin filaments
• Thin filaments = actin filaments
© 2012 Pearson Education, Inc.

16. Microscopic Anatomy of Skeletal Muscle
• Thick filaments = myosin filaments
• Composed of the protein myosin
• Has ATPase enzymes
• Myosin filaments have heads (extensions, or cross bridges)
• Myosin and actin overlap somewhat
• Thin filaments = actin filaments
• Composed of the protein actin
• Anchored to the Z disc
© 2012 Pearson Education, Inc.

17. Sarcomere
M line
Z disc Z disc
Thin (actin) filament
Thick (myosin) filament
(c) Sarcomere (segment of a myofibril)
© 2012 Pearson Education, Inc. Figure 6.3c

18. Microscopic Anatomy of Skeletal Muscle
• At rest, within the A band there is a zone that lacks actin
filaments
• Called either the H zone or bare zone
• Sarcoplasmic reticulum (SR)
• Stores and releases calcium
• Surrounds the myofibril
© 2012 Pearson Education, Inc.

19. Thick filament Bare zone Thin filament
(d) Myofilament structure (within one sarcomere)
© 2012 Pearson Education, Inc. Figure 6.3d

20. The Nerve Stimulus and Action Potential
• Skeletal muscles must be stimulated by a motor neuron (nerve
cell) to contract
• Motor unit—one motor neuron and all the skeletal muscle cells
stimulated by that neuron
© 2012 Pearson Education, Inc.

21. Axon terminals at neuromuscular junctions
Spinal cord
Motor Motor
unit 1 unit 2
Nerve
Axon of
Motor neuron motor
cell bodies neuron
Muscle Muscle fibers
(a)
© 2012 Pearson Education, Inc. Figure 6.4a

22. The Nerve Stimulus and Action Potential
Axon terminals at neuromuscular junctions Muscle fibers
•Neuromuscular junction
•Association site of axon
terminal of the motor
neuron and muscle
Branching axon
to motor unit
(b)
© 2012 Pearson Education, Inc. Figure 6.4b

23. © 2012 Pearson Education, Inc. Figure 6.5

24. The Nerve Stimulus and Action Potential
•Synaptic cleft
•Gap between nerve and muscle
•Nerve and muscle do not make contact
•Area between nerve and muscle is filled with
interstitial fluid
© 2012 Pearson Education, Inc.

25. Transmission of Nerve Impulse to Muscle
Synaptic vesicle containing ACh
1 Action potential reaches axon
terminal of motor neuron. Axon terminal of motor neuron
Mitochondrion
2 Calcium (Ca2+) channels Ca2+ Ca2+
open and Ca2+ enters the axon Synaptic
terminal. Sarcolemma
cleft
Fusing synaptic
vesicle
Sarcoplasm
3 Ca2+ entry causes some ACh of muscle fiber
synaptic vesicles to release their Folds of
contents (acetylcholine, a ACh
receptor sarcolemma
neurotransmitter) by exocytosis.
4 Acetylcholine diffuses across
the synaptic cleft and binds to
receptors in the sarcolemma.
© 2012 Pearson Education, Inc. Figure 6.5, step 4

26. Transmission of Nerve Impulse to Muscle
Ion channel in
5 ACh binds and channels open Na+ K+
sarcolemma opens;
that allow simultaneous passage ions pass.
of Na+ into the muscle fiber and
K+ out of the muscle fiber. More
Na+ ions enter than K+ ions leave
and this produces a local change
in the electrical conditions of the
membrane (depolarization), which
eventually leads to an action
potential.
© 2012 Pearson Education, Inc. Figure 6.5, step 5

27. Transmission of Nerve Impulse to Muscle
ACh Degraded ACh
Ion channel closed;
Na+ ions cannot pass.
6 ACh effects are ended by its
breakdown in the synaptic cleft by
the enzyme acetylcholinesterase.
Acetylcholinesterase
K+
© 2012 Pearson Education, Inc. Figure 6.5, step 6

28. The Sliding Filament Theory of Muscle Contraction
• Activation by nerve causes myosin heads (cross bridges) to
attach to binding sites on the thin filament
• Myosin heads then bind to the next site of the thin filament and
pull them toward the center of the sarcomere
• This continued action causes a sliding of the myosin along the
actin
• The result is that the muscle is shortened (contracted)
© 2012 Pearson Education, Inc.

29. Myosin Actin
Z H Z
I A I
(a)
Z Z
I A I
(b) Figure 6.7a–b
© 2012 Pearson Education, Inc.

30. © 2012 Pearson Education, Inc.

31. Muscle Response to Strong Stimuli
•Muscle force depends upon the number of
fibers stimulated
•More fibers contracting results in greater
muscle tension
•Muscles can continue to contract unless they
run out of energy
© 2012 Pearson Education, Inc.

32. Energy for Muscle Contraction
•Initially, muscles use stored ATP for energy
•ATP bonds are broken to release energy
•Only 4–6 seconds worth of ATP is stored by
muscles
•After this initial time, other pathways must be
utilized to produce ATP – there are 3
pathways to produce ATP
© 2012 Pearson Education, Inc.

33. Energy for Muscle Contraction
•Direct phosphorylation of
ADP by creatine phosphate
(CP)
•CP supplies are exhausted
in less than 15 seconds
•About 1 ATP is created
per CP molecule
© 2012 Pearson Education, Inc.

34. Energy for Muscle Contraction
• Anaerobic glycolysis and lactic acid formation
• Reaction that breaks down glucose without oxygen
• Glucose is partially broken down to produce about 2
ATP
• This reaction is not as efficient, but is fast
• Huge amounts of glucose are needed
• Lactic acid produces muscle fatigue
© 2012 Pearson Education, Inc.

35. Energy for Muscle
Contraction
•Aerobic respiration (with
Oxygen)
•Glucose is broken down to
CO2 & H2O, releasing
energy (about 32 ATP)
•In mitochondria
•Slower reaction that
requires continuous O2
© 2012 Pearson Education, Inc.

36. Muscle Fatigue and Oxygen Deficit
•When a muscle is fatigued, it is unable to
contract even with a stimulus
•Common cause for muscle fatigue is oxygen
debt
•Oxygen must be ―repaid‖ to tissue to remove
oxygen deficit
•Oxygen is required to get rid of accumulated
lactic acid
•Increasing acidity (from lactic acid) and lack of
ATP causes the muscle to contract less
© 2012 Pearson Education, Inc.

37. Effect of Exercise on Muscles
•Exercise increases muscle size, strength, and
endurance
•Aerobic (endurance) exercise (biking,
jogging) results in stronger, more flexible
muscles with greater resistance to fatigue
•Makes body metabolism more efficient
•Improves digestion, coordination
•Resistance (isometric) exercise (weight
lifting) increases muscle size and strength
© 2012 Pearson Education, Inc.

38. Five Golden Rules of Skeletal Muscle
Activity
1. With a few exceptions, all skeletal muscles
cross at least one joint.
2. Typically, the bulk of a skeletal muscle lies
proximal to the joint crossed.
3. All skeletal muscles have at least two
attachments: the origin and the insertion.
4. Skeletal muscles can only pull; they never
push.
5. During contraction, a skeletal muscle
insertion moves toward the origin.
© 2012 Pearson Education, Inc.

39. Muscles and Body Movements
•Movement is attained due to a muscle moving
an attached bone
•Muscles are attached to at least two points
•Origin
•Attachment to a moveable bone
•Insertion
•Attachment to an immovable bone
© 2012 Pearson Education, Inc.

40. Muscle
contracting
Origin
Brachialis
Tendon
Insertion
© 2012 Pearson Education, Inc. Figure 6.12

41. Types of Body Movements
• Flexion
• Decreases the angle of the joint
• Brings two bones closer together
• Typical of bending hinge joints like knee and elbow or ball-
and-socket joints like the hip
• Extension
• Opposite of flexion
• Increases angle between two bones
• Typical of straightening the elbow or knee
• Extension beyond 180° is hypertension
• Great video showing these:
http://www.youtube.com/watch?v=-GCgaoRdeaU
© 2012 Pearson Education, Inc.

42. © 2012 Pearson Education, Inc. Figure 6.13a

43. © 2012 Pearson Education, Inc. Figure 6.13b

44. Types of Body Movements
•Rotation
•Movement of a bone around its longitudinal
axis
•Common in ball-and-socket joints
•Example is when you move atlas around
the dens of axis (shake your head ―no‖)
© 2012 Pearson Education, Inc.

45. © 2012 Pearson Education, Inc. Figure 6.13c

46. Types of Body Movements
•Abduction
•Movement of a limb away from the midline
•Adduction
•Opposite of abduction
•Movement of a limb toward the midline
© 2012 Pearson Education, Inc.

47. Special Movements
•Supination
•Forearm rotates laterally so palm faces
anteriorly
•Radius and ulna are parallel
•Pronation
•Forearm rotates medially so palm faces
posteriorly
•Radius and ulna cross each other like an X
© 2012 Pearson Education, Inc.

48. © 2012 Pearson Education, Inc. Figure 6.13g

49. Special Movements
•Opposition
•Move thumb to touch the tips of other
fingers on the same hand
© 2012 Pearson Education, Inc.

50. © 2012 Pearson Education, Inc. Figure 6.13h

51. Types of Muscles
•Prime mover—muscle with the major
responsibility for a certain movement
•Antagonist—muscle that opposes or reverses
a prime mover
•Synergist—muscle that aids a prime mover in
a movement and helps prevent rotation
•Fixator—stabilizes the origin of a prime mover
© 2012 Pearson Education, Inc.

52. Naming Skeletal Muscles
•By direction of muscle fibers
•Example: Rectus (straight)
•By relative size of the muscle
•Example: Maximus (largest)
© 2012 Pearson Education, Inc.

53. Naming Skeletal Muscles
•By location of the muscle
•Example: Temporalis (temporal bone)
•By number of origins
•Example: Triceps (three heads)
© 2012 Pearson Education, Inc.

54. Naming Skeletal Muscles
•By location of the muscle’s origin and insertion
•Example: Sterno (on the sternum)
•By shape of the muscle
•Example: Deltoid (triangular)
•By action of the muscle
•Example: Flexor and extensor (flexes or
extends a bone)
© 2012 Pearson Education, Inc.

55. Head and Neck Muscles
•Facial muscles
•Frontalis—raises eyebrows
•Orbicularis oculi—closes eyes, squints,
blinks, winks
•Orbicularis oris—closes mouth and
protrudes the lips
•Buccinator—flattens the cheek, chews
•Zygomaticus—raises corners of the mouth
•Chewing muscles
•Masseter—closes the jaw and elevates
mandible
•Temporalis—synergist of the masseter,
closes jaw
© 2012 Pearson Education, Inc.

56. Head and Neck Muscles
•Neck muscles
•Platysma—pulls the corners of the mouth
inferiorly
•Sternocleidomastoid—flexes the neck,
rotates the head
© 2012 Pearson Education, Inc.

57. Cranial
Frontalis aponeurosis
Temporalis
Orbicularis
oculi Occipitalis
Zygomaticus
Buccinator
Masseter
Orbicularis
Sternocleidomastoid
oris
Trapezius
Platysma
© 2012 Pearson Education, Inc. Figure 6.16

58. Muscles of Trunk, Shoulder, Arm
•Anterior muscles
•Pectoralis major—adducts and flexes the
humerus
•Intercostal muscles
•External intercostals—raise rib cage
during inhalation
•Internal intercostals—depress the rib cage
to move air out of the lungs when you
exhale forcibly
© 2012 Pearson Education, Inc.

59. Muscles of Trunk, Shoulder, Arm
•Muscles of the abdominal girdle
•Rectus abdominis—flexes vertebral column
and compresses abdominal contents
(defecation, childbirth, forced breathing)
•External oblique—flex vertebral column;
rotate trunk and bend it laterally
•Internal oblique—flex vertebral column;
rotate trunk and bend it laterally
•Transversus abdominis—compresses
abdominal contents
© 2012 Pearson Education, Inc.

60. Muscles of Trunk, Shoulder, Arm
•Posterior muscles
•Trapezius—elevates, depresses, adducts,
and stabilizes the scapula
•Latissimus dorsi—extends and adducts the
humerus
•Erector spinae—back extension
•Quadratus lumborum—flexes the spine
laterally
•Deltoid—arm abduction
© 2012 Pearson Education, Inc.

61. Muscles of Trunk, Shoulder, Arm
•Muscles that arise from the shoulder girdle
and cross the shoulder joint to insert into the
humerus include:
•Pectoralis major
•Latissimus dorsi
•Deltoid
PLAY A&P Flix™: Muscles that act on the shoulder joint and humerus:
An overview.
PLAY A&P Flix™: Muscles of the pectoral girdle.
PLAY A&P Flix™: Muscles that cross the glenohumeral joint.
PLAY A&P Flix™: Movement at the glenohumeral joint: An overview.
© 2012 Pearson Education, Inc.

62. Muscles of the Upper Limb
•Biceps brachii—supinates forearm, flexes
elbow
•Brachialis—elbow flexion
•Brachioradialis—weak muscle; elbow flexion
•Triceps brachii—elbow extension (antagonist
to biceps brachii)
PLAY A&P Flix™: The elbow joint and forearm: An overview.
PLAY A&P Flix™: Muscles of the elbow joint.
PLAY A&P Flix™: Movement at the elbow joint.
© 2012 Pearson Education, Inc.

63. Muscles of the Upper Limb
•Muscles of the forearm, which insert on the
hand bones and cause their movement
include:
•Flexor carpi—wrist flexion
•Flexor digitorum—finger flexion
•Extensor carpi—wrist extension
•Extensor digitorum—finger extension
PLAY A&P Flix™: Muscles that act on the wrist and fingers:
An overview.
PLAY A&P Flix™: Movements of the wrist and fingers (a).
PLAY A&P Flix™: Movements of the wrist and fingers (b).
© 2012 Pearson Education, Inc.

64. Muscles of the Lower Limb
•Muscles causing movement at the hip joint
include:
•Gluteus maximus—hip extension
•Gluteus medius—hip abduction, steadies
pelvis when walking
•Iliopsoas—hip flexion, keeps the upper body
from falling backward when standing erect
•Adductor muscles—adduct the thighs
PLAY A&P Flix™: Muscles that act on the hip joint and femur:
An overview.
PLAY A&P Flix™: Movement at the hip joint: An overview.
© 2012 Pearson Education, Inc.

65. Gluteus medius
Gluteus maximus
Adductor
magnus
Iliotibial tract
Biceps femoris
Semitendinosus Hamstring group
Semimembranosus
Gastrocnemius
(a)
© 2012 Pearson Education, Inc. Figure 6.20a

66. 12th
12th rib thoracic vertebra
Iliac crest
lliopsoas Psoas major
lliacus 5th
lumbar vertebra
Anterior superior
iliac spine
Sartorius
Adductor
group
Rectus femoris
Quadriceps
Vastus lateralis
Vastus medialis
Patella
Patellar
ligament
(c)
© 2012 Pearson Education, Inc. Figure 6.20c

67. Muscles of the Lower Limb
•Muscles causing movement at the knee joint
•Hamstring group—thigh extension and knee
flexion
•Biceps femoris
•Semimembranosus
•Semitendinosus
© 2012 Pearson Education, Inc.

68. Gluteus medius
Gluteus maximus
Adductor
magnus
Iliotibial tract
Biceps femoris
Semitendinosus Hamstring group
Semimembranosus
Gastrocnemius
(a)
© 2012 Pearson Education, Inc. Figure 6.20a

69. Muscles of the Lower Limb
•Muscles causing movement at the knee joint
•Sartorius—flexes the thigh
•Quadriceps group—extends the knee
•Rectus femoris
•Vastus muscles (three)
PLAY A&P Flix™: Muscles that cross the knee joint: An overview.
© 2012 Pearson Education, Inc.

70. Muscles of the Lower Limb
•Muscles causing movement at ankle and foot
•Tibialis anterior—dorsiflexion, foot inversion
•Extensor digitorum longus—toe extension
and dorsiflexion of the foot
•Fibularis muscles—plantar flexion, foot
eversion
•Soleus—plantar flexion
PLAY A&P Flix™: Muscles that act on the ankle and foot:
An overview.
PLAY A&P Flix™: Posterior muscles that act on the ankle and foot.
PLAY A&P Flix™: Movements of the ankle and foot.
© 2012 Pearson Education, Inc.

71. Fibularis longus
Tibia
Fibularis brevis
Soleus
Tibialis anterior
Extensor digitorum
longus
Fibularis tertius
(a)
© 2012 Pearson Education, Inc. Figure 6.21a

72. Gastrocnemius
Soleus
Calcaneal (Achilles)
tendon
Medial malleolus
Lateral
malleolus
(b)
© 2012 Pearson Education, Inc. Figure 6.21b

73. Facial
• Frontalis
Facial
• Orbicularis oculi
• Temporalis
• Zygomaticus
• Masseter • Orbicularis oris
Neck
Shoulder • Platysma
• Trapezius • Sternocleidomastoid
Thorax
• Deltoid • Pectoralis minor
• Pectoralis major
Arm • Serratus anterior
• Triceps brachii
• Biceps brachii • Intercostals
• Brachialis
Abdomen
• Rectus abdominis
Forearm • External oblique
• Brachioradialis • Internal oblique
• Flexor carpi radialis
• Transversus abdominis
Pelvis/thigh
• lliopsoas
Thigh
• Sartorius
• Adductor muscle
Thigh (Quadriceps)
• Rectus femoris • Gracilis
• Vastus lateralis
• Vastus medialis
Leg
• Fibularis longus
Leg
• Extensor digitorum longus
• Gastrocnemius
• Tibialis anterior
• Soleus
© 2012 Pearson Education, Inc. Figure 6.22

74. Neck
• Occipitalis
• Sternocleidomastoid
• Trapezius
Shoulder/Back
• Deltoid
Arm
• Triceps brachii
• Brachialis
• Latissimus dorsi
Forearm
• Brachioradialis
• Extensor carpi radialis
longus
• Flexor carpi ulnaris
• Extensor carpi ulnaris Hip
• Extensor digitorum • Gluteus medius
• Gluteus maximus
Thigh
lliotibial tract
• Adductor muscle
• Hamstrings:
Biceps femoris
Semitendinosus
Semimembranosus
Leg
• Gastrocnemius
• Soleus
• Fibularis longus
Calcaneal
(Achilles)
tendon
© 2012 Pearson Education, Inc. Figure 6.23