Muscular System Parts and Functions

1. The Muscular System
Specialized tissue that enable the body and its parts to move.

2. Anterior View

3. Posterior View

4. TRIVIA!
• How many muscles are there in the human body?
• Answer: 640 Muscles
• The muscles make up about 40 % of the body mass.
• What is the longest muscle in the body?
• Answer: The Sartorius
• The Sartorius runs from the outside of the hip, down and across to the inside of the knee. It twists and
pulls the thigh outwards.
• What is the smallest muscle in the body?
• Answer: The Stapedius
• The Stapedius is located deep in the ear. It is only 5mm long and thinner than cotton thread. It is involved
in hearing.
• What is the biggest muscle in the body?
• Answer: The Gluteus Maximus
• The Gluteus Maximus is located in the buttock. It pulls the leg backwards powerfully for walking and
running.

5. Introduction
• Bones and joints do not
produce movement
• The human body has more
than 600 individual
muscles
• Muscles cause bones and
supported structures to
move by alternating
between contraction and
relaxation

6. Functions of the Muscles
•Movement
•Maintenance of posture and muscle tone
•Heat production
•Protects the bones and internal organs.

7. Muscle Classification
• Functionally
• Voluntarily – can be moved at will
• Involuntarily – can’t be moved
intentionally
• Structurally
• Striated – have stripes across the fiber
• Smooth – no striations

8. Functions of Muscle
Muscle has the ability to
contract, permitting muscles to
perform various functions
• Functions:
• Movement
• Stability
• Control of body openings and
passages
• Heat production

9. The 3 Types of Muscles
Skeletal Muscle Smooth Muscle Cardiac Muscle
3 Types of Muscles

10. Structure of Skeletal Muscle
• Epimysium:
• Tendon connective tissue extends to form fibrous sheath.
• Fascicles:
• Connective tissue extends into the body of the muscle.
• Composed of columns of muscle fibers.
• Each fascicle surrounded by perimysium.
• Striated in appearance:
• Striations produced by alternating A and I bands.

11. Structure of Skeletal Muscle(continued)

12. Structure of Skeletal Muscle
• Composed of Skeletal Muscle, nervous tissue, blood and connective tissues.
• Separated from adjacent muscles held in position by connective tissue called fascia
• Fascia- Sorrounds each muscle and may project the end of its muscle fibers to form
cordlike tendon.
• Tendon- fibers intervene in the periosteum of a bone attaching the muscle to the
bone.
• Epimysium-connective tissue that closely sorounds a skeletal muscle.

13. • Perimysium- extends inward from the epimysium.
• Separates the muscle tissue into small sections.
• Fascicles- contained in sections of the perimysium
• Small bundles of the skeletal fibers.
• Lies within a layer of connective tissue in the form of a covering called endomysium.
• Sarcolemma- beneath the muscle cell membrane, contains oval
nuclei and mitochondria
• Myofibrils- play fundamental role in muscle contraction
mechanism.
• A.Thick filament-myosin
• B. Thin filament- actin

14. Striation Patterns
a. I bands(dark bands)- composed
of thin actin filaments
b. Z lines- center of the I bands
c. A bands(dark bands)- Thick myosin
filaments
-thick and thin overlap(H-
zone)- only thick filaments
- M line(consist of proteins
that help hold the thick
filaments in place

15. A skeletal muscle is composed of a
variety of tissues, including layers of
connective tissue. Fascia covers the
surface of the muscle, epimysium lies
beneath the fascia, and perimysium
extends into the structure of the muscle
where it separates muscle cells into
fascicles. Endomysium separates
individual muscle fibers.

16. Motor Unit
When somatic neuron is activated, all the muscle fibers it
innervates contract with all or none contractions.
• Innervation ratio:
• Ratio of motor neuron: muscle fibers.
• Fine neural control over the strength occurs when many small motor
units are involved.
• Recruitment:
• Larger and larger motor units are activated to produce
greater strength.

17. Motor Unit (continued)
 Each somatic neuron together
with all the muscle fibers it
innervates.
 Each muscle fiber receives a
single axon terminal from a
somatic neuron.
 Each axon can have collateral
branches to innervate an equal
# of fibers.

18. Movement
• Skeletal muscles
• Attached to bones by tendons
• Cross joints so when they contract, bones they attach to move
• Smooth muscle
• Found on organ walls
• Contractions produce movement of organ contents
• Cardiac muscle
• Produces atrial and ventricular contractions
• This pumps blood from the heart into the blood vessels

19. Smooth Muscle
• Fibers are thin and
spindle shaped.
• No striations
• Single nuclei
• Involuntary
• Contracts slowly

20. Smooth Muscle
• They fatigue… but very slowly
• Found in the circulatory system
• Lining of the blood vessels
• Helps in the circulation of the blood
• Found in the digestive system
• Esophagus, stomach, intestine
• Controls digestion
• Found in the respiratory system
• Controls breathing
• Found in the urinary system
• Urinary bladder
• Controls urination

21. Cardiac Muscle
• Cells are branched and appear
fused with one another
• Has striations
• Each cell has a central nuclei
• Involuntary

22. Cardiac Muscle
• Found ONLY in the heart
• Contractions of the heart muscles pump blood throughout the
body and account for the heartbeat.
• Healthy cardiac muscle NEVER fatigues  or else…

23. Skeletal Muscle
 Fibers are long and
cylindrical
 Has many nuclei
 Has striations
 Have alternating
dark and light bands
 Voluntary

24. Skeletal Muscle
•Attached to skeleton by tendons
•Causes movement of bones at the joints.
•And yes… they do fatigue
•Muscle fatigue activity  what substance
forms causing muscle fatigue???

25. Functions of Skeletal Muscle
• Movement – muscle move bones by pulling not
pushing.
• Synergists – any movement is generally accomplished
by more than one muscle. All of the muscles
responsible for the movement are synergists.
• The one that is most responsible for the movement
is the Prime Mover (agonist).

26. Functions of Skeletal Muscle
• Movement
• Antagonists – muscles and muscle groups usually work in pairs
– example the biceps flex your arm and its partner the triceps
extend your arm. The two muscles are antagonists, i.e. cause
opposite actions.
– when one contracts the other relaxes.
• Levators – muscle that raise a body part.

28. Functions of Skeletal Muscle
• Maintenance of posture or muscle tone
• We are able to maintain our body position because of tonic
contractions in our skeletal muscles. These contractions
don’t produce movement yet hold our muscles in position.
• Heat production – contraction of muscles produces
most of the heat required to maintain body
temperature.

29. Movement of Muscles
• Origin: the attachment of
the muscle to the bone
that remains stationary
• Insertion: the attachment
of the muscle to the bone
that moves
• Belly: the fleshy part of
the muscle between the
tendons of origin and/or
insertion
origin
insertion
belly

30. Movement of skeletal muscle
• These muscles move when the brain sends messages to the
muscle
• Always work in pairs
• 2 movements of skeletal muscle
• Contraction (shorten)
• Extension (lengthen)

31. Categories of skeletal muscle actions
• Categories Actions
• Extensor Increases the angle at a joint
• Flexor Decreases the angle at a joint
• Abductor Moves limb away from midline of body
• Adductor Moves limb toward midline of body
• Levator Moves insertion upward
• Depressor Moves insertion downward
• Rotator Rotates a bone along its axis
• Sphincter Constricts an opening

33. Properties of Skeletal Muscle
Activity (single cells or fibers)
Slide 6.13Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Irritability – ability to receive and
respond to a stimulus
 Contractility – ability to shorten when an
adequate stimulus is received

34. Nerve Stimulus to Muscles
Slide 6.14Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Skeletal
muscles must
be stimulated
by a nerve to
contract (motor
neruron)
 Motor unit
One neuron
Muscle cells
stimulated by
that neuron Figure 6.4a

35. Nerve Stimulus to Muscles
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Neuromuscular
junctions –
association site
of nerve and
muscle
Figure 6.5b

36. Nerve Stimulus to Muscles
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Synaptic cleft –
gap between
nerve and
muscle
Nerve and
muscle do not
make contact
Area between
nerve and muscle
is filled with
interstitial fluid Figure 6.5b

37. Transmission of Nerve Impulse to
Muscle
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Neurotransmitter – chemical released
by nerve upon arrival of nerve impulse
The neurotransmitter for skeletal muscle is
acetylcholine
 Neurotransmitter attaches to receptors
on the sarcolemma
 Sarcolemma becomes permeable to
sodium (Na+)

38. Transmission of Nerve Impulse to
Muscle
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Sodium rushing into the cell generates
an action potential
 Once started, muscle contraction
cannot be stopped

39. Body Movements
Flexion – bending a body part
Extension – straightening a body
part
Hyperextension – extending a body
part past the normal anatomical
position
Dorsiflexion – pointing the toes up
Plantar flexion – pointing
the toes down
Abduction – moving a
body part away from
the anatomical position
Adduction – moving a
body part toward the
anatomical position

40. Body Movements (cont.)

41. Body Movements (cont.)
Circumduction – moving a body
part in a circle
Pronation – turning the palm of
the hand down
Supination – turning
the palm of the
hand up

42. Body Movements (cont.)
Inversion – turning the sole of
the foot medially
Eversion – turning the sole of
the foot laterally
Retraction – moving a body
part posteriorly
Protraction – moving a
body part anteriorly

43. Body Movements (cont.)
Elevation – lifting a body part;
for example, elevating the
shoulders as in a shrugging
expression
Depression – lowering a body
part; for example, lowering
the shoulders

45. Head and Neck Muscles
Figure 6.14

46. 22-46
Muscles of the Head
• Sternocleidomastoid
• Pulls the head to one
side
• Pulls the head to the
chest
• Frontalis
• Raises the eyebrows
• Splenius capitis
• Rotates the head
• Allows it to bend to the side
• Orbicularis oris
• Allows the lips to pucker

47. 22-47
Muscles of the Head (cont.)
• Orbicularis oculi
• Allows the eyes to close
• Zygomaticus
• Pulls the corners of the mouth
up
• Platysma
• Pulls the corners of the mouth
down
• Masseter and temporalis
• Close the jaw

48. Trunk Muscles
Slide 6.39Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.15

49. Deep Trunk and Arm Muscles
Slide 6.40Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.16

50. Muscles of the Pelvis, Hip, and Thigh
Slide 6.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.18c

51. Muscles of the Lower Leg
Slide 6.42Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.19

52. 22-52
Arm Muscles
• Pectoralis major
• Pulls the arm across the
chest
• Rotates and adducts the
arms
• Latissimus dorsi
• Extends and adducts the
arm and rotates the arm
inwardly

53. 22-53
Arm Muscles (cont.)
• Deltoid
• Abducts and extends
the arm at the shoulder
• Subscapularis
• Rotates the arm
medially
• Infraspinatus
• Rotates the arm
laterally

54. 22-54
Arm Muscles (cont.)
• Biceps brachii
• Flexes the arm at the
elbow
• Rotates the hand laterally
• Brachialis
• Flexes the arm at the
elbow
• Brachioradialis
• Flexes the forearm at the
elbow

55. 22-55
Arm Muscles (cont.)
• Triceps brachii
• Extends the arm at
the elbow
• Supinator
• Rotates the forearm
laterally (supination)
• Pronator teres
• Rotates the forearm
medially (pronation)

56. 22-56
Wrist, Hand, and Finger Muscles
• Flexor carpi radialis and
flexor carpi ulnaris
• Flex and abduct the wrist
• Palmaris longus
• Flexes the wrist
• Flexor digitorum profundus
• Flexes the distal joints of the
fingers, but not the thumb

57. Wrist, Hand, and Finger Muscles (cont.)
• Extensor carpi radialis longus and brevis
• Extend the wrist and abduct the hand
• Extensor carpi ulnaris
• Extends the wrist
• Extensor digitorum
• Extends the fingers, but not the thumb

58. 22-58
Respiratory Muscles
• Diaphragm
• Separates the thoracic cavity from
the abdominal cavity
• Its contraction causes inspiration
• External and internal
intercostals
• Expand and lower the ribs during
breathing

59. Abdominal Muscles
• External and internal obliques
• Compress the abdominal wall
• Transverse abdominis
• Also compresses the abdominal wall
• Rectus abdominis
• Flexes the vertebral column
• Compresses the abdominal wall

60. Pectoral Girdle
• Trapezius
• Raises the arms
• Pulls the shoulders downward
• Pectoralis minor
• Pulls the scapula downward
• Raises the ribs

61. 22-62
Leg Muscles
• Iliopsoas major
• Flexes the thigh
• Gluteus maximus
• Extends the thigh
• Gluteus medius and minimus
• Abduct the thighs
• Rotate them medially

62. Leg Muscles (cont.)
• Adductor longus and
magnus
• Adduct the thighs
• Rotate them laterally
• Biceps femoris,
semitendinosus, and
semimembranosus
• Known as the hamstring
group
• Flex the leg at the knee
• Extend the leg at the thigh

63. Leg Muscles (cont.)
• Rectus femoris, vastus
lateralis, vastus medialis,
and vastus intermedius
• Extend the leg at the knee
• Sartorius
• Flexes the leg at the knee
and thigh
• Abducts the thigh, rotating
the thigh laterally but
rotating the lower leg
medially

64. Ankle, Foot, and Toe Muscles
• Tibialis anterior
• Inverts the foot and points the
foot up (dorsiflexion)
• Extensor digitorum longus
• Extends the toes and points the
foot up
• Gastrocnemius
• Flexes the foot and flexes the leg
at the knee

65. Ankle, Foot, and Toe Muscles (cont.)
• Soleus
• Flexes the foot
• Flexor digitorum
longus
• Flexes the foot and
toes

66. Muscle Contraction
• Sequence
• Electrical impulse travels down a motor neuron. When it reaches the end,
acetylcholine (chemical) is released into the synapse.
• Acetylcholine bind to special receptors on the muscle cell and causes an
electrical impulse to spread over the cell.
• The sarcomeres shorten and the muscle cell contracts.

67. MUSCLE
MUSCLE
FIBER
MYOFIBRIL
SARCOMERE

68. Mechanism Of Muscle Contraction
•Step 1. Nerve impulse, travels towards
the synaptic knob.
•Step 2. Ca++ ion from ECF enter into
the synaptic knob through calcium
channels.

69. Mechanism Of Muscle Contraction
•Step 3. As Ca++ enter into synaptic
knob, Ach. Vesicles ruptures and Ach.
release out into synaptic cleft by
exocytosis.

70. Mechanism Of Muscle Contraction
•Step 4. Ach diffuses across the
neuromuscular junction and binds to
the receptor sites on postsynaptic
membrane.

71. Steps 1-4

72. Mechanism Of Muscle Contraction
•Step 5. Stimulating of the receptor causes
conformational change in post synaptic
membrane and generate an action
potential.
Ach. destroyed by an enzyme
(acetylcholinestrase)

73. Mechanism Of Muscle Contraction
•Step 6. This action potential travels
along the length of muscle fiber, and
then penetrates deep into the muscle
through the T-tubular system.

74. Mechanism Of Muscle Contraction
•Step 7. The electrical impulse
stimulates the sarcoplasmic reticulum
to release calcium into the (a
contractile unit of a mofibril) area.

75. Mechanism Of Muscle Contraction
• Step 8. Calcium bind with tropnin-C and activates myosin
ATPase.
As myosin ATPase become active. Tropomyosin slipped off, G-
action exposed.
ATPase react with ATP.
ATP+ATPase ADP+ ~P
Muscle contraction takes place.
Ca++

76. Mechanism Of Muscle Contraction
• Muscle contraction occurs when calcium is
pumped back into the sarcoplasmic
reticulum, away from the actin and myosin.
• When Calcium moves in this way, the actin
and myosin cannot interact, and the muscle
relaxes.

77. SLIDING FILAMENT

79. CONTRACTION
In Contraction
•I- band disappear
•H- band disappear
•M- band disappear
•Length of sarcomere decreases.

80. Sarcomere Relaxed

81. Sarcomere Partially contracted

82. Sarcomere completely contracted

83. Sarcomere relaxed

84. Stages Of Muscle Contraction

85. Isotonic contraction
• Produces movement
• Most of the time movement is of this type
• Used in
• Walking
• Running
• Movement of a part of the body (eg. Hand movement)

86. Isotonic contraction

87. Isometric contraction
• Muscular contraction involves shortening of the contractile
elements, but because muscles have elastic and viscous elements
in series with the contractile mechanism, it is possible for
contraction to occur without an appreciable decrease in the
length of the whole muscle
• Such a contraction is called isometric ("same measure" or length)

88. Isometric contraction

89. Isometric contraction
• Produces no movement
• Used in
• Standing
• Sitting
• Postural control