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Guided Notes for the Muscles
Part 1
5 Golden Rules of Skeletal Muscle
Activity
 All muscles cross at least one joint
 Typically, the bulk of the muscle lies
proximal to the joint crossed
 All muscles have at least two attachments:
the origin and the insertion
 Muscles can only pull; they never push
 During contraction, the muscle insertion
moves toward the origin
2. Each of our over 600 muscles is
attached to bone or other connective
tissue at no less than 2 points. One
of the these points, the origin, is
attached to the immovable or less
movable bone. The insertion is
attached to the movable bone. Body
movement occurs when muscles
contract across joints.
6 Major Body Movements
Name of
Movement
Typical Action
At which joints?
Flexion
Decreases the
angle of the joint
and brings bones
closer together
Hinge joints and
ball-and-socket
joints
Extension
Increases the
angle of joints
Hinge joints and
ball-and-socket
joints
Rotation
Movement of a
bone around its
longitudinal axis
Ball-and-socket
joints and the
atlas/axis
Abduction
Moving a limb
away from the
median plane of
Ball-and-socket
joints
6 Major Body Movements
Name of
Movement
Adduction
Typical Action
Movement of a
limb toward the
body midline
At which joints?
Ball-and-socket
joints
Circumduction The proximal end Ball-and-socket
of a limb remains joints
stationary and
the distal end
moves in a circle
7 Special Muscle Movements
Name of Movement
Description
Where does it
occur?
Dorsiflexion
Lifting the foot so
that its superior
surface approaches
the shin
Plantar flexion
Depressing the foot At the foot (ankle)
so that it is in a
straight plane with
the leg
Inversion
Turning the sole
medially
At the foot (ankle)
Eversion
Turning the sole
laterally
At the foot (ankle)
At the foot (ankle)
7 Special Muscle Movements
Name of Movement
Description
Where does it
occur?
Supination
the forearm rotates The wrist
laterally so that the
palm faces
anteriorally and the
radius and ulna are
parallel
Pronation
the forearm rotates The wrist
medially so that the
radius and ulna
form an X
Opposition
Moving the thumb
to touch the tips of
the other fingers in
the same hand
Saddle joint
between
metacarpal 1 and
the other
5. Origin of the word “muscles”
 The latin word mus means “little
mouse”. This refers to the flexion of
muscles beneath the skin, which
looks like mice scurrying beneath the
skin
6. The essential function of
muscles is contraction, or
shortening.
7. All muscle cells are
elongated, which is why all
muscle cells, regardless of
type, are called muscle
fibers.
8. Skeletal muscle fibers are
cigar-shaped, multinucleate
cells, and the largest of the
muscle-fiber types.
9. Skeletal muscle is also known
as striated muscle because its
fibers appear to be striped, and
it is also known as voluntary
muscle because it is the only
muscle type subject to
conscious control.
10. Tendons and aponeuroses
attach muscles indirectly to
bones, cartilages, or
connective tissue coverings
of each other.
11. Besides acting to anchor
muscles, tendons perform
several functions. The most
important are providing
durability and conserving
space.
12. Smooth muscle has no striations,
and is involuntary, which means that
we cannot consciously control it.
Smooth muscle is generally found in
the walls of hollow visceral organs
such as the stomach, bladder, and
respiratory passages. The function of
smooth muscle is to propel
substances along a definite tract
within the body.
13. Where is cardiac muscle found?
The heart
14. How is cardiac muscle like
skeletal muscle?
It is striated
15. How is cardiac muscle like
smooth muscle?
It is involuntary
16. Cardiac muscle tissue
contraction is regulated by the
heart’s “in-house” pacemaker,
but it can also be stimulated by
the nervous system to “shift into
high gear” for short periods.
Functions of Muscle Tissue
 Producing Movement: a result of
contraction
 Maintaining Posture: counteract the force of
gravity to keep our bodies upright
 Stabilizing Joints: tendons reinforce joints
that have poorly articulating surfaces
 Generating Heat: as ATP is used to power
muscle activity, ¾ of its energy escapes as
heat, which helps maintain body temp.
18. A muscle is fatigued when
it is unable to contract even
though it is still being
stimulated.
19. Muscle fatigue is believed
to be a result of the oxygen
debt that occurs during
prolonged muscle activity.
20. During the recovery period that
occurs after activity, an individual
breathes rapidly and deeply. This
continues until the muscles have
received the amount of oxygen
needed to get rid of the accumulated
lactic acid and make ATP and creatine
phosphate reserves.
21. In isotonic contractions,
the muscle shortens and
movement occurs. Examples
include bending the knee,
rotating the arms, and
smiling.
22. Contractions in which the
muscles do not shorten are called
isometric contractions. These
contractions occur when the
muscle is pitted against some
more or less immovable object.
23. Muscle tone is a state of
continuous partial
contractions. It is the result
of different motor units
throughout the muscle being
stimulated by the nervous
system in a systematic way.
24. Aerobic exercises result in stronger,
more flexible muscles with greater
resistance to fatigue. These changes
come about because the blood supply
to the muscles increases, and the
individual muscle cells form more
mitochondria and store more oxygen.
25. The bulging muscles of a
weightlifter result from resistance, or
isometric exercises.