The
Muscular
System
Objectives
❑ Enumerate the different
muscles in the body.
❑Explain the types,
characteristics and functions of
muscles.
❑Execute the different body
movements.
Muscular System
- Is a set of tissues in the body
with the ability to change
shape.
- Muscles are responsible for
all types of body movement –
they contract or shorten and
are the machine of the body.
Characteristics of Skeletal Muscles
Voluntary – muscles that are under conscious control
and can be controlled at will or we can choose when to use
them.
Non-Voluntary – muscle governing reflex functions
and not under direct voluntary control especially : smooth
muscle.
Three Basic Types
of
Muscle
•Skeletal Muscle
•Cardiac Muscle
•Smooth Muscle
Smooth muscle
lines the inside of
blood vessels and
organs, such as
the stomach, and
is also known as
visceral muscle.
Cardiac muscle
stimulates its own
contractions that
form our heartbeat.
Signals from the
nervous system
control the rate of
contraction.
It contains the
contractile elements
necessary to produce
movement. Skeletal
muscles contribute
about 45% of the
body weight of males
and about 36% for
females.
Did You Know?
❑Muscles make up 40% of your total body
weight. (BMI)
❑The smallest muscles are found in the
middle ear (Stapedius). At just 1 millimeter in
length, its purpose is to stabilize the smallest
bone in the body, the STAPES.
Did You Know?
❑To take one step, you use 200
muscles.
❑Your tongue is the tough working
muscle in your body.
❑It takes 17 muscles to smile and
43 to frown.
Characteristics
of
Muscles
Characteristics
1. Contractability ~ its ability to shorten and thicken (when muscles work they
contract, that is, they get shorter and thicker)
2. Extensibility ~ ability to stretch (when muscle is relaxed it becomes longer
and thinner)
3.Elasticity ~ ability to return to original length.
4. Irritability ~ ability to respond to stimulus.
5. Tone ~ slight tension in the muscles at all times, even at rest.
Functions of Muscles
❑Produce movement
❑Maintain posture
❑Stabilize joints
❑Generate heat
Types of Muscle Contractions
Isotonic Contractions
➢The tension in the muscle
remains constant despite a
change in muscle length
➢The muscle shortens
Types of Muscle Contractions
Isometric Contractions
➢Tension in the muscles
increases
➢The muscle is unable to
shorten
➢A muscle generates tension
without changing length
Muscle and Body Movement
❑ Movement is
attained due to a
muscle moving an
attached bone
Muscle and Body Movement
❑Muscles are attached to at
least two points
➢ Origin – attachment to a
moveable bone
➢ Insertion – attachment to an
immovable bone
Effects of Muscles
❑Results of increased muscle use
✓Increase in muscle size
✓Increase in muscle strength
✓Increase in muscle efficiency
✓Muscle becomes more fatigue resistant
Types of
Body
Movements
Types of Body Movements
1. Adduction ~ moving a body part
toward the midline.
2. Abduction ~ moving a body part
away from the midline.
Types of Body Movements
3.Flexion (Flexor) ~ decreasing the angle
between two bones and body part.
4. Extension ( Extensor) ~ increasing the
angle between two bones and body part.
Types of Body Movements
5. Rotation ~ a circular motion which turns a body part
on its axis.
6. Sphincters ~ ring like muscles that close body
openings.
example: rectum
7. Elevators ~ lift a part of the body
Types of Body Movements
8. Depressors ~ lower a part of the body.
9. Supination ~ the act of rotating the arm so the palm
of the hand is upward.
10. Pronation ~ the act of rotating the arm so the palm of
the hand is turned downward.
Types of
Body
Muscles
Types of Body 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.
Naming of Body Muscles
❑ Direction of Muscle Fibers
➢ Example: RECTUS (straight)
❑ Relative Size of the Muscle
➢ Example: MAXIMUS (largest)
Naming of Body Muscles
❑ Location of the Muscle
➢ Example: many muscles are named
for bones (e.g., temporalis)
❑ Number of Origins
➢ Example: TRICEPS (three heads)
Naming of Body Muscles
❑Location of the Muscles Origin and Insertion
➢ Example: STERNO (on the sternum)
❑Shape of the Muscle
➢ Example: DELTOID (triangular)
❑Action of the Muscle
➢ Example: FLEXOR and EXTENSOR (flexes or extends a bone)
Types of
Joint
Movements
Joint Movement
❑ ELBOW FLEXION – decreasing the angle between the
lower arm and the upper arm.
❑ ELBOW EXTENSION – increasing the angle between the
lower arm and upper arm.
❑ KNEE FLEXION - decreasing the angle between the lower
leg and the upper leg.
❑ KNEE EXTENSION - decreasing the angle between the
lower leg and the upper leg.
Joint Movement
❑ SHOULDER ADDUCTION – decreasing the angle between
upper arm and the side.
❑ SHOULDER ABDUCTION – increasing the angle between
upper arm and the side.
❑ SHOULDER FLEXION – increasing the angle between the
upper arm and the chest.
❑ SHOULDER EXTENSION – decreasing the angle between
the upper arm and the chest.
Joint Movement
❑ SHOULDER HORIZONTAL FLEXION – decreasing the angle
between the upper arm and the chest.
❑ SHOULDER HORIZONTAL EXTENSION – increasing the
angle between the upper arm and the chest.
❑ HIP FLEXION – decreasing the angle between the thighs
and the torso.
❑ HIP EXTENSION – increasing the angle between the
thighs and the torso.
Joint Movement
❑ TRUNK FLEXION – decreasing the angle between the
chest and the stomach.
❑ TRUNK EXTENSION – increasing the angle between the
chest and the stomach.
❑ ANKLE FLEXION – decreasing the angle between the foot
and the shin.
❑ ANKLE EXTENSION – decreasing the angle between the
foot and the shin.
Joint Movement
❑ WRIST FLEXION - decreasing the angle between the palm
and the underside of the forearm.
❑ WRIST EXTENSION - increasing the angle between the
palm and the underside of the forearm.