 Muscular System Student Notes
 What makes up the Muscular System?
o Over 600 muscles make up the system know as the
Muscular system. Muscles are bundles of muscle
fibers held together by connective tissue. All Muscles
have certain properties or characteristics.
 Three Types of Muscles
o Smooth Muscle Fibers
o Skeletal Muscle Fibers
o Cardiac Muscle Fibers
 Smooth Muscle (Visceral)
o Found in the internal organs of the body such as
those of the digestive and respiratory systems, and
the blood vessels and eyes.
 Skeletal Muscle
o It is attached to bones and causes body movement.
 Cardiac Muscle
o Form the walls of the heart and contracts to
circulate blood.
 Related Health Careers
o Athletic Trainer
o Chiropractor
o Doctor of Osteopathic Medicine
o Massage Therapist
o Myologist
o Orthopedist
o Physiatrist
o Physical Therapist
o Podiatrist
o Prosthetist
o Sports Medicine Physician
 Four Important Functions
o Attach to bones to provide voluntary movement.
o Produce heat and energy for the body.
o Help maintain posture.
o Protect internal organs.
 Diseases and Abnormal Conditions
o Fibromyalgia is chronic, widespread pain in specific
muscle sites.
o Muscular dystrophy is actually a group of inherited
diseases that lead to chronic, progressive muscle
atrophy. Most types result in total disability and
early death.
o Myasthenia gravis is a chronic condition where
nerve impulses are not properly transmitted to the
muscles.
o Muscle spasms, or cramps, are sudden, painful,
involuntary muscle contractions.
o A strain is an over stretching of or injury to a muscle
and/or tendon. Prolonged or sudden muscle
exertion is usually the cause.
 Key Terms
o Abduction- moving body part towards the midline.
o Adduction- moving a body part away from the
midline.
o Cardiac muscle- forms the walls of the heart and
contracts to circulate blood.
o Circumduction- moving in a circle at a joint, or
moving one end of a body part in a circle while the
other end remains stationary, such as swinging arm
in a circle.
o Contract- become short and thick.
o Contractibility- muscle fibers that are simulated by
nerves contract with causes movement.
o Contracture- a severe tightening of a flexor muscle
resulting in bending of a joint.
o Elasticity- allows the muscle to return to its original
shape after it has contracted or stretched.
o Excitability- irritability, the ability to respond to a
stimulus such as a nerve impulse.
o Extensibility- the ability to be stretched.
o Extension- increasing the angle between two bones,
or straightening a body part.
o Fascia- a tough, sheet like membrane that covers
and protects the tissue.
o Flexion- decreasing the angle between two bones, or
bending a body part.
o Insertion- the end that moves when the muscle
contracts.
o Involuntary- cardiac muscle and visceral muscle.
They function without conscious thought or control.
o Muscle tone- muscles that are partially contracted at
all times, even when not in use.
o Muscular system- over 600 muscles that make up
the system.
o Origin- the end that does not move when a muscle
attached to the bone.
o Rotation- turning a body part around its own axis;
for example, turning the head from side to side.
o Skeletal muscle- attached to bones and causes body
movement.
o Tendons- strong, tough, connective-tissue cords.
o Visceral (smooth) muscle- found in the internal
organs of the body such as those of the digestive and
respiratory systems, and the vessels and eyes.
o Voluntary- a person has control over its action.
 Random Facts
o The hardest working muscle is in the eye.
o It takes 17 muscles to smile and 48 to frown.
o There are muscles in the root of your hair that give
you goose bumps.
o The largest muscle in your body is the Gluteus
Maximus.