62 Introduction to Medical Terminology
Copyright Goodheart-Willcox Co., Inc.
Suffi x Meaning
-tomy process of cutting; incision
-tonia tone; tension
-trophy condition of growth or
development
Anatomy and Physiology
What is your favorite sport or activity? Do you
enjoy volleyball, football, swimming, cycling, or
dancing? Without muscles, none of these activi-
ties—or other forms of movement—would be
possible.
The muscular system is composed of different
kinds of tissue that work together to perform sev-
eral essential functions. These essential functions
include
• holding body parts in position and making
movement possible;
• providing a protective covering for the internal
organs;
• producing, through movement, nearly 85 per-
cent of the heat that keeps the body warm;
• moving food through the digestive system;
• aiding blood fl ow through the veins as blood
returns to the heart; and
• assisting with the movement of fl uids through
the ducts and vessels of other body systems.
Figure 3.1 illustrates some of the major muscles
in the body. As you view the fi gure, consider what
muscles of the body perform what functions.
Ponder This
Trapezius, deltoid, gluteus maximus, sartorius...
it’s all Greek and Latin. Why do you think so
many structures in the body get their names from
long, sometimes difficult-to-pronounce words that
originated in ancient cultures? Why would modern-
era science and medicine benefit from the continued
use of terms that come from Greek and Latin?
On average, muscles make up 40 to 45 percent
of your body weight. Your body has more than
630 muscles that help you perform different kinds
of movement.
Fascinating Fact
Muscle Tissue Types
Muscle is a type of body tissue made up of
bundles of fi bers (long, slender cells) that are held
together by connective tissue. When nerves stim-
ulate muscle fi bers, the fi bers contract (become
shorter and thicker), causing body movement.
Muscles that are stimulated to move through
conscious control are called voluntary muscles.
The phrase “conscious control” does not mean
that your brain has to think about, or plan, every
muscular action before it is performed. Rather,
voluntary muscular activity is action that you can
control through the force of your will (for example,
swallowing). Much voluntary muscular activity
happens when you are giving little, if any, thought
to the actions that are performed by your body. By
contrast, muscles that are not stimulated to move
through conscious control are called involuntary
muscles. You cannot force yourself to move these
muscles through willpower (for example, the
heart beating).
Voluntary and involuntary muscles in the body
come in three types: skeletal muscle, smooth mus-
cle, and cardiac muscle.
Skeletal muscle, also called striated (strigh-AY-
ted) muscle, is voluntary muscle that is attached to
bone and can be contracted or relaxed through con-
scious control. Striated muscle has a distinctively
striped appearance and is composed of muscle
fi bers. Skeletal muscle fi bers are long, slender cells
grouped and held together with connective tissue
and covered with fascia (FASH-ee-uh), a band or
sheet of fi brous tissue that encloses a muscle or
group of muscles. Skeletal muscle is found in the
scalp, face, mouth, pharynx (throat), larynx (voice
box), neck, chest, vertebral column, arms and
hands, abdomen, back, and legs and feet.
Smooth muscle,alsocalledvisceral(VIS-uh-ruhl)
muscle, is a type of involuntary muscle, meaning it
is not controlled by conscious thought processes.
Smooth muscle surrounds internal organs and is
found throughout your respiratory tract, stomach,
intestines, and urinary tract. Smooth muscle con-
tracts and relaxes to move contents through body
system passageways. This involuntary move-
ment, known as peristalsis (PEER-ih-STAHL-sis),
enables blood to travel through arteries and veins,
food to move through the stomach and intestines,
and a fetus to be expelled through the birth canal.