SLIGHTLY MOVABLE. In these joints
the bones are held together by broad flat-
tened disks of cartilage and ligaments (e.g.,
vertebrae and symphysis pubis).
FREELY MOVABLE. Such joints include
the knee, hip, and shoulder. These joints
are further subdivided into (figs. 3-23A and
HINGE JOINTS . . . . . . . . . .elbow, finger, and knee
BALL-AND-SOCKET JOINTS . . . . shoulder and hip
Joint movements are generally divided into
GLIDING is the simplest type of motion. It is
one surface moving over another without any
rotary or angular motion. This motion exists be-
tween two contiguous or adjacent surfaces.
Figure 3-23A.Hinge joint.
Figure 3-23B.Ball-and-socket joint.
ANGULAR motion decreases or increases the
angle between two adjoining bones. The more
common types of angular motion are:
Flexionbending the arm or leg.
Extensionstraightening or unbending, as
in straightening the forearm, leg, or
Abductionmoving an extremity away
from the body.
Adductionbringing an extremity toward
ROTATION is a movement in which the bone
moves around a central point without being
displaced, such as turning the head from side to
CIRCUMDUCTION is movement of the hips
Other types of movement generally used to in-
dicate specific anatomical positions include the
SUPINATION is turning upward, as in plac-
ing the palm of the hand up.
PRONATION is turning downward, as in
placing the palm of the hand down.
EVERSION is turning outward, as in turning
the sole of the foot to the outside.
INVERSION is turning inward, as in turning
the sole of the foot inward.
Muscles make up about one-half of the total
body weight. Their main functions are threefold:
Providing movement, including internal
functions such as peristalsis in the
Maintaining body posture through muscle
tone, as in the muscles of the head, neck
and shoulders, which keep the head up.
Providing heat through chemical changes
that take place during muscle activity, such
as mild exercise that warms the body on
addition, muscles are involved in such
essential bodily functions as respiration, blood