The muscles that move bones are commonly called the skeletal muscles. They
are also called striated (striped) muscles due to their physical appearance. Since these
muscles are normally controlled by conscious thought (you "command" your arm to rise,
for example), they are also called "voluntary" muscles. Muscles are connected to the
bone by connective tissue called tendons.
Involuntary muscles, such as the muscles found in the blood circulatory
system and digestive system, perform their function with no need of
Section II. FRACTURES
COMPLETE AND INCOMPLETE FRACTURES
A fracture occurs when a bone is broken. The break may only be a crack in the
bone (incomplete fracture) or the bone may be broken into two separate parts (complete
fracture). Any fracture can be serious. A fracture of a large bone like the femur can
result in a significant loss of blood that, in turn, can result in hypovolemic shock.
Complete fractures are also dangerous because the sharp ends of the fractured bone
can injure muscle tissues, nerves, and blood vessels. If a rib is fractured in two places,
the bone segment between the two fractures may "float" and damage an organ (such as
the heart or a lung) or a major blood vessel (such as the aorta).
CLOSED AND OPEN FRACTURES
a. Closed Fracture. A closed fracture (see figure 1-3A) is a fracture in which
the skin is not broken. A closed fracture may result in significant loss of blood due to
internal bleeding (bleeding into surrounding body tissues or into a body cavity). This
blood loss may result in shock.
b. Open Fracture. An open fracture is one in which the skin is broken
(penetrated). The source of the penetration may have been the end of a fractured bone
(see figure 1-3B) or a foreign object, such as a bullet, which penetrated the skin and
fractured the bone (see figure 1-3C). If an open wound is caused by a fractured bone,
the bone may remain visible or it may slip back below the skin and muscle tissues. An
open fracture usually results in more blood loss than does a closed fracture since the
blood can escape through the open wound. There is a risk of shock from blood loss.
Infection is also a major concern since the skin is broken.