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Figure 3-8.—Striated (voluntary) muscle. | Up
Hospital Corpsman 3 & 2 - Intro Navy Nursing manual for hospital training purposes | Next
DIVISIONS OF SKELETON |
nutrients than any other body tissue. The
basic cell of the nervous tissue is the neuron
(fig. 3-11). This highly specialized cell
receives stimuli from, and conducts im-
pulses to, all parts of the body.
ORGANS
As a group of similar cells form tissues, similar
tissues form organs such as the heart, liver, and
kidneys. These organs are grouped together to
form systems, such as the urinary system that is
composed of the kidneys, ureters, bladder, and
urethra.
Figure 3-11.—Neuron.
THE SKELETAL SYSTEM
The skeleton is the bony framework of the
body, composed of 206 bones (fig. 3-12). It sup-
ports and gives shape to the body; protects vital
organs; and provides sites of attachment for ten-
dons, muscles, and ligaments. The skeletal bones
are joined members that make muscle movement
possible.
ANATOMY OF BONES
OSTEOLOGY is the study of the structure of
bone. Bone is made up of inorganic mineral salts,
calcium and phosphorus being the most prevalent,
and an organic substance called ossein. When
human bone is soaked in dilute acid until all in-
organic mineral salts are washed out, all that re-
mains is a flexible piece of tissue that can easily
be bent and twisted. The inorganic mineral salts
give bone its strength and hardness.
Bone consists of a hard outer shell, called com-
pact tissue, and an inner spongy, porous portion,
called cancellous tissue (fig. 3-13). In the center
of the bone is the MEDULLARY CANAL, which
contains marrow. There are two types of marrow,
red and yellow. Yellow marrow is ordinary bone
marrow in which fat cells predominate. It is found
in the medullary canals and cancellous tissue of
long bones. Red marrow is one of the manufac-
turing centers of red blood cells and is found in
the articular ends of long bones and in cancellous
tissue. At the ends of the long bones is a smooth,
glossy tissue that forms the joint surfaces. This
tissue is called articular cartilage because it articu-
lates (joins) with, fits into, or moves in contact
with similar surfaces of other bones. The thin
outer membrane surrounding the bone is called
Figure 3-12.—Human skeleton.
the PERIOSTEUM. An important function of the
periosteum is to supply nourishment to the bone.
Capillaries and blood vessels run through the peri-
osteum and dip into the bone surface, supplying
it with blood and nourishment. The periosteum
3-6
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