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The Stiffening Rods Of The Body-machine
Category: OUR TELEPHONE EXCHANGE AND ITS CABLES
Source: A Handbook Of Health
What Bones Are. The bones are not the solid foundation and framework
upon which the body is built, as they are usually described. They are
simply a framework of rods and plates which petrified, or turned into
spongy limestone after the body was built, to make it firmer and stiffen
it for movement. All the animals below the fishes, such as worms,
sea-anemones, oysters, clams, and insects, get along very well without
any bones at all; and when we are born, our bones, which haven't fully
set yet, are still gristly and soft. The cores of the limbs, as they
begin to stiffen, first turn into gristle, or cartilage, and later into
bone; indeed, many of our bones remain gristle in parts until we are
fifteen or sixteen years of age. This is why children's bones, being
softer and more flexible than those of grown-up people, are not so
liable to break or snap across when they fall or tumble about; and why,
too, they are more easily warped or bent out of shape through lack of
proper muscular exercise and proper food.
Bones are strips of soft body-stuff soaked with lime and hardened, like
bricklayer's mortar, or concrete. When you know the shape of the
body, you know the bones; for they simply form a shell over the head and
run like cores, or piths, down the centre of the back, and down each
joint of the limbs.
In turning into spongy limestone, or animal concrete, they have become
one of the deadest tissues in the body. They are tools of the muscles,
the levers by which the muscles move the limbs and body about; they
never do anything of their own accord. On account of their lifelessness
and lack of vitality, they are rather easily attacked by disease, or
broken by a blow or fall. There are such a large number of bones (two
hundred and six, all told), and they resist decay and last so much
longer after death than any other parts of the body, that they fill our
museums and text-books of anatomy, form most of our fossils, and have
thus given us rather an exaggerated idea of their importance during
The Frame-Work of the Body. Just look at any part of the body and
imagine that it has a bony core of about the same general shape as
itself, and you can reason out all the bones of the skeleton. To begin
at the top, the skull is a box of strong, plate-like bones, which have
hardened to protect the brain as it grew; and the shape of its upper, or
brain, part is exactly that of the head, as you can easily feel by
laying your hands upon it. Then come bony shells, or sockets, for the
eyes and nose; and, below these, two heavy half-circles of bone, like
the jaws of a steel trap, to carry the teeth.
The thickness of the lower jaw and the size and squareness of the angle
where it bends upward to be hinged to the skull, below the ear, are what
give the appearance of squareness and determination to the faces of
strong, vigorous men or women. If we want to imply that a person has a
feeble will, or weak character, we say he has a weak jaw.
The skull rests upon the top of the backbone, or spinal column, which,
instead of being one long solid bone, is made up of a number of pieces,
or sections, known as vertebrae. Each one of these vertebrae has a ring,
or arch, upon its back. These, running one after the other, form a
jointed, bony tube to protect the spinal cord, or main nerve-cable of
the body, which runs through it.
Although the backbone can bend forward or backward, or twist from side
to side a little, by the little pieces of bone of which it is built up
gliding and turning upon one another, it is really very stiff and rigid,
so as to protect the spinal cord and prevent its being stretched or
pinched. Most of the movements which we call bending the spine are
really movements of other joints which connect the body or head with
it. When we bend our necks, for instance, we hardly bend the backbone at
all, as most of the movement is made in the joint at the top of it,
between it and the skull. Similarly, when we bend our backs, we really
bend our backbones very little; for most of the movement comes at the
hip joints, between the thighs and the hip bones.
Each of the limbs has a single, long, rounded bone in the upper part,
known in the arm as the humerus, and two bones in the lower part.
These last are known as the radius and ulna (the funny bone) in
the forearm, and the tibia and fibula in the leg. The shoulder-joint
is made by the rounded head of the humerus fitting into the shallow cup
of the scapula, or shoulder-blade. It is shallower than the hip joint
to allow it freer movement; but this makes it weaker and much more
easily dislocated, or put out of joint,--the most so, in fact, of any
joint in the body.
The hip joints are deep, strong, cup-shaped sockets upon each side of
the hip bones, or pelvis, into which fit the heads of the femurs or
thigh bones. When the hip joint does become dislocated, it is very hard
to put back again, on account of its depth and the heavy muscles
surrounding it. It is quite subject to the attack of tuberculosis, or
The joints, or points at which the bones join one another, look rather
complicated, but they are really as simple as the bones themselves. Each
joint has practically made itself by the two bones' rubbing against each
other, until finally their ends became moulded to each other, and formed
the ball-and-socket, or the hinge, according to whichever the movements
of the bend required. The ends, or heads, of the bones which form a
joint are covered with a smooth, shining coating of cartilage, or
gristle, so that they glide easily over each other.
Around each joint has grown up a strong sheath of tough, fibrous tissue
to hold the bones together; and, inside this, between the heads of the
bones, is a very delicate little bag, or pouch, containing a few drops
of smooth, slippery fluid (synovial fluid) to lubricate the movements
of the joint. This is sometimes called the joint oil, though it is not
Bones are covered with a tough skin, or membrane (periosteum). They
are hardest and most solid on their surfaces, and hollow, or spongy,
inside. The long bones of the limbs are hollow, and the cavity is filled
with a delicate fat called marrow--just as an elderberry stem or
willow-twig is filled with pith. This tubular shape makes them as strong
as if they were solid, and much lighter.
The short, square, and flattened bones of the body, such as those of the
wrist, the skull, and the hips, instead of being hollow inside are
spongy; and the spaces in the bone-sponge are filled with a soft tissue
called the red marrow in which new red and white corpuscles for the
blood are born, to take the place of those which die and go to pieces.
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