Muscles and bones are interesting organs.
Sure, you could look at the obvious
and say they provide structure,
they provide movement,
and that’s what’s right there in front of you.
But they’re also organs that make blood,
make energy, and do a lot more for our body.
So the idea that I want to change here
is not just looking at the structure
of the musculoskeletal system,
but look at the interaction of
the musculoskeletal system
with the whole body because
the bone is an organ.
It’s made up of living tissue
and it makes blood in the tip of the bone.
It stores calcium and phosphate
which goes back and forth within the blood.
It helps regulate potassium.
It’s highly vascular and highly innervated
so that we have a sense of what’s going on.
But when most people look
at the bone, they say,
“Yeah, it defines the structure of the body,
the size of the body.”
And we want to get past that
and move forward.
When we talked about the ribs, we talked
about it being a protective case.
The skull is also a protective case.
A lot of our bones protect
the vasculature and the
nerves underneath it
and it does provide leverage for movement,
activity, and other things.
The bone system—the skeletal system—
develops neural crest cells
early on in development—early
on in embryology.
The 4th week is when it starts
and by the 9th week it’s pretty
and the bony skeleton has been set
and it just needs to grow in size.
And when we look at where growth
is occurring in bones,
when we’re adults,
it’s usually the metaphyseal plate.
So we’re going to look at epiphysis, the end
which stores a lot of the blood
and produces blood,
the metaphysis which is
right below it which
holds the growth plate,
and the diaphysis or the shaft,
and each part of the bone has a
different function in metabolism.
If there’s damage or disruption
to the metaphyseal plate,
then growth is going to be impaired.
And that’s why when you’re looking at x-rays,
you want to make sure, particularly
particularly in young patients, that
it’s intact and not separated
and that there’s no lines through it
or impairment of the metaphyseal plate.
Abnormal development can be
from birth, from heredity.
It can be from differences in use,
it can be from trauma,
and some kind of deformities
occur in each level.
Torsional deformities are when
people walk wrong,
use their limbs wrong, or have breaks.
Tibial torsion will cause toeing in
and other changes in the foot.
So that’s something to be aware of.
Congenital deformities include limb
length, limb size, limb symmetry,
and also you can have differences in
the number of fingers and toes,
and the numbers of bones in the body.
So those are all things to keep in mind
when we look at the body structure system
and the skeletal system.
Some deformities are apparent
and look different because they are
different and they stand out.
Others may be unapparent, like
the number of wrist bones
or the number of bones in the hand or foot,
may or may not be noted.
But those differences can
dislocations, and distortions of bone
that are going to effect functioning.
Hereditary deformities like
may lead to increased breaks
and difficulty in bones’ functioning
as efficiently as we would like.
You can also see a development of
developmental dysplasia of the hip
as a common bone deformity
as well as club foot,
or talipes is another term used
to describe club foot.
One of the most common deformities
we see is scoliosis
and scoliosis could be a
with abnormal twisting
or it could be a rotational deformity,
and a lot of that is determined by heredity.
So always assess whether or not a scoliosis
is something that is lateral or rotational
and you also want to note if it
goes away with motion.
A lot of early scoliosis is postural
and that changes as someone gets
older and as the bones solidify.
Some of it is structural and
will not change
with sidebending or motion.
We do classify scoliosis as
neuromuscular, or idiopathic.
Paget’s disease is a skeletal disorder
that has excessive bone
destruction and repair.
The bones are going to look
different on x-ray
and the bones will function differently,
and may not be able to provide
the same support to the body
in terms of blood formation
or mineral regulation
without growing out of proportion
to what we’d expect.
So you may have increased bony deposition
and you may have increase in the
size and shape of the bone
in certain areas of the body.
So you’re going to have the increased
that may be a tower skull, it
may be long arms,
but they’re going to look different.
Bones tend to grow and get
reformed by themselves.
They have different mechanisms
that tell many to be reformed.
So when somebody is active,
their muscle use, their pressure
they put on the bones,
will say that the bone needs to be reformed.
Wolff’s law talks about the area
of greatest bone growth
is the area of greatest pressure.
So if you lift weights, you’re going
to help grow bones.
The other force that’s involved is
called piezoelectric forces,
and those are the electric forces
that come from the muscle
that stimulate bone growth
where the muscles are using
the bones for leverage.
So it’s a nice feedback mechanism
that determines how big,
how long, and what size and shape
the bone is going to be.
We also have some feedback from
the vascular system in cytokines
that will help reform the bone.
We do know that there are 4 types
of cells involved in bony regrowth.
Most of the time we talk about
osteoblasts and osteoclasts
but there are also osteoprogenitor cells
which are stem cells that
can become either.
There are also osteocytes
which is after laying down bone,
the osteoblast gets caught in that area,
and becomes more mature
and helps maintain that area of bone.
And osteoclasts are the ones that
remove the bone matrix
and help stimulate reformation
of bony tissue.
So every canaliculus, every blood
supplied area of bone,
can reform every 3 months.
Not everyone is doing it at the same
time, so every 2 to 3 years,
a bone is completely reformed
and that maintains the structural integrity
and maintains the strength of the bone.
When we talk about the bone,
bones are an encased organ,
and they’re encased by periosteum.
The periosteum has an outer fibrous layer
where the muscles attach
and an inner osteogenic layer
which helps maintain the integrity,
and the osteogenic layer also has
osteoclasts and osteoblasts
that are not caught like the osteocytes.
The vascular supply is critical for
maintaining nutrition to the bone,
making sure bones have what it needs,
and giving feedback to the periosteal
and the bone system.
When we talk about bone growth
and bone structure,
it’s important to know what the
bones should look like,
which ones are predetermined by
which ones are going to be determined
by your ethnic group, your sex,
and basically your history of what size
you are meant to be.
We also know that at different
ages it changes
even though the bone shape and
structure is determined
at about 9 weeks of gestation.
Bone growth in the first 4
years of life is critical.
That’s when arm length, leg length,
and the length of the trunk
versus the length of the extremities
pretty much gets set.
We normally say that the
ASIS to the shoulder
should be equal to the distance of
the ASIS to the medial malleolus
as long as nutrition is good,
proper sun exposure is obtained,
and you get the minerals and
nutrients you need to grow.
In areas where you do not
have good nutrition,
where people are sun sensitive—they stay
inside—and don’t get proper activity,
they’re going to have smaller leg
length to trunk length.
The trunk will be longer than the legs.
You bring them from that environment
to a healthy environment with a good
diet and good nutrition, their legs—
if it’s under 4 years of age—will grow longer.
And again, the nutrition is important
whether or not they get calcium,
and the other nutrients necessary
Other issues that matter
in terms of bone growth is
People who are more sedentary are going
to have smaller, weaker bones.
Weight, up until a certain level, matters.
If you’re underweight, you’re not going
to have strong bones,
and this is usually set by 25 years of age.
So people who are chronically thin,
will not reach their predetermined bone
mass activity that’s possible.
Other things we’re seeing in today’s
modern society, is lifestyle choices
are effecting bone growth.
People who try and maintain a low body mass,
a low body weight tend not to reach it.
People who drink a lot of
alcohol and caffeine,
people who smoke tend not to
reach peak muscle mass.
And we’re seeing supplements blanching bone
and we’re seeing drugs like steroids
and antiseizure medicines,
also can effect the ability of the body
to get to a particular body structure
that is most efficient, most
effective and strongest.
So those are all things we
have to be aware of.