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The Bones of the Foot and the Lower Leg
| Bones of the lower leg and foot |
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The bones of the horse's foot can be referred to with many different names.
I've labeled some photos and drawings to help sort out the confusion.
The Coffin Bone is also referred to as the
Pedal Bone or PIII or Third Phalanx.
The Navicular Bone is also referred to as
distal sesamoid.
The Short Pastern Bone can be called P2
or Second Phalanx.
The Long Pastern Bone can be called P1 or
First Phalanx.
Properties of Bone
Bone is dynamic, living tissue! The main structure of bone is calcium and phosphorus, but
bone also contains blood vessels and specialized cells called osteocytes. Calcium and Phosphorus is required
for many other bodily functions, including muscle and nerve activities. One important function of bone is the storage
and release of these minerals, depending on what the body requires. Another important activity of bone is growth (in
young horses) as well as adapting to the stresses and strains of everyday life ... and increased exercise in the form of riding
or driving, etc.
Like any other tissue in the body, bone is constantly active. It is always busy replacing cells,
laying down or absorbing mineral deposits. The bones are also constantly responding to the forces they
receive.
Continuous free exercise ... like living a Natural Lifestyle ... increases bone density. In other words, being stalled or inactive decreases
bone density. This process is the bones normal response to the forces it experiences and is called bone remodeling.
It can remodel to be stronger and denser or it will remodel in the opposite direction.
Being born and then living with unrestricted movement increases the loading capacity of the bones of the
legs and foot. A certain amount of concussion is needed to build strong bones. Much more than we are led to believe.
Being stalled on soft bedding or living and working on soft footing and wearing steel shoes are all counterproductive to the
bones.
Did you know that several weeks of 'stall rest' commonly prescribed by
veterinarians results in bone demineralization and reduction of bone density ... also know as osteoporosis!
Corium
The corium is considered the 'sensitive' structure of the foot as it contains the nerves of the foot. The
corium is modified skin tissue that is highly vascular. The corium nourishes growth. It also dissipates heat and
concussion.
The corium can be divided into the following various sections:
The coronary corium is responsible for growth of the hoof wall and is located inside
the hoof capsule all around the upper perimeter of the hoof (coronary band) to the bulb/heel area where it turns sharply
inward and produces the bar.
The Perioplic corium is a narrow ring of skin located around the top edge of the
hoof. It produces the periople, that skin like appearance covering the top of the hoof wall. It has a high
water content and can dry out quickly ... but also absorb water quickly. It's interesting that the periople was 'discovered'
and named by Bracy Clark almost 200 years ago ... but the history of horses and people/shoeing goes back
thousands of years. It makes me realize and wonder how many other things have been overlooked or misunderstood on the
intricate biological makeup of the horse.
The Laminar corium covers the frontal surface of the coffin bone and lower edges
of the lateral cartilages. It provides nourishment to the laminae which in turn connects or suspends the coffin bone
inside the hoof capsule. When the laminae do not or cannot produce good quality horn (because of restrictions placed
on the movement of the hoof/horse and/or diet issues), the tight connection is compromised and can be lost when the force
of the descending coffin bone causes the layers to shear.
The solar corium covers the solar part of the coffin bone and of course is responsible
for producing the sole. The solar corium is less dense than the coronary corium, therefore the sole is not as hard as
the wall. It is still susceptible to drying out, though not as much as the white line.
The frog and bulb corium produce softer elastic horn having a high moisture content.
Joints, Tendons, Ligaments and Cartilages of the
Foot
The bones of the foot are held together by ligaments that are especially reinforced at the sides.
The lateral cartilages are found on either side of the coffin bone. They are attached through ligaments
to the coffin bone, short and long pastern bones and act like an extension of the 'wings' of the coffin bone (palmar processes).
So it would stand to reason that what happens to them also affects the bones and ligaments nearby.
The extensor tendon runs along the front of the foot and the flexor tendons along the back. The flexor
is attached to the solar part of the coffin bone, the short and long pastern bones as well as the navicular bone.
The Lateral Cartilage is palpable (meaning
that you can feel it) as well as pliable (meaning that it is easily influenced or altered). It is adaptable (to
a point) and flexible. The lateral cartilage is 'soft' compared to bone. It responds to the shape of the harder
hoof wall, as well as any internal forces. Cartilage function becomes impaired by nailing on a shoe, or improper
hoof form caused by 'conventional' trimming.
You can train your eye to 'see' the lateral cartilage. It
is a BIG indicator of what is happening on the inside of the foot. It sometimes reflects itself in the shape and
angle of the hairline at the coronet band.
In the picture on the right, one foot is trimmed 'naturally' (performance
trim) and one foot is trimmed 'conventionally' (pasture trim). For more information on the differences between pasture
trim and performance trim check out the Trimming Differences page. (coming soon)
The picture below is an extreme case of high heels. This horse was
also chronically foundered (wonder why?). He was also on medication for heaves and had MUCH difficulty breathing.
One foot is trimmed and one is yet to be trimmed. This was the initial
trim of this horse and I took the picture lying down on the floor behind and between the hind legs...phew! You can
see the relief and relaxation of the trimmed foot and how easily influenced the lateral cartilage is. Imagine the
long term chronic pain this horse was dealing with.
In addition to medication for 'heaves' and 'founder' he was confined
to the stall because of his 'illnessness'.
Today, at 18 years old he is full of life and vigor. He was taken off all
medication once he was started on the 'program'. He got a new lease on life ... and a new body and feet rebuilt. He did
this in less than one years time ... and he's not alone. It is amazing each time for me to see these 'hopeless' cases
come full circle. The power of Nature is awe inspiring!
| EXTREME VIEW OF THE AFFECTS OF HIGH HEELS |
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| WHICH FOOT LOOKS MORE COMFORTABLE TO YOU?? |
FOOT SHAPE
SO many of today's horses are given a high heel foot shape ... or they are
trying to "stand them up" or "get more heel". If that's the case, the heels are generally underrun or crushed.
The concept or idea of a horse with a 'good' heel is very
misunderstood and thought to only mean the length of the heel wall. In actuality the
heel is an area of the foot which includes the external structures of
the hoof wall, the heel/bar triangle, the back of the frog and the heel bulbs ... but also includes the internal
structure of digital cushion. The digital cushion is often crushed and atrophied when not put into proper use from too
'high' a heel or when bounded with an iron ring.
People are led to believe that a desirable hoof has lots of heel (heel wall) ...
the truth is, this kind of shape is the cause of many a lameness issue. The results of the trimming styles
that accompany shoeing or conventional 'pasture trims' are contraction, decreased blood flow, decreased nerve function,
bar impaction, heel pain, mystery lameness, founder, etc. The resulting chronic low grade pain can be related to behavioral
and training 'problems' as well.
The digital cushion is often misunderstood or completely ignored. It requires the natural expansion
and contraction (restricted, altered or eliminated by shoeing or improper hoof shape/trimming) that the horses foot has
upon impact through movement. The digital cushion plays an important role in pumping the blood through the foot. Movement
is important and standing still for 1/2 days or more does nothing to develop this built in 'Air Nike'.
The bars of the foot are made of very hard horn material and if not trimmed correctly or receive little
wear will grow and jam up inside the hoof capsule. In essence 'squish' and pinch the digital cushion and
lateral cartilages ... among other things. The picture shows this happening to this horse's foot. He was diagnosed
with a neurological 'disease' when the real reason was right there in his hoof form. NO vet or farrier commented on the
feet ... they were 'normal' for him. Once his trim style was corrected, he no longer showed the symptoms of
this neurological problem that the conventional professionals believed he had. He had NO symptoms less than one week later.
The Front feet shape vs. the Hind feet shape
There are differences in the normal shape of the front feet compared to the normal
shape of the hind feet. Even the coffin bone reflects these differences.
Much too often we see the front and the hinds trimmed like each other - all 4 feet looking alike
- somewhat oval ... a cross between the normal front shape and the normal hind shape.
The normal front foot is virtually round and is symmetrical
in shape with shallower concavity than the hinds. This shape is designed to support over 60% of the horses overall weight. The
two front feet should mirror each other.
The front feet slightly 'toe in'.
The normal hind foot is asymmetrical in shape
with a slightly 'pointy' toe, and has a 'deeper' concavity. The inside of the hind foot is narrower when viewed
from the bottom. Looking from the front (or back) the inside wall is slightly steeper than the outside wall. And finally
the angle of the hind foot toe wall is always steeper than the fronts on the same horse. This makes the hind feet reliable for
surefooted locomotion (fast getaways).
The two hind feet should also mirror each other.
The hind feet slightly 'toe out'.
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Pictures will enlarge and open in a new window if you click on them.
Really LOOK at the picture above.
Look at the coffin bone and see how it is shaped. You can see where the frog apex would join. You can imagine why a cross
section view of this bone gives the appearance of being a small triangle pointy bone when in fact it is a large 'hoof' shaped
specialized bone.
The coffin bone is very perforated, resembling a (hard) sponge.
These porous 'holes' allow tiny branches of arteries, veins and nerves to pass through the bone.
Attached to the ends of the coffin bone are the lateral cartilages.
They are affected by shoeing and conventional trimming.
It has been proven that shoeing or improper trimming restricts and alters the
normal intended movement of the foot, restricting the blood supply to the foot. Overall circulation is compromised. Nerves
are pinched and function is reduced as well. This may be one reason why shod horses 'appear'
sound when in shoes but 'dead lame' when out of them.
Some people still think that 'some' horses can't go barefoot. I beg
to differ. ALL horses will benefit from assigning the foot it's intended form and function. The body systems will
respond - the immune system is raised - health is elevated.
| COFFIN BONE SHOWING NATURAL CONCAVITY |
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| COFFIN BONE OR PEDAL BONE OR PIII |
| Coffin and Navicular bone in hand |
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| Showing size comparison |
| LAMINAE INSIDE THE HOOF WALL |
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| CAN YOU SEE THE DIFFERENCE |
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| WHICH FOOT LOOKS MORE RELAXED AND 'NORMAL'? |
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| WIDE LOW NATURAL PERFORMANCE FOOT |
| REPUTABLE FARRIER WORK |
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| THE PROPERTIES OF STEEL DON'T CONFORM TO THE FOOT PROPERTIES |
This page is NOT yet finished....so keep tuning in for additions....
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