March 25, 2009
Parts of the Hoof
It's always good to know a little about your mule's anatomy. This overview of the equine hoof will be very helpful if you need to talk with your vet or farrier about a hoof issue.
The hoof wall is the hard shell encasing the equine foot. It is their equivalent of our fingernails. The hoof wall protects and supports the bone and tissue structures inside. It is very important that the hoof wall be properly trimmed on a regular basis. If the hoof wall is allowed to grow too long or is left at the wrong angle, it can be very damaging to the rest of the foot and cause many foot problems. A healthy hoof wall should be smooth on the outside, with no signs of ridges or rings and should also not be chipping or cracked.
Parts of the hoof wall:
The sole is the softer flat tissue on the bottom of the hoof. It has a concave shape and is lighter in color.
The frog is the triangular more rubbery piece of tissue under the center and back portion of the hoof. A healthy frog should be wide across the back and have a smooth calloused appearance. The frog acts as a cushion below the bone structure inside the hoof as the mule takes each step.
Cleft of the Frog
The cleft of the frog also know as the collateral grooves are the grooves that run along both sides of the frog, where the frog joins with the sole.
Bulbs of the Heel
The bulbs of the heel are the rounded rubbery tissue at the back of the hoof. It extends up from the frog up to the hairline at the back of the hoof.
The coronet band is along the top of the hoof wall just below the hair line. This is softer tissue where the hoof wall is grown. Damage or injury to the coronet band can cause uneven growth of the hoof wall.
The white line is the area on the bottom of the hoof where the hoof wall joins with the sole. This is where the laminae come out at the bottom of the hoof wall. In the first photo above, you can see that that hoof's white line is thicker than some. This is typical of equines who have had laminitis and their laminae have stretched.
The Laminae is the tissue inside the hoof that connects the inside of the hoof wall to the inner hoof capsule and coffin bone. When a horse founders or gets Laminitis, the laminae tissue becomes inflamed, and if the laminitis is severe enough or goes untreated, the laminae will stretch, letting the coffin bone rotate down - thus causing the classic rotated coffin bone seen in many foundered equines.
The term Pastern refers to the section between the top of the hoof and the fetlock joint.
The fetlock is the first noticeable joint above the hoof.
Pedal Bone/Coffin Bone
The Pedal bone is the last bone in the equine leg. It is also known as the Coffin Bone or also sometimes referred to as P1.
The second bone up in the equine leg is the short pastern or Second Phalanx, also known as P2.
The third bone up in this column of foot bones is the long pastern or Third Phalanx or P3.
Just below and behind the joint between the Coffin bone and the Second Phalanx is a smaller bone called the Navicular bone.
Digital Extensor Tendon
This tendon runs down the front of the mule's ankle and foot. It connects to the front of each of the bones in the column. The job of this extensor tendon is to extend the bones, or lift them forward. Thus this tendon is the one that lifts the foot forward and up when the mule takes a step. The term "Digital" says that this tendon is part of the equine foot.
Deep Digital Flexor Tendon
This tendon runs along the back side of the equine foot bone column, opposite the Digital Extensor Tendon. The Deep Digital Flexor Tendon's job is to flex, or pull downward and back, the mule’s foot. Thus this tendon is the one that holds the mule's foot bones up straight upright when the mule is standing on them, instead of letting them just collapse under the mule's weight. It is also used to flex the ankle, or pull it up toward the back when the mule lifts it off the ground. The flexor and extensor tendons work against each other to flex or extend the column of bones as the mule moves.
The Navicular Bursa is a special fluid filled sack that sits right between the Navicular bone and the Deep Digital Flexor Tendon. It protects this tendon and bone from abrasion as the tendon slides over this area.
That's a good overview of the parts of a mule or donkey's hoof. Now you'll know what your farrier and vet are talking about next time you talk with them about your equine's hooves!
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Posted by Kristie Jorgensen at March 25, 2009 08:33 PM