If The Shoe Fits #8

© Randy Sublett

(Randy, a practicing farrier, writes articles oriented to horse owners.)

I know what you are saying to yourself by now, "This guy is starting to ramble on about horse anatomy when he is supposed to talking horseshoes." Okay. You caught me. But a good farrier had better understand the anatomy of the horse's legs.

We've briefly discussed tendons and ligaments, both of which should be dealt with in more depth, as many of the common injuries to horses involve either of these structures. When a tendon has a tear or rupture in it, it is called a "bowed tendon" and when the strain or rupture is on the severe side, scar tissue that inhibits the proper functioning of the tendon is almost unavoidable. Ligaments can also be sprained or ruptured. A sprain is the condition in which the ligament is torn, but the bones that it connects together are not dislocated. There are more ligaments in the lower leg than there are tendons. It should be noted here that ligaments attach bone to bone.

When tendons have a long distances to travel, they are protected by synovial sheaths, so called because these sheaths contain a lubricant called synovial fluid. Synovial fluid has the consistency of heavy mineral oil and is extremely slippery, thus allowing the tendon to easily glide within the sheath.

There are four tendons in the lower leg that concern us at this point. The lateral extensor tendon and the main extensor tendon are located on the fore part of the leg. Bringing up the rear part of the leg are the superficial flexor tendon and the deep flexor tendon. Simply put, extensor tendons extend the leg and flexor tendons flex the leg. The lateral extensor tendon operates differently in the fore leg than it does in the hind leg. In the fore leg, the lateral extensor tendon runs separately but somewhat parallel to the main extensor tendon and attaches to the upper part of the long pastern bone. In the hind leg, the lateral extensor tendon will usually join up with the main extensor tendon just a bit below the hock.

The main extensor tendon in both the fore leg and hind leg attaches itself to the upper portion of the long pastern bone, the upper part of the short pastern bone, and finally, to the upper part of the coffin bone.

The superficial flexor tendon runs down the back of the leg and divides just below the fetlock. It then attaches to the lower portion of the long pastern bone and the short pastern bone at the pastern joint. In the hind leg, this tendon has little muscular function (remembering that tendons attach muscle to bone, and act more like a ligament of the "stay apparatus"). In short, the stay apparatus is the system of ligaments that allow a horse to sleep standing up.

The deep flexor tendon runs down the rear of the leg and attaches only at the bottom rear of the coffin bone or what is referred to as the "semi lunar crest". This tendon passes over the navicular bone just before it attaches. More on that in the future.

Randy welcomes comments or questions about his articles.

Randy Sublett
P.O. Box 9
Telluride, CO 81435

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