[1][2] Anatomically homologous to the two largest bones found in the human finger, the pastern was famously mis-defined by Samuel Johnson in his dictionary as "the knee of a horse".

This joint has limited movement, but does help to disperse the concussive forces of the horse's step and also has some influence on the flexion or extension of the entire leg.

If the angle does not match, it could be an indication of poor farrier work, but some horses may have underlying conformational defects that can not be modified through farriery alone.

Because there is less need for shock absorption in the hindleg, its pasterns are somewhat more upright than those of the front leg, to increase its strength (about 49-59 degrees).

It improves the animal's ability to travel on uneven terrain, helps it withstand the rigors of a competition or race, and makes the gait more comfortable for the rider.

When the horse puts weight on his leg, the fetlock sinks closer to the ground, which is a needed response as it helps to absorb the shock of the footfall.

This not only makes the gaits uncomfortable due to the jarring, but also increases the chance of arthritis and may shorten the animal's career.

Due to the lack of shock absorption, horses that have upright pasterns should be kept off hard surfaces whenever possible.