According to Merriam Webster, anatomy is a branch of morphology that deals with the structure of organisms. Sound confusing? It is. To make it more simple, the definition of Structure according to Merriam Webster is the manner of construction. Basically how a horse is put together. To fully understand a horse's anatomy, you have to look under the skin.
Next is the muscular system, which is also is vital for customizers. The muscling dictates how the skeleton will move.
Next is the deltoids, which determines the slope of the shoulder, and makes up a majority of the of the front of the shoulder. One of the deltoids is mostly covered by other muscles, but is very prominent
With the skin and fat added, the shoulder looks like this:
The shoulder is hinged from the wither, therefore acting as a fulcrum. Here is a horse in a trot, notice how the whole shoulder has come forward? The same thing happens when the leg comes back, the shoulder goes with it.
The other muscle is the omotransversarius, which runs up to the ears. This is one of the most noticeable muscles in the neck.
Next is the deeper part of the neck, I confess I don't know much about the under layers, but here's a picture of what it looks like.
First is the biceps, which are these muscles here:
The next muscle is the semitendinosus, which runs right behind the biceps.
Here's a horse doing the exact opposite, instead of pulling his leg forward for the next stride, he is pushing off.
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