Usual disclaimer: These are my opinions!
There is no real physical centaur to compare against, so the best I can do is make an educated guess. If you prefer a design other than this, that's fine, but this is what I'm going to keep drawing. If you disagree, fine, but do so politely, and above all, please don't ask I draw things your way. I know how I think it'd work, and that ain't gonna change.
So before we can talk about, say, the cardiovascular system, we have to talk about basic terminology for the parts of the body. These are the ones I use, derived from a mixture of human terms and horse terms, and a few new ones:Major regions:
- Head: Everything above the neck.
- Torso: Everything from the top of the neck to the top of the hips.
- Barrel: Everything from the hips to the start of the hindquarters, but excluding the forelegs.
- Buttocks: (Also "butt" in U.S. English, and "bum" in other English flavors.) Everything from the end of the barrel to the end of the body, excluding the hind legs and tail.
- Arms: The two ancillary protrusions of the upper body, from fingertip to shoulder.
- Forelegs: The two anterior supporting protrusions of the lower body, from the ground to the barrel.
- Hind Legs: The two posterior supporting protrusions of the lower body, from the ground to the buttocks.
- Head/Face: Same as on a human.
- Neck: Same as on a human.
- Upper chest: This refers to the anterior part of the humanoid torso from the top of the upper ribcage to the bottom of the upper ribcage.
- Blend: This refers to the soft anterior part of the body between the upper ribcage and lower ribcage.
- Lower chest: This refers to the ventral part of the body from the anterior end of the lower ribcage to the posterior end of the lower ribcage.
- Loins: This refers to the soft anterior ventral part of the body past the lower ribcage, excluding the hind legs and tail. Similar terminology is used on a horse, but is more of a cylinder on a horse, where I restrict it to just the "under" part.
- Hindquarters: This refers to the portion of the body directly supported by the spine, but anterior to the lower ribcage.
- Saddle: This refers to the dorsal side of the body from the anterior of the lower ribcage to the posterior of the lower ribcage.
- Lower back: The posterior portion of the body between the upper ribcage and the lower ribcage. Mostly the same as on a human.
- Upper back: Same as on a human.
These are mostly as you'd expect. Head, arms, chest, there's not really that much to talk about.
Adult females do have breasts and nipples; but males occasionally will not have nipples. (This is true in some other species, so it's not a huge stretch that vestigial nipples would disappear.)The Blend:
I read an article many years ago arguing various terms for this region of the body, and the word "blend" was the one I liked best, and I've used it ever since. The blend includes what is colloquially called the "belly" or "stomach," as well as the part of the equine body above the start of the equine ribcage.
There is a bellybutton, which is mostly vestigial in my designs, since the stomach is much farther down the body.
The "hips" are not true hips as on a human; rather, they are hints of the uppermost equine shoulder bones, combined with a transition between muscles, and merely look a bit like hips. They move a little with the forelegs during walking or running.
The blend can be classified as "smooth" or "sharp" depending on how the fur grows there; if there is a long transition from bare skin to furred body, it is "smooth," and if there is an abrupt transition at the hips, it is "sharp."The Barrel:
The saddle is named for the object which would sit there on a horse, and allows the word "back" to be used to refer to the humanoid part. Suffice it to say that whether you can actually
put a saddle there depends on the centaur you're talking to.
The withers refers to the rounded lump at the base of the lower back, formed by muscle and fat and the ends of the equine shoulder blades. It may look a little like a hint of the top of a pair of human buttocks, but otherwise has nothing in common.
Most of the remaining terms are fairly normal equine terminology except for the use of the word "fur." Horses have hair on their hides, as do centaurs; but to allow the word "hair" to refer to the long strands growing from the head or tail, the short hair on the barrel and legs I prefer to call "fur."The Legs:
To avoid confusion, arm-like names such as "forearm" are restricted to the humanoid arms. Thus the forelegs especially get a bunch of replacement names.
As there is no reasonable substitute that I can come up with, "shoulder" is used both to refer to the humanoid shoulder and to the equine shoulder.
My centaurs will occasionally use a colloquial term when talking about their legs. "Quarter" is occasionally used instead of "Upper foreleg" (a "quarter" is the joint in the hind leg equivalent to a human knee). "Knee" may become "foreknee" or "hind knee" depending on which legs they're talking about. "Cannon" may be used for the lower foreleg (on a horse, it is usually only for the lower hind leg), and "foreankle" is frequently substituted for "fetlock," the correct term, and "hind ankle" may be used to describe what is correctly just the "ankle." Last, but not least, "hind knee" may be used instead of hock, which is actually quite wrong since it has far more in common with a human ankle than with a knee, but it is likely used for parity with the similarly-positioned joint in the forelegs.
Everybody got that?Other Details:
The bolder blue words here show words that my centaurs would preferably use, right or wrong. The lighter blue words may appear, but are less preferred or considered archaic.Comparison to a horse and human:
In general, the words match up pretty well. "Blend" is new, and "loins" is a little different, and the forelegs need slightly altered names to distinguish them from the arms, but as a whole, if Lucy here said that she'd gotten a splinter in one of her coronets, a horse rancher would know exactly what she was talking about.
So that's basic terminology of the centaur body. Next up, we'll talk about, uh, I dunno, maybe the skeleton or something.