Monday, October 3, 2016

Equine Anatomy and Biomechanics: A Primer of Equine Engineering Part VIII, The Head


Here we are again, back to this 17-part series priming us on equine anatomy and biomechanics for the Intermediate student. To start the series, go to Part I.

And that's just it: this is merely a primer. There's so much more to this animal that it would probably lead to a gigantic series! (Which I'm working on as a book series!) But the truth is discovering this information is far more fun than simply hearing it from a blog post. So get out there! Proactively learn more about this critter simply beyond a performance discipline or ideal archetype. Break through conventional knowledge to dig around in the nitty gritty of it all. Science is uncovering new things everyday! 

And it's important for an artist to know all this. In a very real sense, we're beholden to this creature in our art work—we speak for him with the images we choose to convey. If we don't understand what we're "saying," we risk creating problematic images of this fine beast that validate things we wish we hadn't. And that can be upsetting when we later learn the truth.

This is what context does—it provides the framework that allows us to make sounder creative decisions, those that advocate for this animal and align with our convictions. When that happens, we not only gain more confidence, but our art gains authority, and that only leads to a more meaningful creative experience.

So to get the ball rolling, we're going to start our anatomical explorations at perhaps the most obvious place—the head. The equine head is a convoluted series of planes and angles when it comes to artistic re-creation, which is why it's often a trouble spot for many artists. The head is also the part we tend to focus on first, looking for character and anima. Because of this, it's imperative to get the head as correct as possible because one wrong move here can significantly compromise our carefully-crafted illusion of reality. That in mind then, if we understand the underlying anatomy better, perhaps we can gain a better measure of accuracy for our artwork, too.

But before we start, it's highly recommended to read the previous post, Bio-logic, Equine Anatomy 101 before diving more into this series. It has some more detailed information in many areas, and information that primes us for and complements that presented here.

So let's dive in!...

Basic Structure of the Head

Most of the musculature of the head is totally, or in part, subcutaneous. On a thin-skinned, "dry" horse, therefore, much of it is easily deciphered. As a general visualization guide, we can think of his cheek muscles as a "W," laying on its side. In fact, breaking down the horse's head into simple shapes can guide us quite well. To that end, think of the right nostril as a "6," and the left nostril as a backwards "6." The bony zygomatic can be thought of as a "U" for the part blending into the forehead, and as a "Y" for the aspect next to the jaw. Then the nasal bone (when seen from the front) can be thought of as having a slight hourglass shape. Nonetheless, the nasal bone can exhibit a wide degree of undulating characteristics when seen from the side, and are as individualistic as each horse. The upper lip can be thought of as a little box that twitches, pooks, and is actively mobile. The back of the jaw should flow up to the back of the "button" created by the zygomatics, with the ears being positioned right behind that alignment. The lips can be an inversion to each other, with the top one poking out in the corner of the mouth and pinched inward at the front (to blend with the "box" of the upper lip) while the bottom one orients inward at the corner of the mouth to expand outwards at the front. However, this isn't always the case—sometimes they're more or less of equal protrusion.

Some basic visual shapes of the head. Note the alignment of the back of the jaw with the "button" of the zygomatic arch. However, the cheek muscles, or Buccinators, that "W" doesn't always manifest as a "W," but can be a solid wad of flesh or a slightly different configuration, too. It all depends on the individual so pay attention to this area.

The jaw bars form a triangle when seen from the bottom, widest where they meet the jaws proper and narrowest where they meet the chin. They're rounded, not sharply rimmed, and have an underline that represents the individual characteristics of the particular horse.

Some basic proportions and alignments of the head. The blue line represents the ear-eye-nostril alignment. Notice how it runs beneath the ear bulb, the base of the eye, and the base of the nostril.

As a guide, there exists an alignment of under the bulb of the ear, under the eye, and under the lower rim of the nostril. This alignment also represents the axis of the head alignment, or the internal shape of the skull. The axis of the head can be variable dependent on the individual or breed. For instance, Thoroughbreds and Quarter Horses tend to have a straight axis while Arabians generally have an axis bent upwards around the tip of the teardrop bone, or concave. In contrast, Iberian breeds, Kladrubers, Lippizzans, drafters, and others have an axis bent downwards below the teardrop, or convex, producing a "ram head" appearance. (It's believed this head structure allowed horses to carry the long-port bits better because it also results in a more vaulted hard palate.) More or less parallel to this ear-eye-nostril line lays the angle of the mouth and the general lay of the "teardrop" bone of the cheek. These should be considered general guides, however, as each head is different, but these baseline ideas are good starting points for expressing that individuality. 

Here's the ear-eye-nostril alignment (red line). Note how the line of the mouth (blue line) and the teardrop bone parallel this line. Also note how the back of the jaw aligns with the "button" of the zygomatic arches. Used only as a guide, a common mistake with heads is deviating from these template relationships. In particular, we see the jaw line displaced from the "button," either being in front of or behind it. However, each horse is different, so use these alignments as starting points for expressing an individual's uniqueness.

Anyway, from the side, the corners of the eye are angled at an approximate 40-42˚ angle to this ear-eye-nostril alignment. Seen from the top of the head, looking down on it, the eyes are angled more or less at about 33˚ to median, or crease of the nasal bone. The front canthus is seated a snidge deeper than the back canthus. The horse's pupil also tends to stay parallel to the ground, approximately speaking, despite head position, especially when grazing. The upper lid is straighter and the bottom lid is rounded. There often are delicate wrinkles surrounding the eye and lids, which help to forward the idea of soft fleshiness. Overall, the eyes should show intelligence, soul, and character. 

The typical equine head is proportionally divided into thirds: from the base of the ear "V" to the front canthus of the eye, then from that point to mid-head, then from that point to the end of the muzzle. Just remember this is a guide, a template, which should be tweaked to match a breed's or individual's particular head characteristics. But it's a good start to use as comparison.

As for the ears, they're set on the crown of the head, on the sides and are delicately fluted, mobile, and often busy. The "V" where the lower ear rims meet isn't a simple meeting, like two rims of flesh pinched together, but characterized by complex folds, bulges, and twists, especially on the inner rim. 

The eye should be set at an approximate 33˚ angle, give or take for different individuals or breeds.

The shape of the head isn't created by the nasal bone! It's created deep inside the skull with its axis. This is why sculptures that merely change the type of nasal bone without attending to the axis of the head look strange, often appearing too narrow "concave" or "dolphin-like," or too thick (convex). When we compare the different axis angles to the ear-eye-nostril alignment, a concave head will have nostrils lifted above the line and a convex head will have nostrils dipping below the line. The "seahorse" or "dolphin" head can also be created by gouging in a deeper dish and removing more the nasal bone. Sometimes we also see the jaw bars suffering reduction as well, making the head appear fluted, like a chess pawn, or pinched in the middle. Remember, the shape of the head is determined by its internal axis, not its nasal bone.

The ears, anterior lip of the nostrils, and the tip of the nasal bone are made of cartilage. The chin is a pad of fat, making it gooey and smooshable. The muzzle and cheek (the Buccinators) are also fleshy and elastic. The ears, muzzle, and nostril exhibit a high degree of motility and sensitivity, and the brows and lower lid are fleshy and highly expressive (though the upper lid and brow are the most expressive).

It should also be mentioned that facial musculature and configurations can manifest differently between horses, so pay attention to field study and reference photos. (A set of calipers and a protractor are useful tools here.) Each head represents a unique individual, just like us! This isn't to say that the structures are different, however—they're all the same since they're equines. But the construction of the head, especially in the zygomatic and cheek areas, can have some differences in how the cranial musculature is expressed due to individual diversity. So if we recreate the structure of the head the same way on every piece, we risk a formulaic trap. Remember that each face is unique, just like with us.

Skeletal Structure

The equine skull consists of two parts: first, the upper jaw and cranium (the maxilla) and, second, the lower jaw (or mandible). There exists only one joint in the head, that being for the jaw, which is located under the zygomatic arches behind the eye and before the cavity of the ear.

The horse has a long diastema, the space between the front molars and the back of the incisors. This was caused by the "stretching" of the head below the eyes during evolution as he began to adapt to a head-down grazing lifestyle. It's in this diastema that the bit sits.

Within the skull are the hyoids, the important bony system that allows the horse to swallow, which aren't only attached to the areas inside the head and the esophagus, but also to the foreleg. The hyoid bones consist of several bones connected together to form a sling, as follows:
  • Tympanohyoid cartilage
  • Stylohyoid
  • Epihyoid
  • Keratohyoid
  • Basihyoid
  • Thyrohyoid

An adult horse typically has forty basic teeth, or forty-two if we count the "wolf teeth." He has twelve molars, twelve premolars, a set of six of each on either side of the upper jaw and lower jaw. The premolars are in front of the molars. He has twelve incisors, a set of six on the top jaw and another six on the bottom jaw. He has four canines (or "tushes") right behind the incisors. There's also sometimes a first premolar called a “wolf tooth," which is gradually being lost as the horse evolves. It's usually absent in the lower jaw and often absent, or very small, in the upper jaw. The upper jaw is slightly wider than the lower jaw.

The incisors snip the food and the molars grind it up. They are more triangular than the molars, which are more rectangular. Teeth are constantly growing and being worn down, and the pattern of enamel and the shape of the tooth itself can be used to gauge a horse’s age. 

Infant horses have temporary teeth called "milk teeth." They are smoother, shorter, smaller and more white than permanent teeth. Permanent teeth are yellowish, orangish with brown staining, because of the ample enamel, and so they're also tough. They begin to replace the young teeth at about two and a half years of age.

As the teeth grow out, they actually change the shape of the skull. In other words, the deep roots of a young adult's teeth cause the head to be more wedge-like whereas the shallow roots of a senior's teeth cause the head to become more rectangular, or shallow through the jowls. This is one of the reasons why senior citizen heads look so different from the heads of their youth. 

Basic Musculature of the Head

Cranial structure and musculature cannot be fudged—we need to be absolutely clear on its construction to get it right. And if we make a mistake somewhere, most likely this will lead to a systemic problem by skewing everything else. This is because so much about the head is literal, so much being subcutaneous bone and flesh. And it's easy to get confused about the musculature of the head, since much of it is interlaced and woven together. So clarity here is essential. To that end, the basic muscles are:
  • Lateral Ligament of the Jaw: The major ligament of the head.
  • Temporalis: Closes the mouth and helps with lateral motions of the jaw.
  • Buccinator: Presses food back into the mouth and against the teeth when chewing.
  • Orbicularis Oris: Not attached to bone, it forms the shape of the lips. Opens and closes the lips.
  • Depressor labii inferioris: Depresses the jaw or draws it laterally.
  • Levator labii superioris proprius: Either raises the lips or draws them side to side.
  • Transversalis nasi: Dilates the nostrils towards the median, or towards each other on the front of the muzzle.
  • Dilatator naris lateralis: Dilates the nostril laterally.
  • Orbicularis palpebrarum: A sphincter muscle, it closes the eye.
  • Corrugator supercilii: Wrinkles the skin above the eye.
  • Masseter: Closes the mouth in conjunction with the temporalis muscle.
  • Levator labii superioris alaeque nasi: Elevates the nostril and upper lip.
  • Zygomaticus: Pulls the corner of the mouth backwards, towards the eye.
  • Zygomatico-auricularis: Helps to pull the ear forward.
  • Temporo-auricularis: Helps to rotate the ear into the forward, alert position.
  • Nictitans membrane (third eyelid): Removes debris from the eyeball.
  • Caruncula lachrymalis: A small dark pad in the anterior corner of the eye.
  • Eight ear muscles (sometimes nine, depending on the anatomical reference).
Biomechanics of the Head

The jaw can only open at its one joint behind the eye, resulting in the entire jaw dropping accordingly when the mouth is opened. The jaw can only open and close but it has a limited amount of lateral play, as we can see when he's chewing in a rotary motion. When he's chewing, we can also see the cavity behind the eye pop in and out as an expression of the coronoid process of the jaw playing "peek-a-boo." The teeth are large and long, continually erupting to stay in pace with abrasive grass. They take up a significant portion of his skull, but wear down as they grow out (they have a terminal end). This means the shape of the skull changes as the teeth shorten, which is why old horses have a slender, more rectangular head than the more wedge-shaped head of youth. Also, in youth, "tooth bumps" can often be seen on the lower jaw as the roots protrude deeper into the jaw bone, which tend to disappear around 2-4 years of age.

The lips are very mobile, sensitive, expressive, and almost prehensile. The ears rotate around almost 180˚ to listen to sounds, or express alertness with both ears drawn tightly forwards, relaxation when in a "V" formation, or bent backwards and laid on the neck with displeasure. Those are just the basics, however, as the ears are highly expressive of a cascade of emotions. Even so, the ear is usually busy and rich in expression, making it a fun feature to play with in sculpture. The horse is also very expressive with his eyes, as seen with his lids, brows, and brow wrinkles. Actually, his whole face is highly expressive as he can subtly alter the ears, eyes, nostrils, muzzle, lips, and chin, Buccinators, and Masseters to create a host of compelling expressions. 

Also note, despite popular belief, equine eyes not only swivel together (such as to put sclera on the front of back of both eyes simultaneously), but can move like a "cat-clock" as well (with sclera at the back of one eye and in the front in the other eye). They have some independent play. This makes sense for an animal so dependent on vision for survival.

Landmarks and Reference Points

Boney Points of Reference

The skull, being partially made of subcutaneous bone, has plenty of landmarks to guide us. However, the most obvious are the facial crest (or teardrop bone), the boney structures behind the eyes (zygomatics), the nasal bone and forehead, the caudal border of the jaw, and the jaw bars.

We can deduce the last molar because it lies right below the eye and the first molar since it's about midway in the Buccinators.

Some of the easily palpable skeletal landmarks of the equine head.

Fleshy Points of Reference

Because the skull is mostly palatable under the skin, nearly every fleshy facial feature is a landmark. Yet six are stand-outs by being the most consistently present and easily palpated: 

  • Quadratus labii inferioris
  • Depressor labii inferioris
  • Levator labii sup. alaeque nasi
  • Zygoamticus major
  • Buccinator
  • Masseter
The line of the mouth, and the top of the nostril, at the "V" where both nostril rims meet in a fold, are also useful guides as is where the chin ends in union with the visual start of the jaw bars. The bottom bulb of the ear is a useful point to reference to as well as the canthi of the eye. And don't forget the "Y" vein of the face.

The ear-eye-nostril alignment is also a useful template, or at least as a comparison to keep things oriented properly.

Artistic Aspects to Consider about the Head

The head is a strange part of the equine to sculpt. Why? Because having so much of it subcutaneous means that it's both the easiest part to get right, owning to its many landmarks, or the easiest part to get wrong, it being so complicated in structure, proportion, placement, and planing. If we're going to see artistic stylization then, we're going to see it most profoundly in the head.

Because of this, we need to focus on the big ideas first then progress to finer details rather than the other way around, or trying to do it altogether. We also need to keep rechecking our work to make sure those landmarks align. Only when we get enough experience under our belt would we be able to do more simultaneously. 

For this reason, it's probably best for beginners to start with oil clay or ceramic clay so they can do an infinite amount of easy corrections as they learn. Then if they wish to move to epoxies, they should pick one with the longest working time. Only when we're suitably advanced can we tackle the head with rapidly curing epoxies like GapoxioTM.

The smaller the scale, the harder it becomes to sculpt a good head. This is because as scale shrinks, the more important becomes precision and proportion. And as the size shrinks, the size of the sculpting tools becomes more of an issue. Both of these reasons is why many times the head is too big or clumsily sculpted on miniature scales.

When it comes to teeth, each tooth has a distinct shape, as does each group of teeth, meaning the group of incisors and the group of molars. That means we cannot sculpt the same kind of teeth for each tooth or grouping of teeth. We also have to be careful not to make them crooked, asymmetrical  or uneven, too, as that would indicate dental problems. We should also be aware of the age our sculpture depicts in order for it to correspond to the teeth we sculpt. 

When painting teeth, we cannot use plain white but need to temper that with yellows, oranges, browns, and greys to mimic their natural discoloration. Horse teeth definitely aren't pearly white.

Common Artistic Faults with the Head

The head typically has errors in its planing, which is understandable since the equine skull is so complicated with its angles and protrusions. With wrong planing, we can create a head that's too wide and boxy, or zygomatic arches of the wrong orientation and angles, or a head that's too bloated and bulbous throughout. 

Placement is also a problem for the same reason. Sometimes the eye is situated too low or too high, the ears aren't positioned correctly on the crown, often set too far back and high, or the nostrils appear to be sliding off the end of the nose. Often times, the corner of the mouth is incorrectly angled, often dropping off towards the jaw bars. As for the jaw bars, sometimes they can be expressed too knife-thin and sharp rather than rounded, or they're oriented too parallel to each other. More rarely they're too wide apart, causing the head to be disfigured as seen from the front, usually making it boxy and bloated. Also, teardrop bones can be rotated away from their proper orientation, with the tip either pointing too upwards or too downwards in relation to the ear-eye-nostril alignment. Sometimes the back of the jaw doesn't align with the "button" of the zygomatics, often being too far forwards or too far backwards.

When it comes to proportion, the brows are often too big, creating a ghoulish effect with large, overly protruding brow ridges like a Neanderthal. This is usually the case when we get carried away with brow expression. Sometimes, the brows can be too pointed, something that becomes obvious in a three-quarter view. At times, the nasal bone is too narrow or straight and protrudes too high up (not "seated" into the cranium), eyes are far too large, or the nostrils are too big and meaty. Sometimes the flare behind the nostril will simply be a funnel tube lacking the complex dips and curves that indicate the interlacing muscles there. Other times, the head can be unnaturally too broad, too, or the muzzle too small, often paired with a strongly-shaped wedge head, creating an "ice cream cone" head. More rarely, the head is too thin, as seen from the front, beyond the thinness we often see in Iberian or draft heads. At times the sculpting on the head can be clumsy or too extreme, exhibiting slashes and gouges where more fleshy softness is necessary. Other times, the head can simply be too big for the body, which can happen when we become overly focused on it at the expense of the rest of the sculpture. As a general rule, the head, from the tip of the muzzle to behind the ears should be about as long as from the point of the withers to the point of the croup. (The back can sometimes be slightly shorter in stallions making them appear more "square," or slightly longer in mares, making them appear more "rectangular." Sometimes certain breeds aren't faulted for a longish back, such as the Connemara.) Less often, the head is too small for the body. This can make it difficult for the animal to process enough food, water, and air intake for the mass of his body, or present dentistry problems. Similarly, if we sculpt draft horses with muzzles that are too small, we run into the same ethical issues because drafters need hefty muzzles to process all the air, food, and water they need to thrive. Therefore, drafters should have sizable muzzles to accommodate their biological needs.

The ears are a common spot for problems as well. Often times, the ear is set too high or too low, or too far back, almost onto the neck itself. The ears can be too big for the breed or gender depicted, too. In addition, it's an error to simply create a tipped flute pinched at the bottom and then popped onto the head. The equine ear is characterized by nuanced curves to the rims, especially as we get closer to where it connects on the head. When the ear is positioned sideways or backwards, we see these subtle curves more clearly. It's also a mistake to simply pinch together rims to form a "V" at the bottom, where the ear connects to the head. There are complicated folds, twists, bulbs, and curves, especially on the bottom portion of the inner rim, that need expression. At times, but more rarely, the bulb at the base of the ear is missing altogether in sculpture. Furthermore, the complex musculature governing the ears is often ignored, with the ears appearing to be perched on the head rather than set into the head with muscle attachment. Also, mares and foals tend to have proportionally longer or larger ears, respectively. Indeed, we can tell a lot about an artist's observational skills simply by how they sculpt the ears.

A cornucopia of ears. Note the nuanced curves, and the subtle twists, bulbs, and folds at the "V."

Eyes are a common area of misinterpretation, too, often being angled away from the approximate 40-43˚ orientation to the ear-eye-mouth alignment. Or seen from the top, they're oriented too far forwards, like a dog, at an angle well past 33˚, or too flat, like a fish, well below 33˚. Seen from the front, they're also angled too flat on the sides of the head, like a fish, or the lower portion is angled too far outwards, tilting the eye inwards at the upper lid. In reality, the eyeball protrudes slightly farther out at the top lid and more inwards at the lower lid, when seen from the front, so the top brow protrudes slightly farther out than the bottom lid. In addition, from the front, the orb itself may be too flat, again like a fish, rather than rounded. But the equine orb itself isn't round like a ping-pong ball, but oblong and egg-shaped. This impacts how the orb appears within the socket by having more acute curves than a sphere. Eyes are often too big, too, usually because the artist got caught up in expression or the "doe-eyed" look. And lastly, sometimes there's a "trough" carved in between the orb and the lids, from the use of a sculpting tool that was too thick. The lids on horses aren't loose or don't hang like those on a Bassett Hound, but hug the orb tightly.

We also need to be careful with the size and bulging nature of the eye. An eye that's too big and bulging indicates potential hypothyroidism, which is why this affliction is more common in the Arabian than other breeds. The size of the orb is about the same across breeds, too, which is why Drafters appear to have smaller eyes (because of their bigger heads) while ponies appear to have large eyes (because of their smaller heads). It's also the nature of the rims that determines how big the eye will relatively look such as the big round eyes of the Arabian as compared to the more almond-shaped eyes of the Iberian, or the "snake eyes" of the Akhal-Teke.

Nostrils are another problem area, usually being expressed too meatily or bulbous. Sometimes, from the front, the nostrils are sculpted on a straight up and down orientation rather than the upper "V" being angled in more towards the median at the top and more outward away from the median at the bottom. More rarely, the upper "V" will be angled more outwards while the bottom rim will be angled inwards, creating an inverse of what we see in life. It's also a mistake to simply form a meaty tube or funnel for a flared nostril since more often the complex interlacing of muscles cause the flare to have nuanced dips, curves, and configurations. Sometimes, the rims of the nostrils are too sharp, or the front rim that's defined by cartilage is too atrophied or sharp. Instead, the front rim is rounder and larger while the back rim is softly rounded and thinner, but not knife-sharp.

Sometimes heads are made more convex simply by adding an arching nasal bone but ignoring the convex axis of the head itself. So we have a straight ear-eye-nostril line, but with an arching nasal bone. This is an error since a convex head is caused by the convex axis of the head, and not the nasal bone alone. We see the same error with convex heads when a dish has been deliberately cut into the profile without attending to the tweak in the cranial axis. We run into ethical problems with artistic stylization, too, most notably with convex heads such as on the Arabian. A head that's too deeply "dished" will have problems with breathing and dentistry that will compromise the well-being and performance of the animal. Yet we routinely see extreme dishes on sculptures, even absurdly deep dishes. Sometimes we even see heads more like hourglass flutes as the artist tries to amplify "breediness." We need to be careful what we validate, even if we think it's "prettier" because the images we choose to portray have a powerful effect on public sentiment.

Now when it comes to a body of work, heads can be sculpted according to the same formula, overlooking the individual variation typical of the equine head. Most variation tends to occur in the Buccinators and the expression and definition of muscles between the nostril and mouth. The zygomatic arches can also exhibit variation, being softer and more rounded in some horses or more sharply defined and protruding in others. With many stock breeds, the heads can be off-type, or too small. For example, in life, many stock horses have robust heads with the jowls being meaty and comparatively wide, when seen from the front. Quarter Horses also tend to have meatier forehead musculature. The Quarter Horse head also appears distinctly "boxier" than other breeds, and not like the head of a Thoroughbred or Morgan, for instance.

The heads of foals are a common area of misinterpretation as well. The head of the foal isn't simply a smaller, "drier," bonier version of the adult head, but has specific infant characteristics. Broad (often bulging) foreheads, soft zygomatic arches, soft teardrop bones, small muzzles (often with a pouty lower lip and smaller chin), soft jaw bars, smaller undeveloped jowls, large eyes with soft brows, rectangular heads, and big ears are typical. Remember, we're dealing with an undeveloped baby horse, not a mini-adult. On certain breeds, too, the convex or concave nature of the head axis will be present even at infancy, sometimes markedly so. Foals also don't have adult teeth, but "milk teeth," a detail necessary for our foal sculptures with open mouths.

 The brows of a foal are soft and undeveloped.

 Notice the soft, undeveloped nature of the facial features.

 Again, from the front. Note the shape of the head.

Foal muzzles often aren't developed enough to produce those "inverted lips," i.e. the upper corner protruding out and the inner corner sinking in with the front aspect of the lower lips being broader and protruding beyond the "box" of the upper lip.
Photos courtesy of Maria Hjerppe

The heads of senior citizens are also distinctive, having a more slender, rectangular shape due to the shallow, worn-down tooth roots, as mentioned. The "salt cellars" also tend to be deeper, especially if the aged beast's senior nutritional needs aren't being met, causing him to loose too much weight. This can also cause the eyes to lose some of their protruding characteristics as the fat pad behind the eye atrophies, causing the eye to appear a bit sunken in, as seen from the front. Some people confuse this with a "pig eye." This can cause his brows to appear more robust as well as the eye sinks a snidge more into the socket. The head overall tends to become "drier," too, and the muzzle tends to droop, especially the lower lip and chin. 

As we've already discussed, because of the Palantal Drape at the back of the horse's throat, we shouldn't be able to see down his "gullet" if we sculpt an open mouth; we should see the sheet of the Drape instead. However, many open-mouthed sculptures allow us to see down his throat as though the Drape didn't exist. The hard palate is also characterized by specific ridges that are often missing in sculpture; the roof of the horse's mouth isn't smooth. On open mouths, we also often see the "trapdoor mouth" as though the mouth hinged just behind the chin rather than behind the eye. There needs to be a continuous line from the jaw bars to the bottom incisors when the mouth is open. 

As for teeth, often times they're the wrong shape for the group of teeth they represent, or they're inaccurate for the age depicted, in angle, shape, and age-specific details. For instance, having a dark dapple grey on a sculpture with tooth formation of a 20 year old horse is an error. They're also sometimes the wrong number too, or are placed incorrectly. For instance, we may see eight incisors instead of six, or a row is askew to one side. They're often incorrectly colored as well, being pearly white rather than showing the characteristic brown, grey, yellow, and orange discolorations typical of heavily-enameled teeth. Equine teeth also have coloration detail on their crowns which needs attention. 

For more hiccups when it comes to the head, refer to Common Artistic Errors in Realistic Equine Sculpture.

Biological Aspects to Consider about the Head

The equine head's design is one of economy and functionIt's purely functional having neither antlers, horns, tusks nor other such structures, which is appropriate for a large, grass-eating herbivore having to run at sustained high speeds. That means it has very little room for our aesthetic proclivitiesAnd what that means is that our sculpted heads do best when they reflect biological functionality in order to advocate for our subject's well-being. Indeed, the moment we tip into type exaggeration or stylization is when we run into ethical dilemmas. We should also be careful of fads we often seen in type such as Quarter Horses with Arabian-like small heads, Morgans with Saddlebred type heads, or Iberians with Arabian-like characteristics. Fads come and go, and breeders often get off-track, and we do best as the "Grail-holders" of authentic breed type. 

Remember that the head isn't just something we can shape according to our whims. It's an essential component to his biological function and needs to be approached from a functional standpoint first. What we create has an impact on public opinion, so we need to tread carefully. This cannot be overstated enough. Artists have a tendency to get swept up into images or rhetoric without understanding the biological underpinnings of those visuals. We simply can't mold the visual of the horse any way we like...we have rather strict biological parameters to respect (remember the Evolution sub-series?). Indeed, we have a great responsibility with our clay and pigment, so we should think twice before we dive in with "typey" exaggeration. As good equine artists, we first have to be good horsepeoplesomething we should always keep in mind.

Conclusion to Part VIII

That wasn't too bad, was it? Sure, it's a lot to mull over, but it all makes biological sense. And keep in mind that this is just a primer...there's far more to it than this! And that makes it fun! It leaves morsels for us to venture out and find for ourselves, and that lends value and meaning to our experience. In Part IX then, we'll move onto the neck, that wiggley-wobbley thing that can give us so much trouble!

So until next time...get ahead with proactive education!

"An artist must be a reactionary. He has to stand out against the tenor of the age and not go flopping along."
~ Evelyn Waugh

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