Heads Above The Rest!; Exploring The Science and Art Of The Equine Head for Sculpting: Part 8

Introduction

Here we are back again with this 20–part series analyzing the equine head from both an anatomical, evolutionary, biological, and artistic perspective. This is a unique take on this feature since most resources focus on only one perspective, but realism benefits by a grasp of all four because we're not only provided with the whats and hows, but more importantly, the whys for his cranial structure. Thus armed, we can then make more credible creative choices that improve the realism in our work and which also help to steer us away from unintentionally depicting nonviable structure. Indeed, when we know the Biologic behind a structure's evolutionary context, getting it consistent to both nature's blueprint and intentions becomes all the more important.

And fascinating! Learning the backstory of the equine head deepens our appreciation for this magnificent and ancient animal, making what at first seems common place to be revealed as something extraordinary and marvelous. The equine is truly a biomechanical miracle, formed entirely by economical function. What seems to be so simple on the outside then is actually mind–blowingly complicated and multifaceted, and it pays for us to know just how so.

Because know it or not, much about this animal is taken for grated, being so ubiquitous. Even realistic equine artists are guilty of this, typically focusing on getting anatomy right while at the same time overlooking the biological pressures that shaped it. They end up knowing the whats—sure—but not the whys, and it's the whys that lend substance to our compositions. For example, we may sculpt the most technically accurate head, but if we're duplicating nonviable structure, are we really creating according to our convictions? Are we aware of what our creations are saying about our values and knowledge base? Are we slaves to parroting what we see, or are we able to make informed decisions? Do we have the biological facts to defend our choices?

In this Part 8 then, we’ll continue this exploration by discussing his skull which will set us up for the fleshy bits in following installments. So enough jabber, let’s get to it!…

Skull

It might come as a surprise to know the equine skull is comprised of 34 bones, most of them flat. During the birthing process, these bones yield and overlap, allowing the skull to be somewhat compressed for easier parturition. As a newborn, the bones have fibrous joints, which are basically immovable joints where the bones are bound by fibrous tissue, that ossify as the youngster matures.

The equine skull consists of two basic parts—the maxilla (upper jaw and cranium) and the mandible (lower jaw). The maxilla is slightly wider than the mandible and contains the upper teeth, brain case, sinus and nasal cavities, eye orbits, and the ear bullæ. The mandible contains the lower teeth. The cavity created when together is the oral cavity (in the front) and the throat cavity (in the back). From the side, the back of the jaw aligns with the back of the zygomatic arches, in front of the ear, at its “button” underneath the zygomatics.

There’s only one joint in the head, for the jaw, which is located behind the eye, causing the entire jaw to drop when the joint is articulated. The jaw can also open and close with a limited amount of lateral play, allowing the animal to chew in a rotary motion rather than up and down (like we do), or even less so fore and aft. When he chews, the “Salt Cellar,” the cavity above and behind the eye, pops in and out (as do the side cheek muscles)—it’s the coronoid process of the mandible popping in and out of the temporal fossa as synced with the chewing motion. 

When it comes to the maxilla, its bones are grouped into two categories—the cranial bones and the facial bones. Together, they converge to form the orbital and nasal cavities. Specifically, the cranial bones encase the brain and the hearing organs to also include the:

• Sphenoid: A bone that lays at the base of the cranium. 
• Ethmoid: Sits in front of the sphenoid and projects forward to help form the cranial and nasal cavities. 
• Occipital: Located at the back of the skull, commonly referred to as the “poll.” Through it passes the spinal cord into the vertebræ.
• Frontal bones: Lay between the parietals and the nasal bones, forming the forehead and the brow. 
• Interparietal: Found separated only in the horse (and cat), it’s present in other species but fused to its surrounding bones before birth. It lays between the two parietal bones near the front of the occipital bone. 
• Parietal: These two paired bones create the major portion of the roof of the cranium. 
• Pterygoid: Thin, narrow, bent–back plates of bone on either side of the vomer that serve as muscle attachments for throat muscles. 
• Temporal: Creates the sides of the cranium and houses the openings for the ears and the petrosal bones. 
• Petrosal: Contains the ear canal and which isn’t entirely fused to the skull being instead designed to “float” in equines, possibly aiding the maintenance of balance.
• Vomer: A thin sheet of bone in front of the sphenoid that projects forward to divide the posterior nares into two portions.

In turn, the facial bones form the oral and nasal areas while also supporting the structures of the throat such as the tongue, pharynx, and larynx. They’re comprised of the following:

• Premaxilla: Sometimes called the “incisive bone,” it lays in front of the maxillæ and holds the top incisors. It has a plate of two bones (the palatine surface) that project from it into the vomer and the palatine process of the maxillæ, forming the front portion of the hard palate. 
• Orbits: Situated on the sides of the head, the anterior bony portion of the orbit is complete in equines. The supraorbital foramen can be found dorsally, and the foramina for the optic nerve (and other orbital nerves and vessels) are found in the posterior aspect. There’s no post–orbital wall so the orbital floor has a direct opening into the oral cavity, with a barrier provided only by soft tissue—the orb itself sits on a padding of fat within the orbit.
• Lacrimal: Sits in front of the eye and projects onto the face and into the orbit. Its internal surface helps to create the frontal and maxillary sinus cavities. 
• Mandible: The largest bone in the head, it’s the lower jaw which holds the lower cheek teeth and incisors. The two halves are united only by cartilage at birth, which ossifies in about 2–3 months. It has a “body,” the thick front part that seats the incisors and cheek teeth and the “ramus,” the broad portion that bends up into the joint of the jaw behind the eye.
• Maxilla: Forms the side of the face and contains the upper cheek teeth. Its inner portion creates the large surface of the nasal cavity.
• Palatine: The palatine bones of the maxilla create the back portion of the hard palate with the Palantal Drape attaching to its back potion.
• Nasal: Outside where these bones meet, the familiar groove down the front of the head is created while, on the inside, they form the larger portion of the nasal cavity’s roof. They’re long and triangular, and broader on the top and pointed at the bottom. Contributing to the profile of the face, they can exhibit some degree variation in their curvaceous properties and width. They also typically have an hourglass shape when seen from above. However, they're very thin at their tips and can be easily broken if the horse bangs his head there, or tack like hackamores and bosals are improperly used.
• Dorsal and ventral turbinates: Already discussed.
• Malar: Also called the “zygomatic bone,” it lays underneath the eye and entails the facial crest (also called the “masseteric ridge” or “teardrop bone”) and the ridge of the zygomatic arch. The depression made by the zygomatic arches is often referred to as the “Salt Cellar.”
• The Hyoid Apparatus.

The equine skull is a true biological marvel being relatively light, tough, and efficiently functional. Who knew such biological economy could end up being so beautiful and expressive? It's also worth stopping and thinking about just how much weight the neck must support—the average equine head weights about 100 to 120 lbs (45–54kg)! For this reason the head is also a counterbalance and integral part of coordination when it comes to spinal movements and, therefore, gaits, posture, and footfall. In field study then, it's important to pay attention to how the animal uses his head in this way in order to recreate believable compositions.

As for the skull itself, understanding its structures is really important since so much of the equine face is defined by its underlying bony structure, with many parts being subcutaneous. Yet this also gives us reliable landmarks from which to build our heads! So once we've mastered its features and structure, we'll have an essential sculpting guide always at the ready. And that's a handy thing! Because the fact is if we get the skull wrong, our whole head will be off no matter how accurately we sculpt the rest of it. For this reason, developing "X–ray vision" becomes an imperative skill. It's a good idea then to train our eyes with lots of artistic exercises such as tracing the skulls inside of photos and images of our sculpture. And we shouldn't forget to do that for different angles, too!

We also need to be mindful of conformation, or in other words, viable structure. Not all conformation points are created equal! (We have functional conformation, breed conformation, and aesthetic conformation, but more on all that for a future series.) For example, a clenched fist should fit between the jaw bars to provide proper space for the structures and tubes at the back of the head. What's more, head structure isn't a function of taste, but one of viability, of function. So if we treat our sculpted heads with the attitude of "I just prefer it that way," we run the risk of depicting harm if we aren't well–versed in equine biomechanics. For instance, profiles that are too deeply concave, or "dished," or jibbahs that are too pronounced will cause dental problems along with compromised airflow, well–being, and functionality. We'll discuss this and other issues more in a later part of this series.

But suffice to say, skulls vary with each individual animal, too. Not that the skulls are intrinsically different—all horses are part of Equus caballus—but that each skull has unique variations to the blueprint that identify an individual, just like with us. In particular, profiles, width (from the side and from the front, of both the maxilla and the mandible), internal axis, and even orbit placement are all variables. We can't forget the infant characteristics of foals, the "tooth bumps" on 2–3 year olds, the subtle differences between genders, or the changes that happen to the skull as the horse ages, either. Likewise, certain breeds are expected to have rather specific cranial attributes such as dishes, jibbahs, "ram heads," "ox heads," convex or concave integral axes, wedge–heads or rectangular heads, etc. The different equine species such as zebras, asses, and hemonids, and each of their subspecies, also have very distinct skulls that need our careful attention. For example, the occipital ridge of asses is longer, allowing the head to stand end up whereas a horse's skull will fall over because of a shorter ridge. We should also recognize that certain aspects of the skull are anatomical features rather than conformational ones and so aren't so variable. Specifically, the ear bulla, "teardrop bone," teeth and their placement, the joint with the Atlas, and the shape of the rami are all more or less fixed. If we approach each skull with fresh eyes then, we'll be better able to capture all these subtle differences for a much more believable result. Every little tweak contributes to a huge difference!

Conclusion To Part 8

The equine noggin is easily one of the most difficult heads to sculpt in the animal kingdom owning to its nuanced and complicated planes, angles, proportions, structures, textures, variability, and expressions. Being so, it’s typically the area where most artists make the most mistakes. So if we can get our heads more correct, chances are we'll be improving our overall skills to become better at interpreting the rest of the animal, too. In other words, sculpting a good head simply requires more attention and diligence, and that helps us with the rest of what we have to do. In this way, the equine head can guide us to become better sculptors as well as better advocates.

The point then is this: don't take anything for granted about the equine head, especially his skull. It's a finely–tuned, carefully–balanced, precise system formed purely by practicality, starting first with its bony base. As such, most of it is nonnegotiable in biological terms. So one false move can spin our sculpture into portrayals we may not intend, so care and practiced technique are essential. For this reason we should, at the same time, regard all points of type with a critical eye. Indeed, we not only have to think about the presence of the desired features themselves, but the degree to which they're expressed and the nature by which they're formed. There's a lot to weigh and juggle here so being equipped to mediate these issues with biological data helps us to build an artistic sensibility that's more consciously aligned to our values. In turn, we affirm our Voice and the nexus of our aesthetic, and that leads to stronger work. In so many ways, the equine head offers us so much! So curious that through all the millennia of convoluted equine evolution, we could come to a point in our own fleeting lives where nature's ancient serendipitous design could help us in so many ways. Until next time then…get ahead and go extra mile to get things right!

“An artist is an explorer. He has to begin by self–discovery and by observation of his own procedure. After that he must not feel under any constraint.” ~ Henri Matisse