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Basic big cat anatomy tutorial

 

All cat's anatomy is completely dictated by how it hunts. Studying how the cat you want to draw hunts will help in understanding its anatomy .

The only way to learn good anatomy is to study the subject, the skeleton, the muscles and what it looks like moving in real life. Here is an example of some of my studies. On the left is a page of 1 minute drawings done from real life and on the right is a page of 1 minute drawing movement sequence taken from a slowed down video. Study in zoos, pictures and videos to see how the body and muscles change shape and what bones show through when the animal does various activities.

So, how do we draw the animal from our head? We already know that the bones themselves don't change length or move except where there is a joint and create the animal's pose so we draw these first. Start off with the major masses, the head, ribcage and hips. connect up with the neck and spine.

Notes-

1. The tail is an extension of the spine, not a separate object so make sure it flows from the spine line.When posing it remember it acts as counter balance so will go in the opposite way from the weight. The line of the spin will help place this.

2. The neck feeds into the top (base) of the skull *see red star* There is a lot of muscle at the base of the skull and in the neck making it very big and strong, enabling a stronger bite and the power to cling onto and pull down prey with the head/ mouth.

How to work out the proportions. If we grid a big cat that catches its prey by stalking we can see that the height of the body is that same as the height of the legs. Also the body's length is double the ribcage area.

Note-

3. a cat that catches its prey a different way from stalking will have different proportions *covered later*. Very large cats such as male tigers and lions have even larger bodies and shorter legs. almost 2/3 body, 1/3 leg height. Proportions vary between genders too.

Oke, lets have a closer look at the legs. In this picture we have a front leg on the left and a hind (back) leg on the right. We can see the cat walks on its toes/ fingers (phalanges) on all feet. We can also see that the metatarsus bones are longer versions of our palm/ foot bones. This makes the wrist and ankle joints higher off the ground.

The back leg is very similar to our own, try going on tiptoe and that's exactly what the cat is doing. The difference being the pelvis which is almost horizontal rather than vertical and a different shape.

The front leg is similar to our arms however you can see that the shoulder blade hangs on the side of the ribs. This makes the cat narrow across the shoulder. One of the most important feature is the Ulna and radius bones. The radius can rotate round the ulna allowing the wrist to twist. You can see this working when you turn your own hand. Two reasons that we need to know about this-

1. As the bones rotate, the arm/ leg shape changes both in profile and in musculature. It also makes up the wrist and affects the hand/ paw position.

2. The amount of flexibility varies according to species. A cat such a leopard or Margay which are excellent tree climbers have the most flexible wrists, (that is how they can climb trees), But an cat that chases things such as a lion has a much less flexible wrist as this makes it stronger for running, however this means they're very poor at climbing trees. A cheetah that is built to run has the least flexible wrists.

We don't need to draw all that detail though. We can simplify it like this.

Note-

4. Again the angles on the bones (how bent the legs are) vary between species. A stalking cat will have quite acute angles (very bent legs) to help it creep and keep it lower to the ground. A tiger that uses ambush in higher growth has less acute angles in its legs and the cheetah and caracal's legs are very straight *covered later*

Now we have the structure, we can flesh it out. Again this outline will be different between species. Most animals as built so that the frown legs takes the weight of the animal and the back legs provide the propulsion (speed). Because most cats hunt by stalking or ambush big cats are heavily muscled around the front legs to give it the strength to pull down large prey and to drag the carcass. (once more, the exception of cats like cheetahs and caracals)

From the simple keeling drawing we can see where the bones would show through *blue* and from this and in depth real life study we can work out where the main muscles are.

Oke, now for the pesky cheetah! Doing the grid on it we can see that the legs are slightly longer than the body height and the body length is slightly longer too. The extra body length helps it run by allowing the spine to flex more.

Now the leg bones. Unlike the previous stalking cat, the cheetahs legs are very straight and the spine is more curved enabling it be high off the ground, increasing the size of its pace and to run very fast.

The outline. Its is different from the previous cat in several ways. The chest is deeper and the waist is very slim. The neck, body and tail is longer and head smaller. The legs are much slimmer including the front as it trips its prey and suffocates it rather than using the strength of its forelegs, neck and jaw to catch its prey. Both the shoulders and the hindquarters are well built. As previously mentioned, the propulsion comes from the hindquarters so like a good racing horse has a large muscular back end, so does the cheetah. The shoulders. chest and neck flow more smoothly in to each other creating a larger visual mass.

Next, the chest front view which i know some people struggle with. Start with the basic proportions and masses.

Now add the leg bones. From the front, the angles almost disappear however there is still the shape and curvature of the muscles so they don't become flat. It helps to curve the lines rather than drawing them straight.

The neck obscures part of the shoulder muscles and also has its own muscles that feed in so put that in next. Also add the pectoral (chest) muscles at the top of the legs where the shoulder blade finishes jutting forward and joins the humerous.

Finish the rest of the muscles and outline. Studying will really help with knowing where the muscles are. The back leg looks almost straight with just a few muscle bulges.

The chest is something that does vary a lot too between species. The leopard on the right has its shoulder blades further back to the sides so it can climb better. It had much more muscle around its shoulders and has a notable gap between the pectoral muscles where there is the breastbone as the legs are further apart.

The cheetah on the left has its shoulder blades much further forward and closer together. This means its slimmer so its more streamlined and can reach further forward.

Note-

5. Head shape varies too between species so watch the details on it. Try and study and compare as many different cat species as you can!

 

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