It's easy to imagine that a person's forearm is like that of an artist's mannequin: symmetrical and wide below the elbow, and narrowest right at the joint.
It's not, though.
Certain muscles on the lateral side of the joint (the brachioradialis and the extensor carpi radialis longus) begin above the elbow joint on the humerus, creating a bulge which is widest at the elbow, not above it.
Once you see this, you'll draw forearms better.
Tareq Mirza demonstrates his Maya modelling techniques in Organic Modeling I: Human Anatomy Male, an excellent new DVD from Freedom of Teach. Using workflows applicable to any 3D polygon package, Mr. Mirza transforms a box into a clean, well-built virtual representation of Andrew Cawrse's ecorche figure.
You probably will pick up some additional anatomy information here, but this DVD works best not as an anatomy lesson, but as a demonstration of how to think about organic modelling in a polygon environment - it's all about box modelling, controlling edge loops, quad polygon flow, and smoothing. Mirza assumes the viewer has already had some anatomy instruction. For example: When creating the calf muscles, Mirza models the soleus not as a continuous form under the gastrocnemius muscles - as it really is - but as two independent bulges to the left and right of the gastrocnemius muscles - as it appears to be. I'm not suggesting Mirza should do anything different, but a viewer who didn't know anatomy might form a wrong impression of the unseen inner structure of the lower leg. Such anatomy lessons are necessarily beyond the scope of this DVD.
At under $60 Organic Modeling I: Human Anatomy Male is a great value. Freedom of Teach could probably break the chapters on the head and various limbs into their own DVD's and sell each for the price of this entire collection of information. I highly recommend this DVD.
Additional Information:
I've been practicing drawing imaginary faces over skulls.
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Here's a book I found useful in this regard:
Forensic Art and illustration by Karen T Taylor
This is my understanding of how the two most visible heads of the triceps share the humerus.
The lateral head starts fully ON the humerus, and then fully leaves it.
The long head starts fully OFF the humerus, then comes to be fully ON the bone.
The bone seems to travel diagonally under the two muscle heads as they trade places. They don't share the humerus equally.
Los Angeles artist Rey Bustos teaches anatomy from the inside out. I've been taking his class since the new year. Pictured above is my work at about the halfway point. Read on for more...
Santa brought me an a limited edition (2000) resin sculpture of an ecorche figure originally carved in clay by visual effects artist and sculptor Andrew Cawrse, and offered for sale by Freedom of Teach
I have Version 1 (the least expensive one) and in spite of how it may look under this lurid un-white balanced incandescent lighting, the figure is actually very good.
If you're learning anatomy, and aren't quite "getting it" from books alone, this figure is a great additional resource.
Once you become sensitive to the basics of how the human body is constructed, you start to see the same patterns in use in animal anatomy. Since all living creatures on Earth trace their origins to a common ancestor, the same basic patterns arise again and again and again and again. Here's an example:
A human has two bones in his forearm, the radius, and the ulna. When a human rotates (supinates and pronates) his wrist, his radius rolls over his ulna. The relationship between the two bones at the elbow remains unchanged.
A cat (in this case a Sabre Tooth Tiger) needs the ability to manipulate its prey, so it may not surprise you to notice that it, too, has a radius and ulna in its forearms.
Let's take a stroll through the Page Museum at the La Brea Tar Pits and see if any other animals use this mechanism.
Here's a little gallery of images of the bones of the shoulder girdle. I had some trouble gluing the plastic clavicle to the plastic scapula, and I strengthened the joint with a little brass hing mounted 90 degrees to its usual bend axis. In doing so, I lost the little "step-down" from the clavicle to the scapula that artists often point out, but that I seldom see shown in medical diagrams.
The trick to determining the orientation of the upper arm is to locate the condyles of the humerus. The 2 points of the condyles and the "bump" at the end of the ulna form a triangle the shape of which is determined by whether the arm is straight or bent.
There's a few important things worth knowing about the humerus. It's 2 5-eye-lines long. Its shoulder ball joint lies in a different plane to its elbow condyles. The ball joint is marked by a notch through which the biceps tendon passes. The inner condyle is the large one - noticeable on most people.
Here's a small gallery of images of the humerus.
The pelvis, like the skull, and the ribcage, is a major bony structure that doesn't change much regardless of the pose a figure assumes.
Here's a gallery of different views of the pelvis.
Understanding the scapula is an important step in the process of understanding the shoulder girdle. Here's a little gallery of photos of the scapula.
The rib cage, along with the skull and the pelvis, is one of the important, fairly unchanging bony structures of the figure. If you can capture the spine and rib cage, and then hang the shoulder girdles (the scapulae in back and clavicles in front) off of it properly, you've gone a long way toward defining the form of the upper body. Here's my simplified conception of its form.
Learning artistic anatomy? The spine is a good place to start.
Poser has a mode that displays skeletons. The skeletons are not perfect, but they are good enough to use as a muscle anatomy learning tool.
I took my digital camera to a decent plastic skull and made myself a stack of worksheets. Whenever I get a free moment, I grab a sheet and draw what's on it. I try to slip in at least 10 a day.
See that plastic box in the upper righthand corner? It's a disarticulated skeleton. I plan to visit every major bone in the body. Just as an exercise.
The skulls are here if you want to try the same thing yourself.
Thanks to EM-ARTS Digital Printing for graciously offering to host the images.
