Anthro leg structure 2

I was asked a few weeks ago to help with creating a set of satyr legs. The main point I outlined was:

only look at the biggest forms when filling out the wire frame with muscles. Keep the curves flowing; show the largest sweeps of these shapes to keep them dynamic; have them show the force of the muscles not just their outlines. Don’t get too hung up on individual muscles at the start, that detail is for later when you’re shading, make sure you’re drawing the big forms to start with.

Some ideas to consider on an unguiligrade biped leg.

Gesture: Centre top is an idea of the flowing curves for a digitigrade and unguligrade type. I wanted to get an idea of the fundamental shapes the curves make as if the legs were mechanical; they would be made of curves that would give them spring as they moved.

Form: On the left an idea of where the muscular bulk is as opposed to the bone and tendon areas. All limbs follow the principle that they get thinner the more distal (further from the torso) they become. Take the human arm as example, muscular bulk decreases further down the arm and the limb becomes more sinuous until we get down to just tendons controlling the hand and fingers. This decrease in muscular bulk is worth noting when drawing so as to keep the limb in proportion. On the right is this idea now shown as contours in the forms of the leg.

Function: At the bottom of the image is a movement sequence. Those areas shaded represent the major muscles that are contracting. The quadriceps, (Q) extend the knee just before the 'contact'. On the 'down', the limb is slowed by the hamstrings (H) as the limb takes the torso's full weight. The elastic energy in taking this weight is channelled down into to fetlock or toe joint by long flexor tendons. This energy is released in the 'up' with the gluteals (G) powering the knee to full extension and the hamstrings extending the hip. This drives the torso forwards as I've talked about in previous posts. Note that the 'knee' and the 'toe' joints flex and extend by the greatest degree, the 'ankle' joint is kept relativity stiff. If the ankle was allowed to flex too much the limb would collapse under the weight of the torso.