you're mostly right, but don't neglect the shape of the tibia, is has a built-in ridge even in the most pefect examples which does bow out and the profile of which can easily be felt. the strong devision there in the sketch between light and shade is not an illustration of the fibula, but of that ridge.
in the end what it comes down to is being able to observe the way contour and light changes over the form and figuring out how it will change when the form moves. for the shin, the important part is not necessarily whether the bowing is due to the tibia or fibula, but that the bow is a constant because it is defined by a bone. the calf on the other hand will change size and position based on the movement of the leg. the adductors are quite visible when the figure stands with the leg closed, but open they smooth out almost completely. under the hip, your gluteus medius (occasionally called the hip adductor) along with the tensor wrap around the hip and create a soft form between the hard crest of the hip and the hard top-point of the femur. the sartorius, the only function of which is to assist all other functions, wraps around and adds a predictable irregularity to the vastus muscles (favoring the inner bottom and the upper middle for form. the kneecap in a standing position sticks out from the lower point of the femur, but in a bent-knee position is more or less a smooth extension in the direction of the upper leg while the tibia and fibula drop.
my point - it's not really helpful to learn what a leg looks like because it changes so much. what's best is to learn why it looks like that so that you can construct the basic forms of it without reference and, more frequently in a game-oriented world, in stylization and abstraction (things i still struggle with).