Skins come from calves, foals, sheep, goats, and other small animals (young camels and seals). Hides are the skins of cattle, horses, donkeys, camels, deer, elk, walruses, and whales. Pigskin raw materials are the skins of domestic and wild swine. In addition to these most important types of leather raw materials, the skins of reptiles (crocodiles, lizards, and snakes) and fish (wolf-fish, cod, burbot, sheatfish, dog salmon, giant sturgeon, and shark) are also used.
If x-rays are normal, an MRI or bone scan is a more accurate way of diagnosing a stress fracture. The area where stress fractures of the hip occur is called the femoral neck. This is where the hip joint connects to the femur (the thigh bone).
Following the basic premises of continuum mechanics, stress is a macroscopic concept. Namely, the particles considered in its definition and analysis should be just small enough to be treated as homogeneous in composition and state, but still large enough to ignore quantum effects and the detailed motions of molecules.