WebMD provides online cross-sectional pictures of the different stages of bed sores. Decubitus ulcers, also known as pressure sores or bed sores, are open wounds on the skin.
Lying down for extended periods of time can cause bed sores, explains Healthline. Thin skin near bone and cartilage, such as the hips, heels and tailbone, are especially susceptible to bed sores. In addition, friction, urine and feces can also cause bed sores. Bed sores begin as discoloration on unbroken skin, and later progress to an open, crater-like sore. The damage then eats away at the flesh under the skin, continuing to muscle and bone.