An ulcer can be described as an interruption of an internal or external surface which is associated with an inflamed middle or base. Ulcers are usually due to some traumatic event or to some toxin directly applied or produced by a disease process.
Skin-fold callipers. This simple piece of equipment measures the thickness of a fold of skin, most commonly measured below the navel, just below the shoulder blade, above the hip bone
Treatments for ulcers vary, depending upon the epithelial surface that is damaged.
See the relevant ulcer section here, such as Mouth ulcers or Peptic ulcers.