There’s a list, and a rule behind it. Pressure sores tend to form where skin covers bony areas with less tissue under the skin to pad the area.
The usual places are the buttocks, elbow, hips, heels, ankles, shoulders, back, and the back of the head.
The back of the head is the one most people leave off, and the heels are the ones most often missed in practice because they’re out of sight under bedding.
The rule is more useful than the list, because it tells you where to look on a particular person. Wherever a bone is close to the surface and bearing weight is where the pressure falls, and that changes with how someone sits or lies.
The looking should be deliberate and daily. Check your skin for pressure sores every day, and ask your caregiver or someone you trust to check areas you can’t see. Most of the list isn’t visible to the person themselves.
At the earliest stage, you’re looking for a reddened, painful area on the skin that does not turn white when pressed, which is a sign that a pressure ulcer may be forming. Or an area that is dark purple or maroon, which is a deep tissue injury that can quickly become a stage III or IV sore.
Position decides which sites are at risk. The repositioning intervals are different for the two main situations: about every 2 hours in bed, and every 15 minutes in a wheelchair.