Student or Learner
"Where the subcutis and dermis are attached to the underlying fascia and cannot stretch or slide over the tissues, flexure lines occur."
What do "stretch over" and "slide over" mean in this contex? That they cannot move? Or cannot cover the underlying tissues?
Those lines on your knuckles (where your fingers bend) are called "flexure lines." You have similar lines on the palms of your hands and on your elbows. The dermis (lower layer of skin) is actually attached to an underlying structure in the body, which holds it in place. It cannot move from side to side ("slide") or up or down ("stretch") as the dermis can in other areas of your body (for example, the back of your arm). Because the dermis is held firmly in place, flexure lines (or wrinkles) develop in those areas.