Cutis anserina: Better known as goose bumps, a temporary local change in the skin when it becomes rougher due to erection of little muscles, as from cold, fear, or excitement.
The chain of events leading to this skin change starts with a stimulus such as cold or fear. That stimulus causes a nerve discharge from the sympathetic nervous system, a portion of the autonomic (involuntary) nervous system. The nerve discharge causes contraction of little muscles called the arrectores pilorum (the hair erector muscles). Contraction of these muscles elevates the hair follicles above the rest of the skin. And it is these tiny elevations we perceive as goose bumps.
Goose bumps are also referred to as "gooseflesh." Another for this familiar phenomenon is "horripilation." Medicine has a special term, "cutis anserina" for goose bumps. But it goes back to the goose again, since "cutis", skin + "anser", goose = goose skin.
Some biologists believe that goose bumps evolved as part of the fight-or-flight reaction along with heart rate increases that send the heart racing while blood rushes to the muscles to give them additional oxygen. A similar phenomenon, bristling, in fur-covered animals may have made them look larger and more frightening and kept them warmer by increasing the amount of air between hairs which traps body heat.
