What type of injury would most likely require a tourniquet?

A tourniquet is specifically designed to control severe bleeding, especially from major arterial injuries in a limb. When there is significant blood loss that poses a life threat, applying a tourniquet can help to effectively occlude blood flow and stabilize the injury until further medical care can be provided. This is particularly critical in traumatic scenarios where rapid intervention is necessary to prevent exsanguination.

Injuries such as a bodily fracture may not necessarily lead to severe bleeding unless they are compound fractures where the bone pierces the skin. Minor lacerations, by their nature, do not typically produce the kind of life-threatening hemorrhage that warrants the use of a tourniquet. A concussion involves traumatic brain injury and does not relate to limb injuries requiring hemorrhage control. Therefore, the use of a tourniquet is primarily reserved for cases of severe bleeding from a limb, making it the most appropriate response in this context.