The Injury Severity Score (ISS) is an established medical score to assess trauma severity. It correlates with mortality, morbidity and hospitalization time after trauma. It is used to define the term major trauma.
The Abbreviated Injury Scale

Abbreviated Injury Scale

Abbreviated injury scale is an anatomical-based scoring system to determine the severity of single injuries based on the survivability of the injury. AIS is one of the most common anatomic scales for traumatic injuries...

 (AIS) is an anatomically based consensus-derived global severity scoring system that classifies each injury in every body region according to its relative severity on a six point ordinal scale: 1 Minor, 2 Moderate, 3 Serious, 4 Severe, 5 Critical, 6 Maximal (currently untreatable).

There are nine AIS chapters corresponding to nine body regions: 1 Head, 2 Face, 3 Neck, 4 Thorax, 5 Abdomen, 6 Spine, 7 Upper Extremity, 8 Lower Extremity, 9 External and other.

The official website for (AIS) is http://www.aaam1.org/ais/.