| Impairment | A loss, alteration or abnormality of psychological, physiological or anatomical structure or function. |
| Inferior | Lower in position. |
| Inflammation | A reaction of soft tissue due to injury that may include malfunction, discomfort, rise in temperature, swelling, and increased blood supply. |
| Initial Intensive Care | A type of chiropractic care characterized by frequent visits for the purpose of eliminating or reducing the major complaint. |
| Interference | Damage or deficit to the nervous system. |
| Intervertebral Disc | Fibrocartilage padding between vertebral bodies that act as a shock absorber, with a pulpy center that acts as a ball-bearing. |
| Intervertebral Foramina | The lateral opening through which spinal nerve roots exit the spinal column. |