The area of skin innervated by a specific spinal nerve is called a dermatome, and the group of muscles innervated by a single spinal nerve is called a myotome. The part of the spinal cord that was damaged corresponds to the spinal nerves at that level and below. Injuries can be cervical 1–8 (C1–C8), thoracic 1–12 (T1–T12), lumbar 1–5 (L1–L5), or sacral (S1–S5). A persons level of injury is defined as the lowest level of full sensation and function. Paraplegia occurs when the legs are affected by the spinal cord damage (in thoracic, lumbar, or sacral injuries), and tetraplegia occurs when all four limbs are affected (cervical damage).SCI is also classified by the degree of impairment. The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), published by the American Spinal Injury Association (ASIA), is widely used to document sensory and motor impairments following SCI. It is based on neurological responses, touch and pinprick sensations tested in each dermatome, and strength of the muscles that control key motions on both sides of the body. Muscle strength is scored on a scale of 0–5 according to the table on the right, and sensation is graded on a scale of 0–2: 0 is no sensation, 1 is altered or decreased sensation, and 2 is full sensation. Each side of the body is graded independently. Complete and incomplete injuries
In a "complete" spinal injury, all functions below the injured area are lost, whether or not the spinal cord is severed.
In 44% of SCI cases, other serious injuries are sustained at the same time; 14% of SCI patients also have head trauma or facial trauma. Other commonly associated injuries include chest trauma, abdominal trauma, pelvic fractures, and long bone fractures.Males account for four out of five traumatic spinal cord injuries. Most of these injuries occur in men under 30 years of age. The average age at the time of injury has slowly increased from about 29 years in the 1970s to 41. In Pakistan, spinal cord injury is more common in males (92.68%) as compared to females in the 20-30 years of age group with a median age of 40 years, although people from 12-70 years of age suffered from spinal cord injury  Rates of injury are at their lowest in children, at their highest in the late teens to early twenties, then get progressively lower in older age groups; however rates may rise in the elderly. In Sweden between 50 and 70% of all cases of SCI occur in people under 30, and 25% occur in those over 50. While SCI rates are highest among people age 15–20, fewer than 3% of SCIs occur in people under 15. Neonatal SCI occurs in one in 60,000 births, e.g. from breech births or injuries by forceps. The difference in rates between the sexes diminishes in injuries at age 3 and younger; the same number of girls are injured as boys, or possibly more.