UPMC Rehabilitation Institute

Spinal Cord Injury Basics

The spinal cord connects the base of the brain to the body’s nerves, making it an important communication highway between the brain and the rest of the body.

It is surrounded and protected by a bony canal, which is part of the spinal column (also known as the spine or backbone).

A spinal cord injury happens when the spinal column fractures or when the ligaments holding the spinal column together fall out of alignment. As a result, the spinal cord within the bony canal may be bruised or crushed.

This injury interrupts the communication between the brain and the parts of the body below the site or level of injury.

  » Learn more about the anatomy and physiology of the spine.

What is a Level of Injury?

The level of injury:

• Refers to the point where the spinal cord is injured.
• Marks a border between areas of the body that are affected and not affected by the spinal cord injury.

Spinal cord levels of injury are named according to the corresponding vertebra and spinal nerve exiting from the spinal canal in that area.

For example, you may hear your doctors talk about a C6 level. This means the spinal cord is injured at the level of the backbone’s sixth cervical (neck) vertebra.

Muscles and other organs:

• At and above the level of C6 still have nerves connected to them.
• Below C6 have lost communication with the spinal cord and brain.

Likewise, injuries at the:

• T9 level correspond to the ninth thoracic (chest-level) vertebra
• L2 level corresponds to the second lumbar (lower back) vertebra

For more information on levels of spinal cord injury, visit:

• Paralyzed Veterans of America
• Spinal Cord Injury Information Network from the University of Alabama at Birmingham

Abilities After Injury

Your abilities after you're injured depend on the level of injury.

The extent of the injury also changes from person to person. It depends on which parts of the spinal cord are injured and how badly the cord was injured.

• Some people can move their arms, but cannot feel light touch or pinpricks.
• Other people have sensation, but no movement.
• Others may have no sensation and no movement.

Complete and Incomplete Injuries

There are complete and incomplete spinal cord injuries.

Testing Spinal Cord Injuries: The ASIA Exam

An American Spinal Injury Association (ASIA) exam is a standard physical to help:

• Determine which parts of the body are working normally and which parts are affected by the spinal cord injury.
• Classify the level of your spinal cord injury.
• Predict your recovery from the injury.

The exam is extensive because it covers the whole body. A physician trained in performing the exam will test strength and sensation.

Motor Exam

• The motor exam tests five key muscles in each arm and leg.
• There are 20 key muscles that are tested overall.
• Each key muscle corresponds to a level in the spinal cord:
  • a C5 level corresponds to bending the elbow
  • an L3 level corresponds to straightening the knee

Sensory Exam

• There are two parts of the sensory exam: light touch and pinprick. Light touch and pinprick are tested separately because they travel in different nerve pathways in the spinal cord.
• Each spot on your skin corresponds to a level in the spinal cord:
  • sensation on the tip of your middle finger corresponds to C7
  • sensation behind the knee corresponds to S2
• The pinprick pathway travels closer to the motor pathway than the light touch pathway.
• Recovering sensation in the pinprick pathway can better predict recovery than light touch in the motor pathway:
  • If you have normal light touch sensation at the tip of the finger, the chance of getting strength back in the muscles that straighten the elbow would be about one in 10.
  • If there were normal pinprick sensation at the tip of the finger, however, the odds of getting strength back to the elbow muscle group would be at least six in 10.

Anal Muscle

• This is an important last step in the ASIA exam.
• The very end of the spinal cord sends motor signals to the external anal sphincter, which is the muscle that contracts when the patient is trying to hold a bowel movement. The same nerves that control that muscle send light touch and pinprick signals back to the spinal cord.
• The physician will ask you whether you can feel pinprick and light touch in the anal area. You also will squeeze the physician’s gloved finger when it is inserted in the rectum.
• If the motor and sensory functions are intact on the rectal exam, the injury is incomplete.
• If you cannot contract the anal muscle and cannot feel light touch and pinprick, the injury is considered complete.