The obvious and universal symptom of quadriplegia is the loss of function in the legs, torso, and all, most, or some of the arms and shoulders. The body will experience loss of control of digestion, defecation, urination, respiration, and sexual function, as well as a full or partial loss of sensation throughout the limbs. In some cases of quadriplegia, some shoulder, neck, arm, and hand movement will be present, however in the most severe cases there will very little muscle function below the neck. Some cases will be qualified by numbness or no sensation, while some will feature an intense burning sensation throughout the nerves.

Initially, with an average of almost 100 days of hospital stay required with quadriplegia patients, there will be a likelihood of bed sores, atrophy, weak and stiff joints, muscle spasms, lack of reflex, severe blood clots, infections, respiratory complications and failure, and cardiovascular problems. The severity of these additional injuries and symptoms depends on the location of the injury to the spinal cord.

As mentioned on the main page of quadriplegia, there are numerous different grades of quadriplegia injuries that each depend on the affected vertebrae or nerve section in the spine and spinal cord, respectively. For direct injuries to the spine, the grade of quadriplegia is determined by which vertebrae is injured, thus the nomenclature of C-1 through C-8. Injuries affecting the thoracic nerve segments are dubbed T1 through T10, while lumbar and sacral nerve damage are referred to as L1 through L5 and S1 through S5, respectively. As mentioned on the primary page for quadriplegia reference, the symptoms of each injury are:

C-1, C-2, and C-3: These classifications each involve limited head and neck movement based on the muscle strength of each individual, and the person will suffer complete paralysis of the body, legs, and arms. The victim will require assistance in every detail of his daily life, from eating and drinking to changing clothes and getting into bed. Regular travel would be conducted in an electric wheelchair that would be controlled by either a chin control, depending on the neck and head strength, or a breathing straw. The person will require assistance in breathing through a respirator or ventilator, as well as with coughing and clearing blockages of the throat. Speech impairments will require the use of a computer.

C-4: This classification is almost entirely similar to a C-1, C-2, or C-3 injury, in that the victim will require assistance in all daily activities, including washing, dressing, bathroom use, travel, and eating and drinking. The victim also uses a motorized wheelchair that is powered by either chin movement, depending on the muscle strength for head and neck movement, or a breathing straw apparatus. However, the difference between a C-4 injury and a C-1, 2, or 3 is the person will have control of his or her own breathing with a C-4.

C-5: With this spinal injury, the victim maintains head and neck movement, as well as partial shoulder movement depending on the upper body strength of the individual. The body and legs are completely paralyzed, and the wrists and fingers will have no movement, however there will be flexing ability in the elbows and hands. This leaves open the possibility for feeding oneself and controlling menial tasks such as brushing teeth or shaving, with the assistance of special straps. Breathing is done without a ventilator, however all regular daily activities will still require assistance.

C-6: The C-6 injury mirrors most of the aspects of the C-5 injury, including good head, neck, and shoulder strength, however the difference is that the C-6 injury allows additional voluntary wrist and elbow movement. With this injury, the victim can complete some tasks through assistance, such as shaving, brushing teeth, and eating, but can also handled some partial dressing duties. However, all other daily routines require complete assistance.

C-7 and C-8: With these specific injuries, the victim will have no body and leg movement, but good head, neck, and shoulder movement, as well as full elbow and wrist use, and partial finger movement. The person will need partial assistance with most routine activities depending on physical strength and volume of hand and arm movement. Wheelchair travel is a bit easier and with the proper equipment, a C-7 or C-8 victim can even operate a motor vehicle. The main difference between C-7 and C-8 injuries is that C-7 injuries most often allow the use of the thumb.

The injuries that are suffered through thoracic, lumbar, and sacral nerve injuries closely mirror the injuries to each of the vertebrae, depending on where they are located in relation to each other.