Spinal cord injury: definition

What is the spinal cord?

brain extension

The spinal cord is the extension of the brain through the spine and allows the flow of all nerve messages between the brain and the rest of the body.


Regulate certain reflexes (for example when one withdraws his hand from a hot cooking plate, directly without passing nerve information to the brain)


Transmit motor information to the muscles. It is made up of nerve fibers that relay sensory or motor information, as well as neurons specific to the spinal cord


Transmit sensory information to the brain

Anatomy of the spinal cord

The spinal cord is part of the Central Nervous System. It is made up of 24 vertebrae (plus 9 fused sacro-coccygeal vertebrae): 7 cervical vertebrae C1-C7; 12 thoracic T1-T12; 5 lumbar L1-L5

The spinal nerves are connected to the spinal cord. They are responsible for the motor skills and sensitivity of the limbs, sphincters and perineum. Each spinal nerve is formed by the union of two spinal roots, one dorsal sensory and the other ventral motor.

These spinal nerves transmit information from different levels of the spinal cord depending on their position in the spine:

8 cervical nerves (C1 to C8)
These nerves located in the neck provide mobility and sensitivity to the upper limbs, neck, upper chest and diaphragm.

12 nerfs thoraciques (T1 to T12)
These nerves on the upper back provide mobility and sensitivity to the trunk and abdomen.

5 lumbar nerves (L1 to L5) + 5 sacral segments (S1-S5)   
Located in the lower part of the back, these nerves provide mobility and sensitivity in the lower limbs as well as the function of the bladder, bowels and sexual organs.

Spinal cord injury: explanations

The spinal cord injury, or "spinal cord injury" can have multiple causes: accidents of life or disease can be responsible for these injuries. 

An injury to the spinal cord can cause paraplegia (paralysis of the lower limbs) or quadriplegia (paralysis of the lower and upper limbs) leading to sensory and motor losses but also genito-sphincter disorders. The messages that the brain wishes to transmit to motor and sensory functions no longer pass, or pass badly.        

Take the example of a highway: if it is bombed, a crater forms and prevents vehicles from moving in both directions. Then create a traffic jam or a strong slowdown.



We always believed that it was possible to fix this traffic lane by building a bridge to keep vehicles moving again: that the information between the brain and the rest of the body flow again.     

This lesion causes a more or less significant loss of mobility or sensitivity. Depending on the neurological level of the spinal cord involvement and the extent of the injury, different functions will be affected. There are two types of spinal cord injury: complete injury and incomplete injury. With a complete lesion, the paralysis affects the entire part of the body below the lesion. In the event of an incomplete injury only part of the spinal cord is damaged. In this case, some of the mobility or sensitivity may be retained.

Associated disorders

- Pain
- Sphincter, bladder and intestinal disorders.
- Genital-sexual disorders.
- Respiratory disorders.
- Stiffness called spasticity which causes pain. 
- In some cases, complete disappearance of tone which is the cause of significant muscle wasting and other associated disorders.  
- In case of cervical and upper back injury: sufferers suffer from hypothermia in a cold environment because their body is not able to transmit the signal to cool the body to the brain. The high heat is also poorly tolerated because spinal cord injuries do not sweat below the level of the injury, which prevents the body from cooling down properly. 

Science is evolving day by day: over 10 years ago, we thought it was impossible to repair a spinal cord injury by believing that neurons could no longer grow back after being severed. However, we have proven that it is otherwise. The human body is a wonder!