When the spinal cord is damaged at a specific segment, all segments below the injury site are cut off from the brain, leading to paralysis in those corresponding areas. As a result, the lower on the spine the damage occurs, the fewer bodily functions the injured individual will lose.

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Spinal cord injuries disrupt the communication pathway between the brain and the body. When a specific segment of the spinal cord is damaged, all segments below the point of injury are disconnected from the brain, leading to paralysis. The nature of the paralysis and reflex activity can vary; complete severance may cause flaccid paralysis and a loss of reflexes, whereas injuries where the tissue remains intact can lead to abnormally strong reflexes due to the loss of inhibitory signals from the brain.

Spinal Cord Injuries

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

- Inserting stem cells that will differentiate into neurons, project axons over the break 
- Transplanting glial cells (ex. olfactory ensheathing cells) to guide axon growth across the break 
- Introducing neurotrophic/ cell adhesion molecules to promote axon growth across the break for surviving neurons 
- Transplanting peripheral neurons to form a bridge around the break and connect the brain and lower spinal cord. Peripheral neurons are chosen as they uniquely have the ability to regrow and reconnect with their targets

Spinal Cord Injury Treatments

- Virus caused destruction of motor neurons in the spinal cord, or even the cranial motor neurons in the brain stem (such as poliovirus) can cause atrophy of the muscles which no longer receive input from the neurons 
- This may necessitate a ventilator if the muscles controlling breathing are targeted 
- In amyotrophic lateral sclerosis (ALS) there is spontaneous death of motor neurons in the brainstem and spinal cord, causing the affected muscles to "waste away"
- ALS causes increasingly worse paralysis, eventual loss of skeletal muscle function, and typically a premature death 

Motor Neuron Destruction and Death/ Motor Impairment

Two individuals sustain injuries at the same level of their spinal cords. Individual A's spinal cord is completely severed, while Individual B's spinal cord is damaged but the neural tissue remains physically connected. Based on the typical physiological responses to these types of injuries, what is the most likely difference in symptoms observed below the point of injury?

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