A lower motor neuron injury primarily causes which type of paralysis?

A lower motor neuron injury is characterized by damage to the motor neurons that originate in the spinal cord and extend to the muscles. This type of injury leads to flaccid paralysis, which is a condition where the affected muscles are weak and cannot contract properly. The hallmark of flaccid paralysis is muscle hypotonia, where the tone and strength of the muscles are significantly reduced.

In the context of lower motor neuron injuries, the inability to properly stimulate muscle contraction results in a lack of muscle tone and strength. Additionally, individuals may experience muscle atrophy over time due to lack of use. Common causes of lower motor neuron injuries include trauma, diseases such as polio, and conditions affecting the peripheral nervous system, leading to these typical signs of flaccidity.

In contrast, spastic paralysis occurs as a result of upper motor neuron injuries, where there is increased muscle tone and exaggerated reflexes. Mixed paralysis can involve both lower and upper motor neuron characteristics, and absent paralysis is not a recognized type within this context. Thus, the association of flaccid paralysis with lower motor neuron injuries is clear and well-established in neurological and rehabilitative contexts.