Which statement best describes lower motor neuron lesions?

Which statement best describes lower motor neuron lesions?

• A. They primarily affect brain function
• B. They cause hyperreflexia
• C. They cause flaccidity
• D. They are limited to the autonomic system

Answer: (C)

Lower motor neuron lesions disrupt the final pathway from the spinal cord to the muscle. When this pathway is damaged, muscles lose tone and strength, leading to flaccidity. Reflexes are reduced or absent, and muscles often atrophy with possible fasciculations. This contrasts with upper motor neuron lesions, which produce increased tone (spasticity) and hyperreflexia due to loss of cortical inhibition. Autonomic involvement isn’t the defining feature here, as LMN lesions primarily affect somatic motor output to skeletal muscle. So describing LMN lesions as causing flaccidity best reflects the hallmark change in the affected tissue.

Lower motor neuron lesions disrupt the final pathway from the spinal cord to the muscle. When this pathway is damaged, muscles lose tone and strength, leading to flaccidity. Reflexes are reduced or absent, and muscles often atrophy with possible fasciculations. This contrasts with upper motor neuron lesions, which produce increased tone (spasticity) and hyperreflexia due to loss of cortical inhibition. Autonomic involvement isn’t the defining feature here, as LMN lesions primarily affect somatic motor output to skeletal muscle. So describing LMN lesions as causing flaccidity best reflects the hallmark change in the affected tissue.