Which statement correctly defines lower motor neurons?

Which statement correctly defines lower motor neurons?

• A. Interneurons within the spinal cord.
• B. Neurons in the brainstem that coordinate eye movements.
• C. Neurons with cell bodies in the posterior horn that sense touch.
• D. Motor neurons with cell bodies in the anterior horn of the spinal cord that innervate muscle fibers.

Answer: (D)

Lower motor neurons are the final pathway that carries commands from the CNS to skeletal muscles. Their cell bodies reside in the anterior (ventral) horn of the spinal cord (and in motor nuclei of the brainstem for cranial nerves) and their axons extend out to innervate muscle fibers, triggering contraction. This direct connection to muscle fibers is what defines them as motor neurons that execute movement. The statement that best fits this definition describes motor neurons with cell bodies in the anterior horn of the spinal cord and that innervate muscle fibers, capturing both their location and function. Other options refer to interneurons within the spinal cord, brainstem circuits for coordinating eye movements, or sensory neurons in the posterior horn—none of which describe the cells that directly innervate skeletal muscles.

Lower motor neurons are the final pathway that carries commands from the CNS to skeletal muscles. Their cell bodies reside in the anterior (ventral) horn of the spinal cord (and in motor nuclei of the brainstem for cranial nerves) and their axons extend out to innervate muscle fibers, triggering contraction. This direct connection to muscle fibers is what defines them as motor neurons that execute movement.

The statement that best fits this definition describes motor neurons with cell bodies in the anterior horn of the spinal cord and that innervate muscle fibers, capturing both their location and function. Other options refer to interneurons within the spinal cord, brainstem circuits for coordinating eye movements, or sensory neurons in the posterior horn—none of which describe the cells that directly innervate skeletal muscles.