Question

I decided not to include "part of the CNS" and "part of the PNS" as possible answers to the previous question ("NS classification I") because I thought that might make the question too tricky. Which of the following is a true statement that explains why those would have been tricky answer choices?

A. Because alpha motor neurons have parts in both the CNS (their axons) and the PNS (their cell bodies) but the cells are not entirely found in either division.

B. Because alpha motor neurons synapse onto muscles, so they are not considered a part of either the CNS of the PNS.

C. Because alpha motor neurons have parts in both the CNS (their cell bodies) and the PNS (their axons) but the cells are not entirely found in either division.

D. Because alpha motor neurons are a part of the autonomic nervous system, so they are not considered a part of the CNS or the PNS.

Answer 1

Option C is the correct answer.

Alpha motor neurons are large multipolar neurons originated from brain stem and spinal cord. Theses neurons innervate skeletal muscles and thus are directly responsible for muscle contraction. Although these neurons belong to brain stem and spinal cord (part of CNS) because of presence of their cell body in these regions, their axons are extended to the peripheral nervous system to innervate the skeletal muscles.

Note: Skeletal muscles belong to somatic nervous system which is the part of peripheral nervous system.