Motor neurons 1 and 2 start out innervating the same number of muscle fibers in a neonatal mouse. If motor neuron 1 releases more acetylcholine in the first two weeks postpartum, ultimately:
A) motor neuron 1 will innervate more muscle fibers.
B) motor neuron 1 will have a thicker axon.
C) motor neuron 1 will be activated prior to motor neuron 2 during muscle contraction.
D) a and b
E) a, b, and c

Question

Quizplus · Accepted Answer

The more competitive axon should 'win' control of more muscle fibers, and axon diameter correlates with number of muscle fibers innervated. However, smaller motor neurons activating fewer muscle fibers become activated before larger ones activating more muscle fibers.

Motor Neurons 1 and 2 Start Out Innervating the Same