Final answer:
Factors affecting the strength and degree of muscle contraction include the number of myofibers involved and the frequency of action potentials.
Step-by-step explanation:
The strength and degree of muscle contraction are affected by several variables. One important variable is the number of myofibers within the muscle that receive an action potential from the controlling neuron. When the motor cortex signals more neurons in the muscle, a greater number of myofibers participate, resulting in a stronger muscle contraction. Additionally, the frequency of action potentials, or the number of signals per second, can also increase the force of muscle contraction by flooding the tropomyosin with calcium.