10. 2 somatic nervous system: the somatic nervous system regulates the activity of skeletal muscle. Voluntary control from cerebral cortex, with contributions from the basal nuclei, cerebellum, brain stem and spinal cord. Posture, balance, breathing, and somatic reflexes(such as the flexor reflex . ) are involuntarily controlled: a somatic motor pathway is comprised of a somatic motor neuron and skeletal muscle, the nmj is the site where a somatic motor neuron communicates with a skeletal muscle fiber. Epp*(end plate potential) is a type of graded potential that is similar to an excitatory postsynaptic potential(epsp). Epp has larger amplitude(size) than epsp because there are more neurotransmitter receptors in the motor end plate and a larger number of ion channels open. So a single epp typically is large enough to depolarize a muscle fiber to threshold: the events at the nmj can be altered by chemicals name botulinum toxin.