The head-end of the artist’s motor nerve, the body of the nerve cell, is connected to a cluster of structures called synapses (figure 8.2), which are kind of nerve-to-nerve junction boxes. Upstream nerves release neurotransmitter molecules into these junctions much as neurotransmitters are released at the nerve–muscle junction; this triggers the opening of ion channels in the membrane surrounding the nerve cell body, thereby allowing positively charged ions to rush inside, causing its voltage to drop sharply.
