Chemical synapses

Most of the signaling between nerve cells occurs through chemical synapses. These are created by the close association of an axon terminal of the presynaptic cell with a few part of the postsynaptic cell. The gap between the cells, the synaptic cleft, is usually 20 nm across though in various synapses can be much wider. The Synapses are classified by where on the receiving cell they are positioned. Most are axodendritic synapses made on dendrites; onspiny dendrites synapses are formed on spines. Mostly powerful are axosomatic synapses made on the cell body (named for an alternative word for the nerve cell body,the soma). The Synapses between axon terminals and axons of postsynaptic neurons are axoaxonal synapses.

                                                                  Figure:Chemical Synapses