In anatomy, a ganglion (pl. ganglia) is a tissue mass. Neurology In neurological contexts, ganglia are composed mainly of somata and dendritic structures that often interconnect with other ganglia to form a complex system of ganglia known as a plexus. Ganglia provide relay points and intermediary connections between different neurological structures in the body, such as the peripheral and central nervous systems. There are two major groups of ganglia: dorsal root ganglia (also known as the spin… (More on Ganglia)