Plexus ( plx ; Galen, c192 ) : A general term for a group of interconnecting neurons (Waldeyer, 1891) or nerve (Herophilus, c335-280 BC) components that may be a sheet of interwoven fibers or a course mesh of communicating nerves, without or with neuron cell bodies (Deiters, 1865), including ganglia (Galen, c173); see Oxford English Dictionary, 1989; Bullock & Horridge, 1965, p. 1606). Examples include nerve nets, prevertebral plexuses, and spinal nerve plexuses (with postplexus spinal nerves distal to them). Galen (c192; see translation by Duckworth, 1962, p. 243) used the term plexus in describing the macrodissected adult mammalian brachial plexus (Camper, 1760).