EXTENSOR MUSCLE By N., Sam M.S. - 2 The muscle that when it contracts extends part of the body. Compare flexor model. EXTENSOR MUSCLE: "An extensor muscle causes extension and not flexion." Related Psychology Terms Ethics and Boundary Issues LEGAL PSYCHIATRY (Forensic Psychiatry) Counselor and Client Safety TONIC LABYRINTH REFLEX MENTAL RETARDATION (CAUSES) FLEXOR MUSCLE PRENATAL DEVELOPMENT EXTENSION REFLEX RUBROSPINAL TRACT GESELL, ARNOLD LUCIUS (1880- 1961) Cite this page: N., Sam M.S., "EXTENSOR MUSCLE," in PsychologyDictionary.org, April 7, 2013, https://psychologydictionary.org/extensor-muscle/ (accessed December 1, 2021).