spasticity /spastis′itē/ [Gk, spastikos, drawing in] , a form of muscular hypertonicity with increased resistance to stretch. It usually involves the flexors of the arms and the extensors of the legs. The hypertonicity is often associated with weakness, increased deep reflexes, and diminished superficial reflexes. Moderate spasticity is characterized by movements that require great effort and lack of normal coordination. Slight spasticity may be marked by gross movements that are coordinated smoothly but combine selective movement patterns that are uncoordinated or impossible.