title: The orderly recruitment of motor units of the masseter and temporal muscles during voluntary isometric contraction in man.
abstract: 1. The contractile properties of the motor units of the masseter and temporal muscles of human subjects were studied during voluntary isometric contractions, using a method previously employed to examine units of a small hand muscle. 2. Over the range of forces studied (0-6 kg), the units of both muscles were recruited in an orderly fashion, with a nearly linear relationship between the voluntary force at which units were recruited and their measured twitch tensions. 3. The range of contraction times (25-90 msec) was similar to that observed for the hand muscle. In some subjects it seemed that small units, recruited at low forces, exhibited shorter contraction times.
mesh_terms: D000200:Action Potentials; D006225:Hand / Q000502:physiology; D006801:Humans; D008410:Masticatory Muscles / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology; D009431:Neural Conduction