Figure 1. Distribution of pure and hybrid fiber types (mean ± SD) in the human jaw-closers (temporalis, masseter, pterygoids) and jaw-openers (mylohyoid, digastric, geniohyoid); SD values are a measure for inter-individual variability. Muscle samples (jaw-closers, 6 to 9 per muscle; jaw openers, 2 to 4 per muscle) were obtained from eight cadavers. Because the fiber-type distribution of the lateral pterygoid had more similarities with that of the jaw-closers than with that of the jaw-openers, this muscle was included among the group of jaw-closers. For more information, see Korfage et al.(2001). MyHC = myosin heavy-chain.