Fig. 7.

Sarcomere length operating ranges of masseter and temporalis muscle regions in Callithrix jacchus (blue) and Saguinus oedipus (yellow) from occlusion to our maximum gape estimate (55 deg.). Sarcomere operating ranges are superimposed on a sarcomere length—relative tension curve. The sarcomere length operating ranges of the anterior superficial masseter as well as anterior and middle temporalis in S. oedipus are significantly greater compared with C. jacchus as a function of longer moment arms (i.e. greater excursion) and shorter fibers.