The functional anatomy study of the mammalian muscles is very important for understanding the mastication mechanism during eating. It is also important for their health and breeding performance. Fifteen heads of sheep (Mean ± SD age: 18 ± 4 month) and of both sexes were included in this study.
A comparative gross anatomical study and linear measurements of the two types of masticatory muscles were conducted on slaughtered sheep heads. The physiological cross- sectional area (PCSA), maximal isometric force, torque and kinetic energy were calculated. were calculated. The study showed that the sheep jaw-closing muscles were the masseter and temporal muscles whereas the digastricus was a jaw-opening muscle. The physiological cross- sectional area (PCSA) was 3.1, 2, 3.1 cm² for the masseter, temporal and the digastric muscle, respectively. The maximal isometric force for those muscles was 6.2, 4, 6.2 cm², respectively. The force of those muscles was 0.49, 0.098, 0.196 N, respectively. The torque of those muscles was 0.49, 0.098, 0.196 Nm, respectively. While the kinetic energy of the jaw-closing group was 90 Joule, that of the jaw-opening group was 30 Joule. The values of the PCSA, force, maximum isometric force, torque and kinetic energy of the jaw-closing group were higher than those of the jaw- opening. This is suggested to be due to the increased activity of the jaw-closing muscles.