Figure 2. Cross-sectional areas of skeletal sites and muscles, volumes of muscles and angular variables on the MSP. (A) Zygomatic arch cross-sectional area (ZgCA), cross-sectional area of the zygomatic arch intersected by the plane through the zg_p point, which is parallel to the FP; mandibular ramus cross-sectional area (MnCA), cross-sectional area of the mandibular ramus intersected by the plane through the mnc point, which is perpendicular to the line through the mnn and the mnc; (B) Temporal muscle cross-sectional area (TCA), cross-sectional area of the temporal muscle intersected by the plane which is parallel to the FHP and 1 cm superior to the zg_e (Weijs and Hillen, 1984); masseter muscle cross-sectional area (MsCA), cross-sectional area of the masseter muscle intersected by the plane through the midpoint between the zg_a and the mn_a, which is perpendicular to the line through the zg_a and the mn_a; temporal muscle volume (TV), volume of the temporal muscle inferior to the plane which is parallel to the FHP and 1 cm superior to the zg_e; and masseter muscle volume (MsV), volume of the masseter muscle. (C) Gonial angle (GnA), angle between mn_a-gn and gn-mn_p; masseter anterior orientation angle (MsA), angle between mn_a-zg_a and the FHP; masseter zygomatic angle (MsZgA), angle between zg_p-zg_a and zg_a-mn_a; masseter antegonial angle (MsAgA), angle between zg_a-mn_a and mn_a-gn; (D) Zygomatic angle (ZgA), angle between po_l-zg_a and the FHP; and antegonial angle (AgA), angle between cd-mn_a and the FHP.

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