(A–E) Distribution of ridges around the body circumference. (A) According to the sagittal axis, ridges are named left ridges and right ridges. (B) According to the frontal axis, ridges are named dorsal ridges and ventral ridges. (C) Division into quadrants resulting from the intersection of sagittal and frontal axes. Ridges are named left-dorsal, right-dorsal, right-ventral, and left-ventral ridges. (D) Division into quadrants resulting from the intersection of the axes “right-ventral/left-dorsal” and “left-ventral/right-dorsal”. Ridges are named mid-dorsal, mid-right, mid-ventral, and mid-left ridges. (E) Division into octants. Ridges are named dorsal-right-dorsal, right-right-dorsal, right-right-ventral, ventral-right-ventral, ventral-left-ventral, left-left-ventral, left-left-dorsal, and dorsal-left-dorsal ridges. Abbreviations: D: dorsal side; FA: frontal axis; L: left side; LV/RD: left-ventral/right-dorsal axis; R: right side; RV/LD: right-ventral/left-dorsal axis; SA: sagittal axis; V: ventral side; dr: dorsal ridges; d-l-dr: dorsal-left-dorsal ridges; d-r-dr: dorsal-right-dorsal ridges; lr: left ridges; l-dr: left-dorsal ridges; l-vr: left-ventral ridges; l-l-dr: left-left-dorsal ridges; l-l-vr: left-left-ventral ridges; m-dr: mid-dorsal ridges; m-lr: mid-left ridges, m-rr: mid-right ridges, m-vr: mid-ventral ridges; r-dr: right-dorsal ridges; rr: right ridges; r-vr: right-ventral ridges; r-r-dr: right-right-dorsal ridges; r-r-vr: right-right-ventral ridges; vr: ventral ridges, v-l-vr: ventral-left-ventral ridges; v-r-vr: ventral-right-ventral ridges.