Cephalometric Investigation of First Cervical Vertebrae Morphology and Hyoid Position in Young Adults with Different Sagittal Skeletal Patterns

Table 3

Description of linear measurements.

Landmark	Definition
Hy-NSL	Linear distance from H along a perpendicular to NSL
Hy-NL	Linear distance from H along a perpendicular to the NL
Hy-Hy′/ML	Linear distance from hyoid line to mandibular line
Hy-CVT	Linear distance from H along a perpendicular to CVT
Hy-Pog	The linear distance between H and pogonion
Hy-Me	The linear distance between H and menton
𝑋	Distance between inferior border of the occipital bone and dorsal arch of first cervical vertebrae
𝑌	Distance between most superior and inferior points of first cervical vertebrae’s dorsal arch
𝑍	Distance between most inferior point of first cervical vertebrae’s dorsal arch and most superior point of second cervical vertebrae’s (axis) spinal process
Lum	Distance between anterior border of the first cervical vertebrae’s dorsal arch and posterior border of the second cervical vertebrae’s odontoid process
a-p	Distance between first cervical vertebrae’s most frontal point of tuberculum anterior and most posterior point of dorsal arch