Upper third: Trichion to glabella
Middle third: Glabella to subnasale
Lower third: Subnasale to menton (Fig. 2A)
Horizontal fifths: Five equally divided vertical segments of the face (Fig. 2B)
Frankfort plane: Plane defined by a line from the most superior point of auditory canal to most inferior point of infraorbital rim (Fig. 2C)
Nasofrontal angle: Angle defined by glabel la-to-nasion line intersecting with nasion-to-tip line. Normal, 115 to 130 degrees (within this range, more-obtuse angle more favorable in female, and more acute angle in male patients; Fig. 2D)
Nasofacial angle: Angle defined by glabella-to-pogonion line intersecting with nasion-to-tip line. Normal, 30 to 40 degrees (Fig. 2E)
Figure 2. Surface angles, planes, and measurements.
A: Horizontal facial thirds. B: Vertical facial fifths
Figure 2, continued. C: Frankfort plane. D: Nasofrontal angle.
Figure 2, continued. E: Nasofacial angle. F: Nasomental angle.
Figure 2, continued. G: Relationship of lips to subnasale-to-pogonion line . H: Relationship of lips to nasomental line .
Figure 2, continued. I: Mentocervical angle . J: Legan’s angle of facial convexity .
Figure 2, continued. K: Nasolabial angle. L: Nasal projection: method of Goode.
Normal projection with a “3-4-5” triangle described by Crumley (see later) gives a nasofacial angle of 36 degrees.
Nasomental angle: Angle defined by nasion-to-tip line intersecting with tip-to-pogonion line. Normal, 120 to 132 degrees (Fig. 2F)
Relationship of lips
To nasomental line: Upper lip, 4 mm behind; lower lip, 2 min behind line from nasal tip to menton (Fig. 2H)
To subnasale-to-pogonion line: Upper lip, 3.5 nun anterior; lower lip, 2.2 mm anterior (Fig. 2G)
Mentocervical angle: Angle defined by glabella-to-pogonion line intersecting with menton-to-cervical point line (Fig. 2I)
Legan facial-convexity angle: Angle defined by glabella-to-subnasale line intersecting with subnasale-to-pogonion line; normal, 8 to 16 degree (Fig. 2J)
Useful in assessing chin deficiency, candidacy for chin implant, chin advancement, or other chin alteration
Nasolabial angle: Angle defined by columellar point-to-subnasale line intersecting with
subnasale-to-labrale superius line; normal, 90 to 120 degrees (within this range, more
obtuse angle more favorable in female, and more acute in male patients; Fig. 2K) Columellar show: Alar-columellar relationship as noted on profile view; 2 to 4 mm of columellar show is normal
Nasal projection: Anterior protrusion of nasal tip from face (Fig. 2L)
Goode’s method: A line is drawn through the alar crease, perpendicular to the Frankfurt plane. The length of a horizontal line drawn from the nasal tip to the alar line (alar point-to-nasal tip line) divided by the length of the nasion-to-nasal tip line. Normal, 0.55 to 0.60 (2,3)
Crumley’s method: The nose with normal projection forms a 3-4-5 triangle (i.e., alar point-to-nasal tip line (3), alar point-to-nasion line (4), nasion-to-nasal tip line (5)] (4).
Byrd’s method: Tip projection is two-thirds (0.67) the planned postoperative (or the ideal) nasal length. Ideal nasal length in this approach is two-thirds (0.67) the midfacial height (5)
POWELL AND HUMPHRIES “AESTHETIC TRIANGLE”
Nasofrontal: 115 to 130 degrees Nasofacial: 30 to 40 degrees Nasomental: 120 to 132 degrees Mentocervical: 80 to 95 degrees (3)