Download The Origin of the Zero-Degree Meridian Used in

AESXXX10.1177/1090820X14534677Aesthetic Surgery JournalNaini
IBUTION
TR
AL CON
ON
ERN
INT ATI
534677
research-article2014
Letter to the Editor
The Origin of the Zero-Degree Meridian Used
in Facial Aesthetic Analysis
Aesthetic Surgery Journal
2014, Vol. 34(7) NP72­–NP73
© 2014 The American Society for
Aesthetic Plastic Surgery, Inc.
Reprints and permission:
http://www​.sagepub.com/
journalsPermissions.nav
DOI: 10.1177/1090820X14534677
www.aestheticsurgeryjournal.com
Farhad B. Naini, BDS, MSc, PhD, FDS.RCS(Eng.), M.Orth.RCS(Eng.),
FDS.Orth.RCS(Eng.), FHEA
The roots of clinical facial aesthetic analysis stem from the
theoretical musings of pioneering artists and sculptors,
stretching back to antiquity. The use of such analyses in
clinical practice has been modified in accordance with
changing cultural perceptions and better understanding of
age-, sex-, and ethnicity-specific anthropometric and cephalometric normative data for various craniofacial parameters. Nevertheless, the work of the great artists and
sculptors of past ages remains inherent in our ability to
accurately diagnose variations in facial appearance.
The objective of this letter is to delve into the origin of
one of the most widely used facial aesthetic analyses, the
zero-degree meridian of the facial profile, based on 2 images
recently detected within the Leonardo da Vinci archives of
the Royal Collection (Windsor Castle, England), which is
the largest Leonardo da Vinci collection in the world.
The zero-degree meridian was described and named by
the Mexican plastic surgeon Mario Gonzalez-Ulloa as a
vertical line dropped from soft tissue nasion, perpendicular
to the Frankfort horizontal plane.1,2 Gonzalez-Ulloa described
the concept initially in 1962, although he used the term
“facial plane,”1 subsequently introducing the term “true
Meridian 0° of the face” in 1968.2 The Frankfort horizontal
plane is defined clinically as a line connecting the tragion
(the notch in the superior margin of each tragus) and
orbitale (the lowest palpable point on the inferior orbital
rim). On a lateral cephalometric radiograph, the Frankfort
horizontal plane is represented by a line connecting the
skeletal cephalometric landmarks of the porion (the superior border of the external acoustic meatus) and orbitale
(the superior border of the inferior orbital rim) (Figure 1).3
The advantages of the zero-degree meridian are its ease of
use and that it has been demonstrated to be in accordance
with the idealized profiles of classical, Renaissance, and
neoclassical artistic canons.4 However, in using this analysis, it should be kept in mind that the inclination of the
Frankfort horizontal plane, as with all anatomical reference planes, is unlikely to be coincident with the true
horizontal, particularly in a patient with a dentofacial or
Figure 1. Lateral cephalometric radiograph demonstrating
the cephalometric Frankfort plane. FH, Frankfort horizontal
plane; Me′, soft tissue menton; N′, soft tissue nasion; Or,
orbitale; Po, porion; Sn, subnasale.
craniofacial deformity. As such, contemporary use of this
analysis proposes placing the patient in a natural head
Dr Naini is a Consultant Orthodontist and Honorary Senior Lecturer,
Kingston Hospital and St George’s Hospital and Medical School,
London, United Kingdom.
NainiNP73
Figure 3. Detail from Study of the Valves and Muscles of the
Heart (c. 1513), pen and brown ink on blue paper,
260 × 200 mm, Windsor Castle, Royal Library (RL 19093).
Reprinted with permission from The Royal Collection Trust/©
Her Majesty Queen Elizabeth II 2014.
Figure 2. Detail from Studies of the Proportions of the Face,
Leg and Arm (c. 1490), pen and 2 shades of brown ink over
traces of stylus, 203 × 279 mm, Windsor Castle, Royal
Library (RL 19140). Reprinted with permission from The
Royal Collection Trust/© Her Majesty Queen Elizabeth II
2014.
position, in relation to a hanging “true vertical” plumb
line, parallel to which may be drawn the zero-degree
meridian and perpendicular to which is drawn a true horizontal line, to act as the Frankfort plane.4
The author’s research in the Leonardo da Vinci archives
of the Royal Collection has uncovered 2 images, which
appear to depict the zero-degree meridian. The first image
(Figure 2) is from around 1490, which coincides with the
time that many of Leonardo’s proportional drawings are
thought to have been created, including the famous
Vitruvian Man. The detail of the facial profile demonstrated is but a small part of the whole page, upside-down
in the original, and surrounded by images of proportional
drawings of the arms and legs. It is likely to be from the
time that Leonardo was researching and forming his ideas
regarding idealized human proportions for art and sculpture. The second image (Figure 3) is thought to be from a
later date, around 1513, and is a detail of a facial profile,
which is part of a page dealing predominantly with cardiac
anatomy. Both figures, however, appear to demonstrate a
vertical facial profile line, from the nasion region, through
the subnasale and to just anterior of the soft tissue pogonion, which is the essence of the zero-degree meridian.
Researching the historical development of our understanding of the human face is imperative, permitting the
weighing and evaluation of the interrelationships between
art and clinical practice. History, when unraveled enough,
remains a great teacher, and great minds spanning the ages
appear to think alike.
Disclosures
The author declared no potential conflicts of interest with
respect to the research, authorship, and publication of this
article.
References
1.Gonzalez-Ulloa M. Quantitative principles in cosmetic
surgery of the face (profileplasty). Plast Reconstr Surg.
1962;29(2):187-198.
2.Gonzalez-Ulloa M, Stevens E. The role of chin correction in
profileplasty. Plast Reconstr Surg. 1968;41:477-486.
3.Naini FB. The Frankfort plane and head positioning in
facial aesthetic analysis: the perpetuation of a myth. JAMA
Facial Plast Surg. 2013;15(5):333-334.
4. Naini FB. Facial Aesthetics: Concepts and Clinical Diagnosis.
Oxford, England: Wiley-Blackwell; 2011.