Characterizing the Lateral Border of the Frontalis for Safe and Effective Injection of Botulinum Toxin.
BACKGROUND
The forehead is a common site for injection of botulinum neurotoxin type A (BoNT-A) to treat hyperactive facial muscles. Unexpected side effects of BoNT-A injection may occur because the anatomy of the forehead musculature is not fully characterized.


OBJECTIVE
The authors described the lateral border of the frontalis in terms of facial landmarks and reference lines to determine the safest and most effective forehead injection sites for BoNT-A.


METHODS
The hemifaces of 49 embalmed adult Korean cadavers were dissected in a morphometric analysis of the frontalis. L2 was defined in terms of FT (the most protruding point of the frontotemporal region), L0 (the line connecting the infraorbital margin with the tragus), and L1 (the line parallel to L0 and passing through FT) such that L2 was positioned 45° from L1 and passed through FT.


RESULTS
The distance from FT to the superior margin of the orbicularis oculi was 12.3 ± 3.3 mm. The frontalis extended more than 5 cm along L2 in 49 of 49 cases (100%), more than 6 cm in 47 cases (95.9%), more than 7 cm in 34 cases (69.4%), more than 8 cm in 11 cases (22.4%), and more than 9 cm in 3 cases (6.1%). The lateral border of the frontalis ran parallel to and within 1 cm of the medial side of L2.


CONCLUSIONS
Surface anatomy mapping can assist with predicting the lateral border of the frontalis to minimize the side effects and maximize the efficiency of BoNT-A injections into the forehead.
Mr Choi is a Graduate Student, Dr Hu is an Associate Professor, and Dr H-J Kim is a Professor, Division of Anatomy and Developmental Biology, Department of Oral Biology, Human Identification Research Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Dr Won is an Assistant Professor, Department of Occupational Therapy, Semyung University, Jecheon, Republic of Korea. Dr Lee is an Assistant Professor, Department of Dental Hygiene, School of Health and Medicine, Namseoul University, Choenan, Republic of Korea. Dr S-T Kim is a Professor, Department of Oral Medicine, TMJ and Orofacial Pain Clinic, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Dr Tansatit is a Professor, Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
You-Jin
YJ
Choi
Mr Choi is a Graduate Student, Dr Hu is an Associate Professor, and Dr H-J Kim is a Professor, Division of Anatomy and Developmental Biology, Department of Oral Biology, Human Identification Research Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Dr Won is an Assistant Professor, Department of Occupational Therapy, Semyung University, Jecheon, Republic of Korea. Dr Lee is an Assistant Professor, Department of Dental Hygiene, School of Health and Medicine, Namseoul University, Choenan, Republic of Korea. Dr S-T Kim is a Professor, Department of Oral Medicine, TMJ and Orofacial Pain Clinic, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Dr Tansatit is a Professor, Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Sung-Yoon
SY
Won
Mr Choi is a Graduate Student, Dr Hu is an Associate Professor, and Dr H-J Kim is a Professor, Division of Anatomy and Developmental Biology, Department of Oral Biology, Human Identification Research Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Dr Won is an Assistant Professor, Department of Occupational Therapy, Semyung University, Jecheon, Republic of Korea. Dr Lee is an Assistant Professor, Department of Dental Hygiene, School of Health and Medicine, Namseoul University, Choenan, Republic of Korea. Dr S-T Kim is a Professor, Department of Oral Medicine, TMJ and Orofacial Pain Clinic, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Dr Tansatit is a Professor, Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Jae-Gi
JG
Lee
Mr Choi is a Graduate Student, Dr Hu is an Associate Professor, and Dr H-J Kim is a Professor, Division of Anatomy and Developmental Biology, Department of Oral Biology, Human Identification Research Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Dr Won is an Assistant Professor, Department of Occupational Therapy, Semyung University, Jecheon, Republic of Korea. Dr Lee is an Assistant Professor, Department of Dental Hygiene, School of Health and Medicine, Namseoul University, Choenan, Republic of Korea. Dr S-T Kim is a Professor, Department of Oral Medicine, TMJ and Orofacial Pain Clinic, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Dr Tansatit is a Professor, Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Kyung-Seok
KS
Hu
Mr Choi is a Graduate Student, Dr Hu is an Associate Professor, and Dr H-J Kim is a Professor, Division of Anatomy and Developmental Biology, Department of Oral Biology, Human Identification Research Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Dr Won is an Assistant Professor, Department of Occupational Therapy, Semyung University, Jecheon, Republic of Korea. Dr Lee is an Assistant Professor, Department of Dental Hygiene, School of Health and Medicine, Namseoul University, Choenan, Republic of Korea. Dr S-T Kim is a Professor, Department of Oral Medicine, TMJ and Orofacial Pain Clinic, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Dr Tansatit is a Professor, Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Sung-Taek
ST
Kim
Mr Choi is a Graduate Student, Dr Hu is an Associate Professor, and Dr H-J Kim is a Professor, Division of Anatomy and Developmental Biology, Department of Oral Biology, Human Identification Research Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Dr Won is an Assistant Professor, Department of Occupational Therapy, Semyung University, Jecheon, Republic of Korea. Dr Lee is an Assistant Professor, Department of Dental Hygiene, School of Health and Medicine, Namseoul University, Choenan, Republic of Korea. Dr S-T Kim is a Professor, Department of Oral Medicine, TMJ and Orofacial Pain Clinic, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Dr Tansatit is a Professor, Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Tanvaa
T
Tansatit
Mr Choi is a Graduate Student, Dr Hu is an Associate Professor, and Dr H-J Kim is a Professor, Division of Anatomy and Developmental Biology, Department of Oral Biology, Human Identification Research Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Dr Won is an Assistant Professor, Department of Occupational Therapy, Semyung University, Jecheon, Republic of Korea. Dr Lee is an Assistant Professor, Department of Dental Hygiene, School of Health and Medicine, Namseoul University, Choenan, Republic of Korea. Dr S-T Kim is a Professor, Department of Oral Medicine, TMJ and Orofacial Pain Clinic, College of Dentistry, Yonsei University, Seoul, Republic of Korea. Dr Tansatit is a Professor, Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Hee-Jin
HJ
Kim
D065087:Acetylcholine Release Inhibitors / Q000008:administration & dosage*; D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D002102:Cadaver; D003357:Cosmetic Techniques; D005152:Facial Muscles / Q000033:anatomy & histology*; D005260:Female; D005546:Forehead / Q000033:anatomy & histology*; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D012060:Rejuvenation; D056910:Republic of Korea
D065087:Acetylcholine Release Inhibitors; D019274:Botulinum Toxins, Type A; C545476:incobotulinumtoxinA