Positional Relationship between the Pectoralis
Major and External Abdominal Oblique Muscles
for Consideration during Dual-Plane Breast
HEE-JIN KIM ,
Division in Anatomy and Developmental Biology, Department of Oral Biology, Human Identiﬁcation Research
Institution, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea
Change Clinic, Apgujung-ro, Gangnam-gu, Seoul, 06010, South Korea
ES Clinic, Sinchon-ro, Seodaemun-gu, Seoul, 03787, South Korea
Miaero Clinic, Gwanak-ro, Gwanak-gu, Seoul, 08788, South Korea
During dual plane breast augmentation (DPBA), the costal origin of the pector-
alis major (the PM) should be cut to ensure appropriate coverage and position-
ing of an implant. However, surgeons sometimes make inappropriate planar
incisions and insufﬁcient muscular incisions because the external abdominal
oblique (the EAO) muscle partially overlaps the lateral portion of the PM. The
goal of this study was to clarify the positional relationship between the PM and
EAO with the aim of improving the accuracy of implant and muscular incisions
during DPBA. Forty sides of 20 embalmed and fresh cadavers were dissected.
The midline and midclavicular line (MCL) were used as reference lines for
measurements. We clariﬁed the overlapping patterns between the PM and
EAO, and measured the distances from the MCL to the borders of those two
muscles. The costal part of the PM originated from the 5th (25%), 6th (70%),
or 7th rib (5%), respectively. The distances from the MCL to the lateral border
of the PM at the 4th, 5th, and 6th ribs were 49.8 mm, 30.5 mm, and 6.3 mm,
respectively. In 90% of the specimens, the PM and the EAO overlapped near
the MCL. The width of the overlapping portion between the PM and EAO was
about 25 mm. This study is one of the ﬁrst to suggest an innovative approach
for explaining the positional relationships between the PM and EAO. Our ﬁnd-
ings can be useful for surgeons attempting to produce optimal outcomes in
DPBA, especially in procedures that involve patients of different races. Clin.
Anat. 31:339–346, 2018.
2018 Wiley Periodicals, Inc.
Key words: mammaplasty; pectoralis major; external abdominal oblique
*Correspondence to: Hee-Jin Kim, Room 601, Department of Oral Biology, Yonsei University College of Dentistry, 50 Yonseiro,
Seodaemun-gu, Seoul 03722, South Korea. E-mail: firstname.lastname@example.org AND Hyoung-Moon Kim, Miaero Clinic, Daewoo Dio Superium
1-B305, 164, Gwanak-ro, Gwanak-gu, Seoul, Korea. E-mail: email@example.com
Financial Disclosure Statement: The authors have no commercial associations or ﬁnancial disclosures that might pose or create a
conﬂict of interest with the information presented in this article.
Received 1 November 2017; Revised 26 January 2018; Accepted 5 February 2018
Published online 20 February 2018 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/ca.23059
2018 Wiley Periodicals, Inc.
Clinical Anatomy 31:339–346 (2018)