Brief Reports
Vol. 69 No. 2 (2025)
https://doi.org/10.4081/ejh.2025.4165

Anatomical insights into the proximal aponeurosis of the long head of the biceps femoris

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Received: 25 November 2024
Accepted: 17 April 2025
Published: 13 May 2025
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hamstrings, architecture, aponeurosis

Authors

Carmela Julia Mantecón-Tagarro
https://orcid.org/0009-0002-2717-3799
Faculty of Sport Sciences, Waseda University, Saitama, Japan.
Eri Nanizawa
Department of Anatomy, Aichi Medical University, Aichi, Japan.
Munekazu Naito
https://orcid.org/0000-0003-0618-0607
Department of Anatomy, Aichi Medical University, Aichi; Human Performance Laboratory, Comprehensive Research Organization, Waseda University, Tokyo, Japan.
Shun Otsuka
https://orcid.org/0000-0003-1832-9472
Department of Anatomy, Aichi Medical University, Aichi; Human Performance Laboratory, Comprehensive Research Organization, Waseda University, Tokyo, Japan.
Huub Maas
https://orcid.org/0000-0002-2304-2735
Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, and Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Netherlands.
Yasuo Kawakami
ykawa@waseda.jp
https://orcid.org/0000-0003-0588-4039
Faculty of Sport Sciences, Waseda University, Saitama, Japan.

The biceps femoris long head (BFlh) is prone to strain injuries, but its reasons remain unclear. This study analyzed the BFlh proximal intramuscular aponeurosis in donor samples (n=4) through morphometric, microscopic, and histological methods. Cross-sections were taken every 5% of the muscle belly to differentiate connective, adipose, and muscle tissues. The aponeurosis extended from the muscle surface, becoming intramuscular from 40-70% of the muscle belly, and ended distally. Quantitative analysis revealed significant reductions of size in both the cross-sectional area (CSA) and width of the aponeurosis at 50% of muscle length, with CSA ranging from 4.9 mm² to 13.4 mm² and widths from 6.8 mm to 12.4 mm across subjects. Dense connective tissue bundles were separated by adipose or loose connective tissues. The aponeurosis shape varied along the muscle, with T- and hook-shaped configurations, and small branches were observed distally. These findings reveal the BFlh proximal aponeurosis as a complex structure, potentially influencing its injury susceptibility.

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Ethics Approval

this study protocol was approved by the Ethical Committee of Aichi Medical University

Supporting Agencies

JSPS Kakenhi , JST SPRING
Carmela Julia Mantecón-Tagarro, Faculty of Sport Sciences, Waseda University, Saitama

Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, and Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, The Netherlands

Department of Anatomy, Aichi Medical University, Aichi, Japan

Yasuo Kawakami, Faculty of Sport Sciences, Waseda University, Saitama

Department of Anatomy, Aichi Medical University, Aichi, Japan

Human Performance Laboratory, Comprehensive Research Organization, Waseda University, Tokyo, Japan

How to Cite



1.
Mantecón-Tagarro CJ, Nanizawa E, Naito M, Otsuka S, Maas H, Kawakami Y. Anatomical insights into the proximal aponeurosis of the long head of the biceps femoris. Eur J Histochem [Internet]. 2025 May 13 [cited 2026 Jun. 28];69(2). Available from: https://www.ejh.it/ejh/article/view/4165
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