Yeo In-Seung, Kim Miri, Lee Hyung-Jin
Department of Anatomy, College of Medicine, The Soonchunhyang University of Korea, Soonchunhyang 6-Gil, Dongnam-Gu, Cheonan-Si, Chungcheongnam-Do, 31151, Republic of Korea.
Translational Research Unit for Anatomy and Analgesia, Seoul, Republic of Korea.
Surg Radiol Anat. 2024 Dec 6;47(1):21. doi: 10.1007/s00276-024-03523-6.
The tibialis posterior (TP), flexor digitorum longus (FDL), and flexor hallucis longus (FHL) are muscles that contribute to the stability of foot and ankle movements, playing a crucial role in achieving optimal gait. However, a comprehensive examination of the anatomical characteristics and histological variances of each muscle has not been conclusively established.
A total of 10 un-embalmed cadavers were dissected, and muscles from each cadaver were consistently harvested from the musculotendon junction. The ratio of collagen and elastic fibers was assessed through three immunohistological analyses, focusing on distinct histological characteristics in type I (slow twitch) and type II (fast twitch) fibers. Additionally, Ultrasonography was utilized to compare and analyze the thickness, fascicle angle, and muscle fiber length of each muscle.
Concerning the relative proportion of elastic fibers to collagen, the TP exhibited the highest collagen content (21.9 ± 0.30%, mean ± standard deviation), while the FHL had the highest elastic fiber proportion (48.4 ± 0.44%). The TP predominantly comprised slow type muscle fibers (36.88 ± 0.83%), whereas the FHL contained a higher density of fast type muscle fibers (32.46 ± 4.02%). US analysis indicated that the thickness of the TP was relatively greater (2.0 ± 0.2 mm) compared to the FDL (1.2 ± 0.1 mm) and FHL (1.1 ± 0.1 mm). Additionally, the fascicle length was notably longer in the TP (25.6 ± 4.1 mm).
Our anatomical and histological findings indicate that the tibialis posterior (TP) is the thickest with a significant physiological angle and a high collagen content. This characteristic enables the TP to provide stability by transmitting a constant force to the calf. On the other hand, the flexor hallucis longus (FHL) exhibits the highest elastic fiber content, confirming its ability to exert instantaneous, swift, and powerful force.
胫后肌（TP）、趾长屈肌（FDL）和拇长屈肌（FHL）是有助于足踝关节运动稳定性的肌肉，在实现最佳步态中起关键作用。然而，尚未对每块肌肉的解剖特征和组织学差异进行全面研究。
共解剖10具未防腐尸体，从每具尸体的肌腱连接处一致地获取肌肉。通过三项免疫组织学分析评估胶原纤维和弹性纤维的比例，重点关注I型（慢肌纤维）和II型（快肌纤维）纤维的不同组织学特征。此外，利用超声检查比较和分析每块肌肉的厚度、肌束角度和肌纤维长度。
关于弹性纤维与胶原纤维的相对比例，胫后肌的胶原含量最高（21.9±0.30%，平均值±标准差），而拇长屈肌的弹性纤维比例最高（48.4±0.44%）。胫后肌主要由慢肌纤维组成（36.88±0.83%），而拇长屈肌含有更高密度的快肌纤维（32.46±4.02%）。超声分析表明，胫后肌的厚度（2.0±0.2mm）相对于趾长屈肌（1.2±0.1mm）和拇长屈肌（1.1±0.1mm）相对更厚。此外，胫后肌的肌束长度明显更长（25.6±4.1mm）。
我们的解剖学和组织学研究结果表明，胫后肌最厚，具有显著的生理角度和高胶原含量。这一特征使胫后肌能够通过向小腿传递恒定的力来提供稳定性。另一方面，拇长屈肌的弹性纤维含量最高，证实了其施加瞬时、迅速和强大力量的能力。
