Anatomy Department, Medical School, Universidad Pontificia Católica de Chile, Santiago, Chile.
Department of Morphological Sciences (Human Anatomy and Embryology Unit), Faculty of Medicine, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Scand J Med Sci Sports. 2021 Dec;31(12):2282-2290. doi: 10.1111/sms.14045. Epub 2021 Sep 12.
Hamstring muscle injuries are the most prevalent among athletes who engage in sprinting activities. Their most frequent location is where the long head of the biceps femoris joins with the semitendinosus muscle to form the conjoint hamstring tendon. Just distal to this area, an additional group of fibers of the semitendinosus originate from medial aspect of biceps femoris. The objective of this study was to analyze the morphological characteristics of this union and to discuss its potential role in hamstring tears. Anatomical dissection was performed on 35 thighs. Samples obtained from this region were sectioned and stained with Masson's trichrome for further histological evaluation. A group of fibers from the semitendinosus muscle originating from the long head of the biceps femoris were observed in all 35 specimens. This origin was located 67 ± 12 mm from the ischial tuberosity and was 32 ± 14 mm in length. This group of muscle fibers had a width of 10.9 ± 5.3 mm and a thickness in the anteroposterior axis of 3.2 ± 1.4 mm. Its pennation angle was 9.2 ± 1.5 degrees. Microscopic examination showed muscle cells from both muscles contacting interposed tendinous tissue. In conclusion, fibers of the semitendinosus muscle consistently arise from the proximal aspect of the long head of biceps femoris. The morphological characteristics of this junction have functional implications. The horizontal component of the semitendinosus vector could pull the long head of the biceps femoris medially during its shortening-lengthening cycle, rendering it an intrinsic risk factor for hamstring injuries.
腘绳肌损伤是从事短跑运动的运动员中最常见的损伤。它们最常见的位置是长头股二头肌与半腱肌结合形成联合腘绳肌腱的地方。就在这个区域的远端，半腱肌的另一组纤维起源于股二头肌的内侧。本研究的目的是分析这种联合的形态特征，并讨论其在腘绳肌撕裂中的潜在作用。对 35 条大腿进行了解剖学解剖。从该区域获得的样本被切成薄片，并用 Masson 三色法染色，以进行进一步的组织学评估。在所有 35 个标本中都观察到来自长头股二头肌的半腱肌的一组纤维。这个起源位于坐骨结节 67±12mm 处，长 32±14mm。这组肌纤维的宽度为 10.9±5.3mm，前后轴的厚度为 3.2±1.4mm。它的羽毛角为 9.2±1.5 度。显微镜检查显示来自两块肌肉的肌细胞接触插入的腱组织。总之，半腱肌的纤维始终从长头股二头肌的近端发出。这种连接的形态特征具有功能意义。半腱肌矢量的水平成分在其缩短-延长循环中可以将长头股二头肌向内拉，使其成为腘绳肌损伤的内在危险因素。
