Morphologic and morphometric study of the long head of the biceps femoris in male cadavers: tendon and MTJ insights for injury diagnosis

Abstract

The long head of the biceps femoris (BFlh) is among the most frequently injured components of the hamstring complex, particularly at the myotendinous junctions (MTJs). Despite its clinical relevance, the gross morphology of the BFlh-including its tendon structure and anatomic variability-remains insufficiently characterized. This study aimed to provide a detailed anatomic and morphometric analysis of the BFlh, focusing on the proximal and distal tendons and their integration with surrounding muscle fibers. Thirty-five formalin-fixed male cadavers were dissected via a posterior longitudinal approach. Tendons were subdivided into free, intermediate, and intramuscular portions. Morphometric data were collected using digital calipers and flexible measuring tape, and correlation analyses were performed using appropriate statistical methods. The total muscle length ranged from 42.0 to 50.0 cm. The tendons showed consistent segmentation, with significant correlations between tendon lengths and limb dimensions, as well as between MTJp and MTJd lengths. The thinner, more variable intramuscular segments may contribute to increased injury susceptibility. These findings support a standardized understanding of MTJ architecture and may enhance injury classification, diagnosis, and rehabilitation strategies.

Keywords: Biceps femoris muscle; Distal tendon; Myotendinous junction; Proximal attachment; Proximal tendon.