Prevalence and morphometric characteristics of the psoas minor muscle in human fetuses: an anatomical study

In the present study, we aimed to determine the prevalence and morphometric characteristics of the psoas minor (PM) muscle in human fetuses.

A total of 67 formalin-fixed fetuses of both sexes (31 male and 36 female), aged 16-28 weeks of gestation, were examined using anatomical dissection and digital image analysis (NIS Elements AR 3.0).

The presence of the PM muscle was confirmed in 29.9% of cases, with a comparable frequency in male (32.3%) and female (27.8%) fetuses. Bilateral occurrence was noted in 60% of cases in which the muscle was present. Five morphometric parameters of the PM (total length, muscle belly length and width, and tendon length and width) were measured. In the subgroup of fetuses with bilateral presentation, no significant differences were found between the right and left sides. Due to the limited number of cases with PM muscle present, no growth modeling or correlation with fetal age or sex was performed.

The findings highlight considerable anatomical variability of the PM muscle during the prenatal period and provide preliminary reference data that may support the interpretation of advanced fetal imaging and retroperitoneal surgical planning.