Quantitative anatomy of the rotator cuff muscle in the human fetus based on the teres minor muscle

The teres minor muscle is one of the components of the rotator cuff. Particularly in terms of anatomical variability and prenatal development it is less thoroughly Described in current literaturę. The aim of the present study was to examine the growth dynamics of the teres minor muscle in the human fetus, based on its linear and planar parameters. Using anatomical dissection, digital image analysis (NIS Elements AR 3.0), and statistical tools (Student’s t-test, ANOVA, regression analysis), morphometric parameters of the teres minor muscle were measured in 36 human fetuses of both sexes (17♂, 19♀), aged 18–30 weeks of gestation. The teres minor muscle showed no significant sex- or side-related differences. Muscle length increased logarithmically with gestational age, while width, circumference, and projection surface area followed linear growth patterns. The normative values obtained for the teres minor muscle may serve as a developmental reference for prenatal anatomical studies and have potential clinical relevance in pediatric imaging, surgery, and neonatology. • First developmental analysis of the fetal teres minor muscle. • Muscle length shows logarithmic growth between 18–30 weeks GA. • Width, circumference, and area increase linearly with fetal age. • No sex- or side-related differences in muscle development. • Normative data support prenatal imaging and pediatric surgery.