Thirty-six tibiae from 11 female and 7 male cadavers were dissected. Anatomical and histological examinations of the plantar flexor muscle origins at the posteromedial border of the tibia were performed. Many individual variations in the type and size of muscle origin were observed. Muscle fibers and/or connective tissue in different proportions attached the muscle to the periosteum or directly to the cortical bone. The length of the attachments varied greatly and there was a considerable overlap of the muscles in some individuals. The attachments of the flexor digitorum longus overlapped the tibialis posterior and the flexor digitorum longus muscle was overlapped by the soleus muscle. In two cases the soleus muscle did not attach to the tibia at all. Our findings may shed some light on the question as to why some athletes sustain posteromedial tibial stress fractures and others develop shin splits or other posteromedial injuries from similar precipitating activity.