Nerve supply of the proximal sesamoid bone in the horse

In chronical proximal sesamoid bone lameness it is difficult to localise the exact site of pain. A specific diagnostic analgesia is not available because of a deficiency of detailed information about the nerve supply to the proximal sesamoid bones and surrounding area. A macroscopic study of the nerve distribution to the proximal sesamoid bones of 10 foals and 5 adult horses revealed that these bones are innervated by two branches, in this study called the medial and lateral sesamoidean nerve, respectively, originating from the medial and lateral palmar nerve. Histology of the left forelimbs of two fetuses and one foal confirmed the macroscopic findings. Additionally, histology of ten proximal sesamoid bones of adult horses showed that myelinated nerve fibres are present in the nutrient foramina and in the trabecular bone, accompanying the larger arteries. This study provides possibilities for future diagnostics of proximal sesamoid bone lameness by specific local perineural analgesia.