Anatomical and histological notes on the origin of the long accessory styliform cartilage of the Russian flying squirrel, Pteromys volans orii

Abstract

An anatomical and histological study was made of the long accessory styliform cartilage, which supports the flying membrane of the Russian (Siberian) flying squirrel, Pteromys volans orii. The present study clarified that the flexor carpi ulnaris muscle attaches to the proximal end of the styliform cartilage, suggesting that the styliform cartilage is essentially homologous to the pisiform bone of other mammals. In addition, histological examination of specimens grouped in four age classes (one-, three-, five-, and eight-year-old) demonstrated that the styliform cartilage of P. v. orii ossifies gradually as ageing proceeds.