Gross Anatomy of Bony Orbit and Eyeball of Sloth Bear (Melursus ursinus)

Abstract

The present study was an attempt to provide basic gross anatomical information on the bony orbit and eyeball of six sloth bears to elucidate the presence of structural modifications suiting the wild conditions. Six pairs of eyeballs of
sloth bear were used for this study. The orbit of the sloth bear were oval, equidistant, incomplete osseous and markedly projecting more frontally. The frontal surface of lacrimal bone towards the orbital margin showed a bony projection. The length and width of bony orbit of sloth bear were more than canine and felines and less than bovine and equine species. The lacrimal gland located dorsolaterally to the eyeball just medial to orbital ligament. The shape of the eyeball was circular and vertical and horizontal axes were nearly identical, antero-posterior axes being slightly longer. Pupil appeared circular and choroid showed the presence of semicircular tapetum. Some variations in the gross anatomy of bony orbit and eyeball revealed that there could be structural modifications to suit the environmental conditions.