Morphometric Study of the Intraorbital Muscles (Musculi bulbi) in Chinchilla (Chinchilla lanigera)

Year 2025, Volume: 10 Issue: 1, 453 - 457, 30.04.2025

Ömer Gürkan Dilek , Emine Karakurum

https://doi.org/10.24880/meditvetj.1603876

Abstract

The intraorbital muscles (musculi bulbi) are critical for the movement and stabilization of the eyeball, enabling essential ocular functions such as rotation, convergence, and visual tracking. While much is known about the ocular musculature of larger mammals, little research has been conducted on the musculi bulbi in small rodents, particularly the chinchilla (Chinchilla lanigera), a species with specialized nocturnal adaptations. This study presents a detailed morphometric analysis of the intraorbital muscles in adult chinchillas, examining the size, shape, and structural variations of these muscles. Using dissection and digital caliper measurements, we analyzed 12 chinchillas (6 males and 6 females), focusing on muscle length, thickness, width, and attachment points. Key findings include the identification of an L-shaped curve in the m. obliquus dorsalis and a tendinous termination at its end, as well as the observation that the m. obliquus dorsalis is the longest muscle in females. These results highlight both common and unique features of ocular muscle structure, such as the straight-line attachment of the rectus muscles and the oblique alignment of the m. obliquus ventralis. The study also reveals potential sex-based differences in ocular muscle morphology, which may have implications for eye movement and visual acuity. This work contributes to the understanding of the functional adaptations of ocular musculature in rodents, offering a comparative basis for further studies on the evolution and biomechanics of eye movement in mammals.

Keywords

Intraorbital muscles , Chinchilla lanigera , Ocular musculature , Morphometric analysis , Visual adaptations.

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