Evaluation of Muscle Spindle Density and Distribution of Certain Mimic Muscles: A Cadaveric Study

Abstract Background Muscle spindles (MS) are mechanoreceptors in skeletal muscle tissues that play a crucial role in proprioception and muscle tension regulation. This study aimed to evaluate the density and distribution of MS within cadaver mimic muscles. Method Muscle tissues from the buccinator, zygomaticus major, orbicularis oris, and orbicularis oculi were extracted from 16 human cadavers. The samples were subjected to histological staining with hematoxylin–eosin and Masson’s trichrome for a detailed histomorphological assessment of MS. Statistical analyses were performed using paired samples t-tests and Chi-square tests to compare the density and distribution of MS between the left and right sides of the same muscle groups. Results There was a significant correlation between muscle mass and MS density. The buccinator muscle exhibited the highest density of MS, while the orbicularis oculi muscle demonstrated the lowest density. Notably, despite similar muscle masses, the orbicularis oris muscle had a higher density of MS compared to the orbicularis oculi muscle. Conclusions This study provides evidence of variability in MS density among different mimic muscles, with significant differences observed between muscle types. The findings suggest a potential relationship between muscle function and MS density, which warrants further investigation into the role of MS in muscle function and its implications for movement disorders.