15 - Anatomical Variations of the Styloid Process and Associated Structures

Poster Board Number: 15
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Abstract Body : The styloid process protrudes from the inferior, petrous part of the temporal bone and serves as an attachment point for the stylohyoid, stylopharyngeus, and styloglossus muscles, as well as the stylohyoid and stylomandibular ligaments. These structures attaching to the styloid process have a complex arrangement and thus it is often a difficult region to conceptualize in three-dimensions. Currently, no systematic, thorough, investigation of the styloid process anatomy has been described. In addition, previous literature has yet to show the specific relationships of the muscles and ligaments that attach to it nor any statistical relevance or correlation between factors. This cadaveric study was designed to analyze the relationships between the origin and insertion points of the three muscles attaching to the styloid process, the presence and attachment sites of the ligaments, any ligamentous calcification, the length of the styloid process, and any respective variation across sex, age, and side of the cadaver. Dissection of these structures was performed bilaterally in 37 cadavers; each cadaver was treated as a cluster variable to account for each cadaver having two styloid processes. Results from this study have shown that the sex (M/F) of the cadaver plays a statistically significant role in the corresponding length of the styloid process (p=0.047), but side (L/R) does not (p=0.205) and that there is no correlation between sex and side with respect to length (p=0.743). The most common variation in the terms used to describe the origins of the muscles and ligaments were analyzed and calculated into a percentage and are as follows: stylohyoid m. (100% posterior, 91.5% proximal), stylopharyngeus m. (98.7% medial, 78.4% proximal), styloglossus m. (98.65% anterior), stylohyoid lig. (81.9% styloid process apex), stylomandibular lig. (81.7% lateral). This preliminary data shows educational significance in clarifying the location of these structures for students dissecting in this region as it highlights the complexity and variation of their origins, insertions, and functions. Additionally, this study provides medical professionals a more precise examination of expected variations that may be valuable across various clinical professions in their diagnosis and treatment of an elongated styloid process, or in surgical manipulation of other nearby structures. (IRB protocol number: 20220755NHR).