Study of Pterygospinous and Pterygoalar Bars in Relation to Foramen Ovale in Dry Human Skulls

Abstract

Abstract Background Anatomical knowledge of bony bridges around the foramen ovale may be helpful for diagnostic and invasive neurosurgical procedures like electroencephalogram analysis, trigeminal rhizotomy, biopsy of cavernous sinus tumors, and mandibular nerve block.Lateral pterygoid plate forms an important landmark for mandibular anesthesia; therefore, any variation related to lateral pterygoid plate is likely to create confusion during the maneuver of anesthesia. Aims and Objective The aim of the study was to explore any bony obstacle within and around Foramen ovale. Obstacles in form of ossified complete or incomplete ligaments. Additional foramina formed by ligaments or any bony enlargement might disturb the structures passing through the Foramen ovale. Methods Around 530 dried crania (from medical colleges in Uttarakhand and Uttar Pradesh) were observed to find ossified ligaments and foramen formed by them. Crania associated with bilateral enlarged lateral pterygoid plate other than the average width of 1.5 cm were included in this study. Length of ligaments and width of pterygoid plate were measured by digital Vernier calipers. Results Out of 530 crania, unilateral 52 ossified pterygospinous ligament (incomplete 31 and complete 21) were observed. Among them some rare variation was found along with ossified pterygospinous and pterygoalar ligament, one cranium along with unilateral pterygospinous bar was also having bar within foramen ovale, forming an accessory osseous compartment, found to be rare kind of variation. Another unilateral complete pterygospinous bar was enclosing two foramens instead of one. Only single cranium was found to have pterygoalar bar, related medial to foramen ovale. One cranium was associated with bilateral enlarged lateral pterygoid plate (i.e., 2.5 cm) was also found to be obliterating the space, that is, retropharyngeal and parapharyngeal space for surgeons. Conclusion This study would provide the anatomical knowledge of these bony bridges around the foramen ovale and may be helpful for diagnostic and neurosurgical procedure like microvascular decompression by percutaneous trigeminal rhizotomy for trigeminal neuralgia, percuatneous biopsy of cavernous sinus tumor and mandibular nerve block by lateral subzygomatic route. Thus, lateral pterygoid plate forms an important landmark for mandibular anesthesia.