Ossified Ligament at the base of Adult Human Dry Skull in North Indian Population: Pterygospinous and Pterygoalar Bar and Foramina

Background Ossification of ligaments at base of skull is not uncommon. The pterygospinous ligament (Civinini's ligament) is formed by pterygoid fascia which runs between the posterior margin of the lateral plate of pterygoid process and angular spine of undersurface of greater wing of the sphenoid. Ossification of this ligament forms a bony bridge (Civinini's bar) that connects spine of sphenoid with inferior surface of the greater wing, to create the pterygospinous foramen (Civinini's foramen). Pterygo alar ligament (Hyrtl‐Calori's ligament) is a thin bundle of dense connective tissue extending from the root of lateral plate of the pterygoid process to infratemporal surface of the greater wing. Ossification of this ligament results in the appearance of a bony bridge, called the pterygoalar bar, which occasionally forms a pterygo alar foramen (porus crotaphitico‐buccinatorius). The purpose of this study is to calculate the incidence of ossification of these ligaments and assess morphometrically the pterygospinous and pterygo alar bar and foramina. The knowledge of variations in the anatomy of the pterygospinous bar is important for clinical procedures done by anesthetists, dentists and maxillo‐facial surgeons. Objective To study the incidence and morphometry of Pterygospinous(PS) and Pterygo alar (PA) bar and resultant accessory foramina at the base of adult human dry skulls in the North Indian population. Method We studied 94 sides of 47 adult human dry skulls of unknown sex for presence of pterygospinous and pterygo alar bar and foramen on both sides. These skulls were studied for incidence, location, degree of ossification and relation of bar with foramen ovale and foramen spinosum. All the measurements were made using digital Vernier calipers. Result 2 of 94 sides (2.12 %) showed the presence of completely ossified PS bar on both sides along with presence of PS foramen on both sides. In 1 of 94 sides we identified the presence of PA bar and foramen (1.06%). The mean length and width of the PS bar on the right side was 11.23 mm and 1.59 mm and on the left side was 9.15 mm and 2.20 mm respectively. The PS foramen were infero‐ medial to foramen ovale on both the sides of the skull and its mean horizontal and vertical diameter was calculated to be 7.12 mm and 4.06 mm respectively on the right side and 12.18 mm and 8.31 mm respectively on the left side. The PA bar had a mean length and width of 1.82 mm, 3.60 mm respectively. Position of the Foramen spinosum(FS) was lateral in respect to the PS bar on the right side while on the left side it was lying medial to it. Conclusion We conclude that the incidence of PS bar was 2.12 % amongst the 94 sides of skulls we studied and for PA was 1.06 %. A Korean study observed 1.4 % completely ossified PS ligament in 51 sides of the skulls. Completely Ossified PA ligament was 2.8 % in 24 sides of skull. In our study we observed the Position of FS in respect to PS bar has not been mentioned by many of the literatures with the same study conducted in different regions.