Anatomical Study of Pterygospinous and Pterygoalar Bar in Human Skulls with their Phylogeny and Clinical Significance.

Abstract

Pterygospinous and pterygoalar ligaments present at the cranial base may sometimes get ossified leading to the formation of complete or incomplete bony bars in relation to foramen ovale. These are of clinical importance because these may obliterate the foramen ovale causing mandibular neuralgia. They may cause trouble in performing thermocoagulation and anaesthesia for trigeminal neuralgia. They may pose surgical difficulty in approaching the retro and parapharyngeal spaces and hence the anatomy of these bony bars is very important. The present study was conducted in 100 dry human skulls of unknown sex to know the incidence, side, degree of ossification (complete/ incomplete) and relation of the pterygospinous and pterygoalar bars to the foramen ovale. Pterygospinous and pterygoalar bars were seen in 41 skulls which were classified into Type I (26.83%), Type II (58.54%) and Type III (14.63%) based on the presence of pterygospinous bar, pterygoalar bar or both together. Pterygospinous bars were seen in 17 skulls of which, one skull (5.88%) had complete and 16 skulls (94.12%) showed incomplete bars. Out of the 30 skulls with pterygoalar bars, complete bar was seen in one (3.33%) and incomplete in 29 skulls (96.67%). These bars were seen more on the left side of the skull than on the right. They were in close relation to the foramen ovale; the pterygospinous bar was inferior or medial to foramen ovale and pterygoalar bar was lateral, inferior or medial to the foramen ovale. The presence of the pterygospinous and pterygoalar bars cause variety of symptoms due to neurovascular entrapment and also obstruct surgical approaches to the base of skull. Hence the anatomical knowledge of these osseous bars is essential for anaesthetists, radiologists, dentists and neurosurgeons to increase the success of diagnostic evaluation and surgical approaches to the cranial base.