Morphological Measurements of Innominate Foramina and Bony Spurs along the Base of Sphenoid as a Potential Risk Factor for Neurovascular Entrapment, Radiological Interpretation and Surgical Access

Abstract

Background: Restricted access and compression of neurovascular structures at various anatomic variations at the skull base poses a challenge to surgeons, neurologists and anesthetists. The present study was performed with the objective of providing morphometric analysis of innominate foramina, and anomalous bony bars and spurs along the infratemporal surface of the greater wing of the sphenoid and reviewing the practical significance of dealing with this region. Methods: A total of 100 dry-aged human adult skulls from the archives of the osteology library of the Department of Anatomy were studied. A detailed morphometric analysis of such innominate foramina and anomalous osseous structures along the base of the sphenoid was performed using a sliding digital vernier caliper. Results: Anomalous bony bar was found in 22 skulls (25.28%). A complete bar was observed at eight (9.1%). An innominate foramen was located inferomedial to foramen ovale (5 unilateral and 3 bilateral) with a mean anteroposterior diameter of 3.44 mm and a mean transverse diameter of 3.16 mm. Conclusion: Neurovascular structures may be compressed by abnormal bony outgrowths or while traversing through such unnamed bony foramina. The latter may also be overlooked and mistaken during radiological interpretation leading to delayed diagnosis. Such unnamed foramina and bony outgrowths need to be documented in the literature due to their surgical, and radiological implications and limited citations.