Analysis of Foramina of the Middle Cranial Fossa with Special Emphasis on Morphology and Morphometry of Foramen OvaleAn Observational Study

Abstract

Introduction: Foramen Ovale (FO) is an important aperture present in the middle cranial fossa which transmits delicate neurovascular structures, especially the mandibular nerve. Morphological and morphometrical variations of this foramen are seen in literature and this knowledge is important as it is used for cannulation in rhizotomy for trigeminal neuralgia. Aim: To analyse the foramina of the middle cranial fossa by emphasising on morphometry and morphology of FO as mandibular nerve passes through it. Materials and Methods: This observational study was conducted in the Department of Anatomy, Vydehi Institute of Medical Sciences and Research,Banglore, Karnataka,India from January 2020 to June 2020. Fifty-one fully ossified adult skulls were utilised for this observational study. Antero-Posterior (AP) diameter, transverse diameter, area, and different shapes of the FO, distance between FO and other foramina, presence of foramen of Vesalius and accessory bony structures were studied. Independent sample t-test was done to compare the mean values of all the diameters. Results: The AP and transverse diameter of FO on the right and left side was found to be almost symmetrical. AP diameter on the right and left side was found to be 6.79±1.4 mm and 6.78±1.3 mm, respectively and transverse diameter was 3.58±0.90 mm on the right and 3.45±0.99 on left side. Distance between FO and Foramen Spinosum (FS), foramen lacerum and Meckel’s cave were similar on both the sides. The distance between FO and rotundum was greater on the right side i.e., 11.09±1.9 mm than left side which showed a diameter of 10.68±1.6 mm. The different shapes of the FO observed were oval, almond, D-shaped, elongated, round, slit and irregular. Oval shape (22 skulls on the left side and 27 skulls on the right) was the most common type. Foramen of Vesalius was observed in four skulls and accessory bony structures like bony septum, plate and spurs were also seen in the current study. Conclusion: The knowledge regarding the shape and distance between the FO and various foramina might benefit the neurosurgeons and radiologists during surgical procedures.

Keywords

• mandibular nerve
• rhizotomy
• trigeminal neuralgia