Update: Foramen ovale

Oval opening in the greater wing of sphenoid bone transmitting the mandibular nerve as its major content. It serves as an important landmark for neurosurgeons in certain procedures as to gain access to trigeminal nerve. Therefore, its topographic position in relation to adjacent bony landmarks provides useful tool during these procedures.

Morphometric analysis was carried out on 104 foramina ovalia of 52 dry human skulls from South India. Following dimensions of foramen ovale were measured: antero-posterior length, transverse width, distance (d(1)) from tubercle of root of zygoma to the centre of the foramen (CF) and distance (d(2)) from the midline of the base of the skull to CF. Results: The mean antero-posterior length was 7.0±2.17mm on right side and 6.8±1.40mm on left side, mean transverse width was 5.0±0.42mm and 4.70±0.91mm on right and left side respectively. Mean d(1) was 32.58±1.72mm on right side and 32.75±1.76mm on left side. Mean d(2) was 25.83±1.26mm on right side and 25.08±1.31mm on left side. Conclusion: Regional variations in the morphometric measures may be useful in neurosurgical procedures like administration of anaesthesia involving the mandibular nerve 1).


Cannulation procedures, including those utilizing neuronavigational technology, are occasionally complicated by anatomical variation of the FO, sometimes resulting in miscannulation and subsequent adverse events. The FO, while commonly thought of as oval-shaped, has also been described as “almond,” “banana,” “D shape,” “pear,” and “triangular.” Because of the importance of the FO in neurosurgical procedures and the misunderstanding of FO shape, the aim of a study is to objectively describe the shape of the FO and its most likely shape variation. A total of 211 FO were evaluated by geometric morphometric analysis. A consensus shape is presented for the FO. No significant difference was found between the shapes of left- and right-sided FO. The most likely shape variation of the FO occurs as an inverse relationship between the anteromedial-posterolateral and anterolateral-posteromedial aspects of the foramen. The capacity to visualize the average FO shape and understand the most likely shape variance, as illustrated by Zdilla et al., will aid neurosurgeons in their approach to procedures requiring cannulation of the FO 2).


1) Patil J, Kumar N, K G MR, Ravindra S S, S N S, Nayak B S, Marpalli S, L S A. The foramen ovale morphometry of sphenoid bone in South Indian population. J Clin Diagn Res. 2013 Dec;7(12):2668-70. doi: 10.7860/JCDR/2013/7548.3727. Epub 2013 Dec 15. PubMed PMID: 24551606.
2) Zdilla MJ, Fijalkowski KM. The Shape of the Foramen Ovale: A Visualization Aid for Cannulation Procedures. J Craniofac Surg. 2016 Dec 23. doi: 10.1097/SCS.0000000000003325. [Epub ahead of print] PubMed PMID: 28027173.

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