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A cadaveric study of ethmoidal foramina variation and its surgical significance in Caucasians
Saif F Abed1, Pari Shams, Sunny Shen
1Division of Basic Medical Sciences, St.George's University of London, London, UK. saif_abed@yahoo.co.uk
Aims:
To describe the morphometric and geometric relationships of the medial orbital wall ethmoidal foramina and the orbital apex in a Caucasian population.
Methods:
47 orbits from 24 formalin-fixed cadavers were exenterated. Morphometric measurements were taken between anatomical landmarks located on the medial orbital wall and geometric values were calculated.
Results:
The average distances from the anterior lacrimal crest to the anterior ethmoidal foramen, posterior ethmoidal foramen and optic canal were 25.61 mm (± 2.25), 36.09 mm (± 3.86) and 43.77 mm (± 2.52), respectively. The average distances from the anterior ethmoidal foramen to the first posterior ethmoidal foramen, last posterior ethmoidal foramen and optic canal were 13.88 mm (± 3.51), 16.60 mm (± 2.19) and 21.65 mm (± 2.59), respectively. The average distances from the first and last posterior ethmoidal foramen to the optic canal were 11.63 mm (± 3.79) and 7.25 mm (± 2.59), respectively.
Conclusion:
The distance between the posterior ethmoidal foramen and optic canal is more than double the distance quoted in the surgical literature. This is due to a high incidence of ethmoidal foramina variation. Surgeons operating on the medial orbital wall of a Caucasian population must be aware of these variations as they are a source of haemorrhage and act as landmarks of proximity to the optic canal.
