Accessory oval foramen.

We describe an opening with smooth walls in front and medial to foramen ovale which leads to an oblique canal directed towards the fossa pterygoidea. The canal was up to 2.3 mm long and opened near the root of the pterygoid process. We called this opening "foramen ovale accessorium", and found it in 48 of 124 anatomical specimens. The foramen was present in newborns and in those aged over 80 years old on one side but rarely on both sides of the sphenoid bone. Only in a single specimen were there two foramina side by side in front of the foramen ovale. In another case, the foramen ovale accessorium was present in the anterior wall of the canalis ovalis and pointed to the fossa pterygoidea. The localization and direction of the foramen ovale accessorium led us to the conclusion that it housed some of the separate rootlets for the chewing muscles, in this case for mm pterygoidei, mm tensor veli palatini and tensor tympani. The existence and contents of the foramen ovale accessorium is important in surgical interventions on the trigeminal nerve and/or ganglion Gasseri.