Surgical anatomy of the infratemporal fossa using the transmaxillary approach

In this study we evaluated the ability of the transmaxillary route to expose the elements of the infratemporal fossa (ITF). Five adult cadaver heads were dissected on both sides, after making a paralateronasal incision. The maxillary branch of the trigeminal nerve served as a superior landmark to progress into the retroantral space and pterygopalatine fossa. The maxillary artery, lateral pterygoid muscle, pterygoid venous plexus, foramen rotundum and foramen ovale were identified. Distances between those elements and angle of approaches of the foramen ovale and foramen rotundum were measured in the horizontal plane. In all cases, the anterior loop of the maxillary artery and the sphenopalatine artery were located in the proximal retroantral fatty space and could be ligated without optic magnification. The maxillary nerve could be followed up to the foramen rotundum at a 44 mm mean distance from the opening. The mean angle of vision to the foramen rotundum was 31 degrees. Under the greater sphenoid wing and lateral to the pterygoid process, desinsertion and partial resection of the lateral pterygoid muscle were required to identify the pterygoid venous plexus and foramen ovale. The pterygoid venous plexus was organized as a compact network of channels between and superior to the muscle fibers; it was in close relation with the foramen ovale. Access to the foramen ovale was deep (mean 56 mm) and narrow (20 degrees). Our results indicate that the transmaxillary approach is a minimally invasive procedure that gives an appropriate window to the structures of the retroantral space and to the pterygomaxillary fissure and pterygopalatine fossa. Monitoring of the retropterygoid portion of the infratemporal fossa by this route is inadequate.