Mandibular neuralgia due to anatomical variations.

In our large collection of macerated human adult skulls and disarticulated skulls of young individuals we found cases with an extremely large lateral lamina of the pterygoid process. The medial wall of the infratemporal fossa was defined as its formation by the lateral lamina of the pterygoid process and the medial pterygoid muscle. The muscular part formed two-thirds and the lateral lamina one-third of this wall. In cases of a very large lateral lamina in our specimens nearly the whole medial wall was osseous. The third portion of the trigeminal nerve gives off the lingual nerve and alveolar mandibular nerve in the region of the infratemporal fossa. These two nerves generally passed between the lateral and medial pterygoid muscles to their terminal sites. In cases of extremely large lateral laminae the nerves had to make a curve in their course, following the shape of the enlarged lamina. During contraction of the pterygoid muscles both nerves can be compressed. Since the lingual nerve runs between muscular elements, tension and compression is probably avoided. In contrast, the mandibular nerve fixed between the oval and mandibular foramina cannot avoid tension and compression. The result is possible pain, especially during chewing, and may finally create a trigeminal neuralgia. Similar symptoms could be provoked by a foramen pterygospinale or ovalis canal replacing the foramen ovale.