Objective: To study the spatial relationships of mandibular condyle and carotid canal, jugular fossa, foramen ovale, foramen spinosum when mandible in normal physical position.
Methods: 100 native adults were examined by spiral volumatric CT. The data were transferred to workstation, three-dimensional(3d) cranial base images were reconstructed, 3D measurements were performed by using specific 3d CT landmarks. 12 points were defined and 28 distances and angles were measured in the skull base from submandibular viewpoint. The internal pole of condyle and the condylar long axis were regarded as the center point and 0 degree axis in the reference frame.
Results: Submandibular approach provided a clear vision of the internal pole of condyle and condylar long axis. The ECC was located at 12.01 +/- 2.71 mm, 5.14 +/- 1.22 degrees, Jug was located at 15.11 +/- 2.72 mm, -56.27 +/- 14.05 degrees according to the reference frame.
Conclusions: Quantitative measurements of 3D skull base can be very precise. Mandibular approach is easy to show the mandibular condyle. The reference frame is helpful to located other important structures of skull base in operation.