Measurements for the direct approach to the oval foramen to apply mandibular nerve blockade

The lack of certain quotable landmarks and not taking the morphometric variations into consideration for mandibular nerve blockade can cause some complications. The aim of this study was to ensure there are data for more feasible and successful lateral extraoral approach to block the mandibular nerve by proposing reliable and quotable landmarks.

The current study was carried out on 55 skulls at the anatomy departments of the Universities of Mersin and Ankara. The length of the zygomatic arch, measurements indicating the puncture point (PP), injection depth, and injection angle were revealed. The differences between sides and the relationships between the parameters were evaluated by using paired t-test and Pearson correlation test, respectively.

Of all skulls, it is observed that the injection line passed anterior to the articular surface of the temporomandibular joint. The distance between external acoustic opening and PP showed positive correlation with the distance between oval foramen and the midpoint of the zygomatic arch on the left side (r = 0.364, P = 0.001). On the right, the correlation was close to the statistically significant level (r = 0.280, P = 0.072). The distance between external acoustic opening and PP that can be adapted to the living subjects was found as 26.31 ± 1.95 mm. Injection angle to the coronal plane was measured to be 16.39 ± 2.96 degrees. The difference between sides for this parameter was not statistically significant.

The determined parameters are suggested to be convenient and quotable to help in successful direct application under three-dimensional computed tomography or computed tomography-fluoroscopy for blocking the mandibular nerve.