Mid Ramal Point (MRP) an Anatomical Landmark to Mandibular Foramen on Lateral Ramal Surface

Abstract

Mandible is the only movable bone in the facial skeleton. Mandibular abnormalities, its fractures are more common. In majority of cases they occur in the ramus of the mandible. The medial surface presents the mandibular foramen which contains neurovascular bundle leads into an inferior alveolar canal in the body of the mandible. Anteromedially the foremen is overlapped by a thin boney triangular lingula. The correction of mandibular deformities and treatment of ramal fractures and osteotomy procedures the mandibular ramus is approached from the external surface. So it is important to know exactly where the bone cut should made to prevent damage to neurovascular bundle, which may lead to permanent sensory loss and paralysis to muscles, mylohyoid and ant belly of digastrics. Various anatomical land marks have been proposed to guide the surgeons in locating the mandibular foremen. Caldwell and Letterman 1954 (1) made reference of a boney prominence or Antilingula present occasionally on the lateral surface of the ramus, coinciding the mandibular foremen on the medial surface. Alling (1961)(2) described a boney bulge on the lateral ramal surface coinciding mandibular foramen. Thoma (1961)(3) Described a small elevation on the surface of bone for the localization of the foremen. In present study on 50 dry mandibles done in the department of anatomy of national dental college concluded with Mid ramal point was formed by joining the four lines from the midpoint of anterior, posterior, superior, and inferior borders of the mandible. This point was marked on both surfaces of the mandibular rami which was measured in relation to mandibular foramen on gross study clinically and radiographically. It is also suggested that for oral surgeries during ramal osteotomies mid ramal point can be located by joining the 1) inferior point on the sigmoid notch and 2) anterior border of ramus just behind the third molar tooth (Midpoint of anterior border) with the 3) Midpoint of posterior border of the mandible. In the present study it was found that 76 out 100 mandibles Mid ramal point (MRP) coincided with the mandibular foremen where as in 24 rami (MRP) was found to be variable.