Study of Mandibular Foramen in Adult Human Mandible Bones: An Osteological Study

Introduction: The mandibular foramen is located on the medial surface of the ramus of mandible through which inferior alveolar nerve and vessels pass and supply the lower jaw. For dentists inferior alveolar nerve block is important to anesthetize the lower jaw for conducting various surgical procedures. Aims: To determine the accurate position of mandibular foramen through which inferior alveolar nerve and vessels were passing and supply the lower jaw and its clinical importance. Methods: This study was conducted on 35 dry mandible bones consisting of 70 mandibular foramens of unknown sex. All the important parameters were studied using vernier caliper. Results: The mean distance of mandibular foramen from mandibular notch was 21.00 mm on right side and 20.29 mm on left side, from posterior border was 12.63 mm on right side and 12.37 mm on left side, from angle of mandible was 20.60 mm on right side and 20.46 mm on left side, from base of the mandible was 23.57 mm on right side and 23.6 mm on left side, from anterior border was 16.74 mm on right side and 16.89 mm on left side. Conclusion: The accurate position of mandibular foramen varies. The knowledge of the average distance of mandibular foramen from various landmarks is useful for dental anesthesia and also helps to avoid complications.

Topography of the location of mental foramen in dried edentulous human mandible and its clinical implication

The mental foramen is an oval or round opening on external surface of mandible and transmits mental nerve and vessels. Mostly located at apex of second mandibular premolar or between the apices of premolars. The study was commenced on 60 dried edentulous mandibles with the aim to determine location of mental foramen(MF) with reference to surrounding anatomical landmarks. By measuring its distance from midline (symphysis menti), posterior border of ramus of mandible, lower border of mandible. Length of lower border (Base) of mandible was also measured. In present study most common shape of mental foramen was round (70%). The mean distances of MF from midline are 24.36mm on right side and 24.15mm left side. From posterior border of ramus are 64.45mm on right side and 64.15mm on left side. From base of mandible are 12.29mm on right side and 12.48mm on left side. Length of base mandible (midline to angle of mandible) is 83.27mm right side and 83.12mm left side. Ratio of distance from symphysis menti to MF and length of base of mandible are same on both sides that are 0.29. There is statistically significant positive correlation between distance from symphysis menti to MF and length of base of mandible.The MF plays a very important role in treatment planning and its location needs to be considered prior to placement of dental-implants, regional anesthesia, osteotomy-surgeries and during complete denture-fabrication in order to avoid MN injury and related complications.

Mental foramen of Human Mandible: Morphometric Study

Aim: The aim of our study was to perform a morphometric analysis of the mental foramen in senegalese context. Material and method: The study was performed on thirty-nine dry mandibles of adult humans. On these mandibles, the number of mental foramen present and their shape were noted on inspection. The situation of the foramen in relation to the lower teeth was studied according to a methodology already described. The following measurements were made: the distance between the foramen and the other landmarks of the mandible (symphysis, basilar border, posterior border), vertical and horizontal diameters. Results: The number of mental foramina were 39 on the right and 40 on the left: one mandible presented a double foramen on the left. The oval shape was predominant. The most frequent situation was below the second premolar on both sides. The mean distance between the foramen and the mandibular symphysis was 25mm on both sides. The distance between the foramen and the basilar border of the mandible was on average 13mm on the right and 14mm on the left. The distance between the foramen and the posterior border of the mandible was on average 72mm on the right and 73mm on the left. The average vertical diameter was 33mm on the right and 32mm on the left, and the average horizontal diameter was 4mm on both sides. Conclusion: Mental foramen is a constant anatomical structure, found on all the mandibles studied. The results can be superimposed on those described in the majority of studies carried out on the mental foramen. Key words: Mental Foramen, Mandible Anatomy, Morphometry.

Role of the parietooccipital fissure and its implications in the pathophysiology of posterior medial temporal gliomas

OBJECTIVE The parietooccipital fissure is an anatomical landmark that divides the temporal, occipital, and parietal lobes. More than 40% of gliomas are located in these three lobes, and the temporal lobe is the most common location. The parietooccipital fissure is located just posterior to the medial temporal lobe, but little is known about the clinical significance of this fissure in gliomas. The authors investigated the anatomical correlations between the parietooccipital fissure and posterior medial temporal gliomas to reveal the radiological features and unique invasion patterns of these gliomas. METHODS The authors retrospectively reviewed records of all posterior medial temporal glioma patients treated at their institutions and examined the parietooccipital fissure. To clarify how the surrounding structures were invaded in each case, the authors categorized tumor invasion as being toward the parietal lobe, occipital lobe, isthmus of the cingulate gyrus, insula/basal ganglia, or splenium of the corpus callosum. DSI Studio was used to visualize the fiber tractography running through the posterior medial temporal lobe. RESULTS Twenty-four patients with posterior medial temporal gliomas were identified. All patients presented with a parietooccipital fissure as an uninterrupted straight sulcus and as the posterior border of the tumor. Invasion direction was toward the parietal lobe in 13 patients, the occipital lobe in 4 patients, the isthmus of the cingulate gyrus in 19 patients, the insula/basal ganglia in 3 patients, and the splenium of the corpus callosum in 8 patients. Although the isthmus of the cingulate gyrus and the occipital lobe are located just posterior to the posterior medial temporal lobe, there was a significantly greater preponderance of invasion toward the isthmus of the cingulate gyrus than toward the occipital lobe (p = 0.00030, McNemar test). Based on Schramm’s classification for the medial temporal tumors, 4 patients had type A and 20 patients had type D tumors. The parietooccipital fissure determined the posterior border of the tumors, resulting in a unique and identical radiological feature. Diffusion spectrum imaging (DSI) tractography indicated that the fibers running through the posterior medial temporal lobe toward the occipital lobe had to detour laterally around the bottom of the parietooccipital fissure. CONCLUSIONS Posterior medial temporal gliomas present identical invasion patterns, resulting in unique radiological features that are strongly affected by the parietooccipital fissure. The parietooccipital fissure is a key anatomical landmark for understanding the complex infiltrating architecture of posterior medial temporal gliomas.

The salivary glands

There are three paired major salivary glands of the head and neck, all named according to their location and each contributing to saliva and enzyme production via their respective ducts to assist with mastication and digestion. At rest, the lion’s share (60%) of saliva production is from the submandibular glands. On stimulation, the parotid contribution increases from 20% to 50%. There are up to 1000 minor salivary glands found within the submucosa of the oral cavity – 1-2mm in size and predominantly mucous in nature. The parotid glands are irregular shaped masses of lobulated tissue situated on the side of the face, reaching from the zygomatic arch superiorly to the upper part of the neck inferiorly where they overly the posterior belly of digastric and upper sternocleidomastoid muscle. Anteriorly, the gland lies between the posterior border of the mandibular ramus before continuing below the external acoustic meatus towards the mastoid process posteriorly.

Variances of the intraarticular landmarks for anterior cruciate ligament tibial footprint: Tibial eminencies have less variability than lateral meniscus on sagittal magnetic resonance scans

Objective: The purpose of this study was to analyze the sagittal plane variations of intraarticular landmarks for single bundle anterior cruciate ligament (ACL) reconstruction including lateral meniscus, medial and lateral tibial eminencies. Methods: T2 weighted sagittal magnetic resonance (MR) scans of 80 skeletally mature patients aged between 18 to 60 years and without any sign of ligament and meniscal injuries were viewed. Midpoint of ACL, most posterior aspect of anterior horn of lateral meniscus (LMAH), tip of medial eminence (ME) and lateral eminence (LE) were identified on widest antero-posterior (A-P) distance of tibial plateau according to of Staubli-Rausching method and variances were compared. Results: Mean location of center of tibial footprint of ACL at sagittal plane was found as 38.0±4.2% (range, 29-51%) on A-P distance of tibial plateau. Location of posterior border of LMAH, ME and LE were 38.0±12.4% (range, 21-62%), 52.3±4.2% (range, 41- 60%) and 59.5±4.4% (range, 51- 69%), respectively. Difference between the variances of ACL midpoint and LMAH was large enough to be statistically significant (p=<.001) with a large effect size (f=0.59), however differences between the variances of ACL midpoint and bony landmarks were not significant (ME, p=.65; LE, p=.33). Intra and interobserver agreement for measurement of all parameters were detected as moderate to good. Conclusion: There was no constant relationship between ACL midpoint and posterior border of LMAH on sagittal plane MR images. Difference of variances between ACL midpoint and ME and LE were significantly lower than of variances of LMAH.

GONIAL ANGLE DETERMINATION; A COMPARISON BETWEEN LATERAL CEPHALOGRAM AND BOTH HEMISPHERES OF ORTHOPANTOMOGRAM

Objective: To evaluate the mean values of Genial angle measured by Lateral cephalogram and Orthopantomogram. Study Design: comparative cross sectional study. Place and Duration of Study: Armed Forces Institute of Dentistry, Rawalpindi, from Aug 2018 to Feb 2019. Methodology: Patients irrespective of gender between the ages of 13-20 who reported for the treatment of class I malocclusion with complete anterior dentition were included. Orthopantomogram and lateral cephalogram were drawn by the same person. Gonial angle on orthopantomogram was measured by drawing tangents on posterior border of ramus and lower border of mandible on both halves of orthopantomogram. On lateral cephalogram the angle was measured between ramus and mandible. Gonial angle measured from lateral cephalogram and orthopantomogram were compared. T-test was applied. Results: Mean age of the individuals was 18.33 ± 3.97 years. The mean gonial angle measured on lateral cephalogram was 122.66 ± 1.64 degrees while the mean gonial angle measured on right and left side of orthopantomogram was 122.41 ± 1.56 degrees and 122.33 ± 1.55 degrees respectively. Conclusion: Orthopantomogram can also be used to measure gonial angle as accurately as a lateral cephalogram with the advantage that there are no superimpositions and both the gonial angles can be measured simultaneously on orthopantomogram.

A hemangioma in the masseter muscle: a case report

Intramuscular hemangiomas of the masseter muscle are uncommon tumors and therefore can be difficult to accurately diagnose preoperatively, due to the unfamiliar presentation and deep location in the lateral face. A case of intramuscular hemangioma of the masseter muscle in a 66-yearold woman is presented. Doppler ultrasonography showed a 34× 15 mm hypoechoic and hypervascular soft tissue mass in the left masseter muscle, suggesting hemangioma. The mass was excised via a lateral cervical incision near the posterior border of the mandibular ramus. The surgical wound healed well without complications.

Two new species of the hillstream loach genus Indoreonectes from the northern Western Ghats of India (Teleostei: Nemacheilidae)

The hill stream loach genus Indoreonectes is endemic to peninsular India south of the Satpura hill ranges and is represented by three species I. evezardi, I. keralensis and I. telanganaensis. Indoreonectes evezardi has been suggested as a species complex based on recent genetic studies; however, due to lack of type material the species delimitation has been difficult. Here we redescribe I. evezardi collected from its type locality and describe two new species from the northern Western Ghats of India. Indoreonectes neeleshi, described from Mula River tributary of Godavari river system, can be diagnosed from all its congeners based on a combination of characters: inner rostral barbel reaching middle of nostril; maxillary barbel reaching midway between eye and posterior border of operculum; dorsal hump behind nape; bars on lateral side of the body wider than inter-bar space; total vertebrae 35 and dorsal fin insertion between 13th and 14th abdominal vertebrae. Indoreonectes rajeevi, described from Hiranyakeshi River of the Krishna river system, differs from all its congeners based on a combination of characters: inner rostral barbel reaching anterior margin of eye; maxillary barbel reaching posterior border of operculum; conspicuous black markings on lower lip, dorsal hump absent; total vertebrae 36 and dorsal fin insertion between 12th and 13th abdominal vertebrae. Further, I. neeleshi differs from its congeners by the raw genetic distance of 6.8–14.4% for the cox1 gene and 5.7–16.2% for the cytb gene, while I. rajeevi differs from its congeners by the raw genetic distance of 10.9–14.0% for the cox1 gene and 11.8–15.8% for the cytb gene.