Lingual foramina on the mandibular midline revisited: a macroanatomical study

The purpose of the present study was to determine the incidence, size, location, course, and content of the foramina and bony canals located on the lingual side of the mandibular midline. Fifty dry human mandibles were morphometrically analyzed by measuring the distances of these midline foramina from the mandibular base and the dimensions of these foramina and their bony canals. In addition, macro- and microanatomical dissection was performed on 12 intact cadaver mandibles. The macroanatomic midline foramina were classified into superior and inferior genial spinal foramina according to their vertical location with respect to the genial spines. This study showed that out of 50 dry mandibles, 49 (98%) had at least one midline lingual foramen; only one lacked a true midline foramen. Evaluation of the microanatomical dissections indicated a clear neurovascular bundle in both superior and inferior genial spinal foramina and canals. For the superior canal, the content was found to derive from the lingual artery and the lingual nerve. For the inferior canal, however, the arterial origin was submental and/or sublingual, while the innervation derived from a branch of the mylohyoid nerve. In conclusion, different kinds of lingual foramina have been identified according to their location. The superior and inferior genial spinal foramina have different neurovascular contents, determined by their anatomical location above or below the genial spines.     

Accessory mental foramina and nerves: Application to periodontal,periapical, and implant surgery

Recent studies investigating accessory mental foramina using developments in diagnostic imaging have primarily defined the morphology of the foramina; however, few studies have described the structures passing through them. Additional clinical knowledge of the foramina is therefore required for preoperative diagnosis prior to surgery, including implant, periodontal and periapical surgery. In this study, we investigated the accessory mental foramina and the associated nerves and arteries in donated cadaveric mandibles using anatomical and radiological observation methods. We examined 63 mandibles with overlying soft tissue by cone‐beam computed tomography and noted the existence of the accessory mental foramina. Mandibles with accessory mental foramina were subsequently analyzed. Additionally, the neurovascular bundles passing through these foramina were dissected using anatomical methods.The incidence of accessory mental foramina was 14.3%. The larger foramina tended to be located anteriorly or superiorly and proximal to the mental foramen, while the smaller foramina tended to be located posterosuperiorly and distal to the mental foramen. The mental foramen ipsilateral to the accessory mental foramen was smaller than the one contralateral to it. The comparatively distant and large accessory mental foramen included an artery.This study elucidated the relationship between accessory mental foramina and the associated nerves and arteries. We believe that the results will contribute to the clinical dentistry field. Clin. Anat. 29:493–501, 2016. © 2015 Wiley Periodicals, Inc.     

Relationship between accessory foramina and tumour spread in the lateral mandibular surface

The spread of tumour cells to the mandible has been well recognised and invasion of the edentulous alveolar ridge by tumour through accessory foramina has been documented. Tumour infiltration can also occur through the lateral cortical plate, but the number and distribution of accessory foramina on this surface has not been reported. Lateral surfaces of 89 mandibles were examined and accessory foramina which showed a direct communication with the underlying cancellous bone were charted. It was found that the number of accessory foramina varied greatly from specimen to specimen. Only 70.8% of mandibles showed foramina in the coronoid, sigmoid and condylar sections; of these 93.7% exhibited foramina in the condylar section, 23.8% in the coronoid and only 19% in the sigmoid section. This finding confirms that the current practice of conserving part of the ascending ramus posterior to the coronoid process following surgery is sound. Similarly in the rest of the lateral surface, foramina were present in the upper third section in 97.8% of mandibles, 61.8% in the lower third and 58.4% in the middle third sections. This result justifies the principle of rim resection in appropriate cases and the recognition that the alveolar section is commonly invaded before the rest of the body. The number and distribution of foramina may be of greater significance following radiotherapy when the foramina could provide multiple direct channels for invasion of tumour cells from the lateral surface to the medulla.     

Variation in accessory mental foramen frequency and number in extant hominoids

Nerves providing sensation to the lower face and jaw exit the mandibular canal via the mental foramen. In humans, there are many documented occurrences of additional foramina (accessory mental foramina, AMFs) on the lateral mandibular surface that may also contain nervous structures. There are large discrepancies in the literature regarding how often AMFs occur in humans, and investigations of non-human hominoid AMFs are rare. Consequently, the causes of interspecific diversity in this variable have not been explored. This project seeks to compare the frequency and number of AMFs between males and females, and among human regional groups and hominoid subspecies and species, and to investigate possible causal factors for any differences identified. No significant differences were found between males and females in any group. Gorillas and orangutans had the highest percentages of individuals with AMFs and the highest mean number of foramina, while modern humans and siamangs had the lowest figures for these variables. Significant differences (p < .05) were found for the mean number of foramina between most pairs of species. The results also showed that species with mandibles that are larger overall, have a larger area anterior to mental foramen, and a longer mandibular canal typically present more AMFs. The strongest correlation was found between the mean number of mental foramina and mandibular canal length. We suggest that these results provide preliminary support for the hypothesis that increasing mandibular canal length increases the likelihood that that nerves will ramify, leading to greater frequencies of accessory mental foramina.     

Mandibular lingual canals distribute to the dental crypts in prenatal stage

Purpose

To describe configurations of human prenatal mandibular, lingual canals using a limited-field cone beam computed tomography (CBCT) to examine their origin and anatomical significance.

Materials and methods

Nine fetal mandibles were examined using a CBCT. Mandibular maturity was assessed according to the mandibular size measured directly and image findings on development of dental crypts. Mandibular, lingual canals and the related foramina (mandibular, mental, and lingual foramina) were observed on axial, sagittal, and cross-sectional images. The horizontal position of mental and lingual foramina was assessed by direct observation using a loupe.

Results

In all nine mandibles, CBCT images depicted three separate mandibular canals, which individually occurred at the ramus area. One was a short canal directly connecting to the permanent molar crypt. The other two showed a parallel course, following the mandibular corpus toward the frontal area; the upper one connected to the mental foramen, and the lower one distributed anterior area of canine and incisor crypts. Lingual foramina were observed bilaterally in eight of nine mandibles, whose horizontal position was lingual against the crypt of deciduous canine. The lingual canals occurred from lingual foramina, and connected to the close deciduous tooth crypt or the mandibular canal distributing in the frontal area.

Conclusions

It was suggested human dentition could be developed by plural mandibular and lingual canals.     

Anatomical classification of accessory foramina in human mandibles of adults, infants, and fetuses

In the past few decades, a number of studies have reported that accessory foramina are located on the internal aspect of the mandible, indicating their potential importance for effective and successful clinical procedures. The aim of this study is to evaluate adult, infantile, and fetal human mandibles for occurrence of accessory foramina. To our knowledge, this is the first time that an attempt has been made to examine their particular co-location using a systematic approach and perspective. A total of 397 human mandibles, including 299 adult, 18 infantile, and 80 fetal, were investigated macroscopically for the frequency, position, and diameter of accessory foramina. In 96 % of investigated adult mandibles, at least one accessory foramen was found. Foramina were located either superior or inferior to the genial tubercle, as well as lateral to the tubercle. Bearing in mind their usual location, four different types of coexistence of foramina were distinguished. Accessory foramina were also present in similar locations in infantile and fetal mandibles. Accessory mandibular foramina are constant structures of human mandible. Their frequency, size, and location vary depending on the type of the foramen. Observations on children and fetal mandibles showed no significant differences in evaluation of accessory foramina, with the exception of lower occurrence in this group of subjects.     

The relationship between accessory foramina and tumour spread on the medial mandibular surface

The medial cortical surface of the mandible can be involved by tumour infiltration from the floor of the mouth. A detailed study of spread via accessory foramina through the edentulous alveolar crest has been previously undertaken, but no similar study has been carried out for the medial surface. In order to gain further appreciation of the mode of tumour spread, a study of the number and distribution of accessory foramina on the medial mandibular surface was performed on 89 mandibles. The number of foramina varied greatly from specimen to specimen. In the ascending ramus above the inferior dental foramen, 3 mandibles showed no foramina; the condylar section possessed the greatest proportion followed by the sigmoid and the coronoid. On the rest of the medial surface below the inferior dental foramen, all specimens showed at least 1 accessory foramen; the greatest concentration was in the middle third along the path of the inferior dental canal, followed by the upper third and the lower third section. Accessory foramina were repeatedly present at certain dedicated sites. The medial facing wall of the inferior dental foramen was found to be the commonest dedicated site (98.3%) followed by foramina on either side of the genial tubercles (71.9%), the digastric fossa (71.9%) and the median foramen above the genial tubercles (64%). The findings of this study are in keeping with the current observation that the lower border is least commonly involved in tumour spread. In view of the presence of accessory foramina along the inferior dental canal and especially on the medial facing wall of the inferior dental foramen, it is imperative to preclude tumour spread in this region prior to undertaking the conservative rim resection procedure. Medial to the symphysis the alveolar mucosa dips down almost to the level of the dedicated foramina in the vicinity of the genial tubercles. As a general rule the attached muscle forms a barrier to tumour spread except in the later stages, however, in irradiated mandibles resistance to spread has been previously reported to be diminished. Under these circumstances, it is possible that the numerous accessory foramina reported in this study could facilitate a direct pathway into the cancellous bone.     

Radiological and Microsurgical Anatomy for Variation of the Mandible: Comparative Study of Human and Macaca fascicularis

Recent studies using cone‐beam computer tomography (CBCT) have added to our understanding of anatomical variation in the mandible of humans. However, the distribution of nerves cannot be revealed by CBCT. There have been investigations of the distribution of nerves relating to the mandible, but some proposed causes of these variations remain controversial. In this study, we observed a total of 10 sides from five mandibles of Macaca fascicularis of unknown age and sex using CBCT and dissection under stereomicroscopy. Nine of the 10 sides had two mental foramina in each side. Innervation by the mental nerves depended on the locations of those foramina. The long branch to the mandibular angle ran with a branch of the facial artery, which joined the mental artery in all 10 sides. Five specimens had a median perforating canal in the mandibular bone. In addition, a branch of the sublingual artery, which joined with the small branches of the submental artery, entered the mandibular bone from the median lingual foramen. This foramen was located in the lower part of the mandibular symphysis and passed via the median perforating canal to exit from the median labial foramen, also located in the lower part of the mandibular symphysis. We speculate that the median perforating canal of the mandible, rarely found in humans, is the remnant of the feeding artery of the fetal mandible, and in M. fascicularis is seen in all specimens because they have no mental protuberance. Anat Rec, 300:1464–1471, 2017. © 2017 Wiley Periodicals, Inc.     

An assessment on spiral CT scan of the superior and inferior genial spinal foramina and canals

To characterise the superior as well as the inferior genial spinal foramen and their bony canal using a large CT data sample. The study included 555 mandibular spirals CT scans, taken from patients for pre-operative implant planning. Basic observation by three observers included the number of canals, their respective anatomical location and morphological variations. Furthermore, linear measurements were performed to describe the foramina and canal characteristics. On spiral CT scans, the superior and inferior genial spinal foramina were detected in 448 CT scans (81%). In 29% of the mandibular CTs, two or more midline canals were noted. 47% of the foramina were located in a position inferior to the genial spines; the others were located in a superior position. The mean (SD) lingual and buccal diameters of the canal structures were 0.73 (0.27) and 0.54 (0.29) mm, respectively with an average length of 3.94 (1.29) mm. The canal was located on average 7.40 (5.31) mm from the mandibular base at the lingual entrance and 7.96 (3.47) mm at the buccal canal end point. The average canal extended towards the buccal bone for an average 37% of the bone width. The results demonstrated the presence of both superior and inferior genial spinal foramina, with 29% of the individuals having double foramina. About 53% of the foramina was located superior to the genial spines. Considering its neurovascular content, these foramina should be carefully evaluated during pre-operative planning.     

Ligaments of the lumbar neural foramina: A sectional anatomic study

The ligaments of the lumbar neural foramina have not been systematically described. We sectioned the lumbar spines of 15 cadavers in the sagittal plane with a cryomicrotome and identified the ligaments in the neural foramina. Fibrous ligaments were identified in every lumbar neural foramen. The most constant ligament was a band of fibrous tissue behind the anulus fibrosus and distinct from it, originating in one vertebral body and inserting in the next. Ligaments connecting the posterior disc margin and the superior articular process were found in 48% of the neural foramina. A band of fibrous tissue originating from the anulus fibrosus and inserting along the pedicle and superior articular process was found in 44% of the foramina. Three other distinct types of ligament were found less commonly. Ligaments, which some investigators believe may contribute to lateral spinal stenosis, are commonly present in the neural foramina.     

Prevalence of Accessory Mental Foramina: A Study of 4,000 CBCT Scans

The presence of accessory mental foramina (AMF) is an important consideration prior to any dental implant and surgical treatment to avoid injury to the neurovascular bundle and subsequent postoperative complications. The aim of this retrospective study was to determine the prevalence of AMF from a substantially large sample of the Australian population. The cone beam computed tomography (CBCT) scans of 4,000 patients showing the mandible were examined. All mental foramen (MF) were visualized and no cases were excluded. The number of MF/AMF, sex, and age were recorded. The prevalence of AMF was found to be 6.4% (254 patients) in this study. Twelve patients exhibited bilateral AMF, and 11 had three mental foramina on one side. One case had a total of five mental foramina with three on the right and two on the left side. No significant sex preference was discovered. This is the largest study ever to be conducted to evaluate the prevalence of AMF. With nearly one in 15 individuals found to have AMF, clinicians must be acutely aware of this anatomical variation and treatment plan for each case accordingly. Clin. Anat. 32:1048–1052, 2019. © 2019 Wiley Periodicals, Inc.     

Familial interstitial deletion 11(p11.12p12) associated with parietal foramina,brachymicrocephaly, and mental retardation

Parietal foramina may be an isolated autosomal dominant trait or found in syndromes. We report on two related individuals who have multiple anomalies with parietal formaina and the deletion of 11(p11.12p12) due to the inheritance of a derivative chromosome 11 from an insertional translocation dir ins(13;11)(q14.1;p11.12p12). Results of initial chromosome analyses on the proposita and her maternal halfuncle were reported as normal. However, the clinical manifestations and family history suggested a chromosomal cause and cytogenetic studies were performed on the proposita's mother. A derivative chromosome 13 was initially identified and further evaluation documented a derivative 11 as the reciprocal product. This family illustrates the importance of performing chromosome studies on the normal intervening relatives in families with multiple affected individuals with mental retardation and minor anomalies as one of the two reciprocal products may be more easily detectable in a balanced carrier. Additionally, the finding of del(11)(p11.12p12) may provide a map location for a syndrome which includes parietal foramina. © 1993 Wiley-Liss, Inc.     

Incidence and morphological study of zygomaticofacial and zygomatico-orbital foramina in dry adult human skulls: the non-metrical variants

Morphological diversity in the form of multiple zygomaticofacial (ZF) foramina was studied in 165 dry, unsexed adult human skulls. Zygomatic bones revealed variation in the number of foramina on their orbital and facial aspects. These were absent in 72 (21.8%) sides. A single ZF foramen was seen in 148 (44.9%) sides. Two ZF foramina were found in 92 (27.9%) sides, out of which 29 (8.8%) sides had one zygomatico-orbital (ZO) foramen, while 63 (19.1%) sides had two ZO foramina. Three ZF foramina, a relatively uncommon occurrence, were found in 17 (5.1%) sides, which included eight (2.4%) sides with one less and nine (2.7%) sides with the same number of ZO foramina. Four ZF foramina were seen in one (0.3%) side with three on the orbital aspect, a feature not reported before. The zygomatic nerve may be disrupted on elevating periorbita from the lateral wall during orbital surgery, and care should be taken to prevent injury to the nerve during the lateral orbitotomy approach to access intraorbital soft tissue tumors.     

Position of the mental foramen in a northern regional Jordanian population

BACKGROUND: The mental foramen is frequently encountered in a number of maxillofacial surgical procedures. Its position has been shown to vary according to race. The aim was to study the position, shape, and appearance of the mental foramen, as seen on panoramic radiographs of Jordanians, and to compare our findings with international values. PATIENTS AND METHODS: Panoramic radiographs were randomly selected from the records of dental patients attending three dental services, and were analyzed according to patients' age and gender, and the mental foramina's anterior-posterior and superior-inferior positions, shape, appearance, and symmetry. RESULTS: There were 860 cases (1,720 sides) with a female-to-male ratio of 1:1.4, and mean age of 24. The most frequent anterior-posterior position was in the area between the long axes of first and second mandibular premolar teeth. With advancing age, there was an increase in the frequency of more posterior positioning. The anterior-posterior position was asymmetrical in 33% of cases. The most frequent superior-inferior position was below the level of apices of mandibular premolar teeth roots. With advancing age there was an increase in the frequency of more inferior positioning. The superior-inferior position was asymmetrical in 14% of cases. The majority of foramina were round in shape, and the most frequent appearance was the continuous type. Accessory mental foramina were seen in 10% of the cases. CONCLUSION: The position of the mental foramen on panoramic radiographs in this selected group of Jordanians is most commonly below and between the mandibular premolar teeth, and the most frequent appearance was the continuous type. These results are similar to previous findings in Caucasian populations.     

Localization of the supraorbital,infraorbital, and mental foramina using palpable,bony landmarks

The purpose of this study was to locate the infraorbital, supraorbital, and mental foramina by using palpable anatomical landmarks that are conducive to surgical use. Fourteen embalmed cadavers (27 sides) were dissected to expose the supraorbital, infraorbital, and mental foramina. Measurements were made from the lateral orbital rim at the zygomaticofrontal (ZF) suture to both the supraorbital and infraorbital foramina. The distance from the inferior orbital rim at the zygomaticomaxillary (ZM) suture to both foramina was also measured. The distance to the mental foramen was measured from the angle and the inferior border of the mandible. The supraorbital foramen was located 26.2 ± 2.8 mm medial and 13.5 ± 3.7 mm superior to the ZF suture. The infraorbital foramen was located 23.8 ± 3.1 mm medial and 30.9 ± 3.8 mm inferior to the ZF suture, on average. Vertical measurements made from the ZM suture to the supraorbital foramen averaged 34.4 ± 3.6 mm and from the ZM suture to the infraorbital foramina averaged 7.6 ± 2.2 mm. The mental foramen was 64.2 ± 6.4 mm medial to the angle of the mandible and 12.9 ± 1.6 mm superior to the inferior border of the mandible. This study provides data that may be useful in predicting the location of the supraorbital, infraorbital, and mental foramina using palpable landmarks. These data may be particularly helpful for surgery in patients with missing teeth or fractures of the maxillary bone. Clin. Anat., 2010. © 2009 Wiley‐Liss, Inc.     

The clinical anatomy of accessory mental nerves and foramina

Since three‐dimensional computed tomography was developed, many researchers have described accessory mental foramina. The anatomical and radiological findings have been discussed, but details of accessory mental nerves (AMNs) have only been researched in a small number of anatomical and clinical cases. For this article, we reviewed the literature relating to accessory mental foramina (AMFs) and nerves to clarify aspects important for clinical situations. The review showed that the distribution pattern of the AMN can differ according to the position of the accessory mental foramen, and the reported incidence of AMFs differs among observation methods. A review of clinical cases also revealed that injury to large AMF can result in paresthesia. This investigation did not reveal all aspects of AMNs and AMFs, but will be useful for diagnosis and treatment by many dentists and oral and maxillofacial surgeons. Clin. Anat. 28:848–856, 2015. © 2015 Wiley Periodicals, Inc.     

High seroprevalence of Helicobacter pylori infection in non-institutionalised children with mental retardation

Eighty-four children with mental retardation (34 boys, 50 girls; age range 2-18 years, median 6 years) and 84 age- and gender-matched outpatient controls were studied. All children were living at home, had never stayed in an institution, and came from the same urban area. Seropositivity for Helicobacter pylori was found in 42 (50%) of 84 mentally retarded children and 16 (19%) of 84 controls (p < 0.01). Socio-economic factors did not differ between the two groups. The findings indicated that a higher prevalence of H. pylori infection occurs in children with mental retardation, regardless of whether they are institutionalised.     

Localization of important facial foramina encountered in maxillo-facial surgery

Knowledge of the location of foramina in the maxillo-facial region is necessary in clinical situations requiring regional nerve blocks and in open as well as endoscopic surgical procedures to avoid injury to corresponding nerves. In this study, measurements were taken on 79 adult dried human skulls to determine the position of the supraorbital, infraorbital, and mental foramina. Supraorbital foramina were found to be approximately 25 mm lateral to the midline, 30 mm medial to the temporal crest of the frontal bone, and 2-3 mm superior to the supraorbital rim. Additional exits for branches of the supraorbital nerve were present in 14% of skulls. The intersection of the zygomatico-maxillary suture with the inferior orbital rim was a readily palpable landmark for locating the infraorbital foramen. This foramen was approximately 7 mm inferior to the inferior orbital rim and 28.5-mm lateral to the midline. Mental foramina were on average, 25.8-mm lateral to the midline and about 13-mm superior to the inferior mandibular margin. Both the infraorbital and mental foramina were most often on a vertical line with the second premolar (Position 3). The distances of the foramina from the midline were similar on both sides demonstrating facial symmetry. In about 80% of skulls, the supraorbital, infraorbital, and mental foramina/notches were along the same vertical line. These measurements may be of value to clinicians in localizing and safeguarding these nerves and providing effective nerve blocks.     

The arrangement of the trabecular bone in the vestibular surface of the human fetus mandible. A scanning electron microscopy study

The characteristics of trabecular bone in human fetuses at seven to nine months of intra-uterine life were studied in the vestibular surface of the mental and body portions of the mandible. In the mental portion, many circular trabeculae joined by "bridges" were observed in the alveolar region (AR). In the 8-month old fetus are trabeculae with tortuous disposition in the medium region (MR). Oblique trabeculae with superior and inferior dispositions defining a triangular area (future mental fossae) are verified in 9-month old fetuses. Trabeculae circularly disposed and vascular foramina are present close to the apex of this area. In the basilar region (BR) some trabeculae obliquely oriented are observed disposed near to the mandibular symphysis. The longitudinal bundles of collagen fibers assume an antero-posterior direction. At 9-month age the vascular foramina range from 6 to 20 microns and the osteocyte lacunae ranging from 1 to 4 microns diameter, are present in mandibles from all ages examined. In the body portion the presence of circular trabeculae joined by "bridges" is the main characteristic of the AR. In the MR most of the trabeculae are circular and the longitudinal trabeculae of this region assume an antero-posterior direction. The laminar, antero-posterior and juxtaposed trabeculae lying parallel to mandible base are a characteristic of the BR. The bundles of collagen fibers exhibit the same pattern of the trabeculae. The vascular foramina of the BR are smaller than that of the precedent regions. In the body portion of the mandible from all ages examined the osteocyte lacunae range from 1 to 4 microns in diameter.     

The extramandibular inferior alveolar nerve in cases with severely atrophic lower jaws

There are very few evidences on the extramandibular course (EMC) of the inferior alveolar nerve (IAN). We report here two such cases. The first one was encountered at dissection, in a human adult female cadaver where the right IAN terminal division was identified in the premolar region, above a severely atrophied mandibular body. The second case was a patient evaluated by cone-beam CT, who presented with an extremely atrophic mandible with bilateral extramandibular courses of the IANs. Such severe atrophy of the mandible may be considered as residual ridge class 7 along with the existing Atwood classes. EMCs of the IAN may not only occur in extreme mandibular atrophy, but also in dentate mandibles. In edentulous mandibles, an extramandibular IAN may complicate local surgical procedures or hamper denture wearing.